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Scott Hazen Mueller
Aug 26, 2005, 8:23:04 PM8/26/05
to
area forecast discussion
fxus66 kmtr 270016 cca
afdmtr
area forecast discussion
national weather service san francisco ca
500 pm pdt fri aug 26 2005
.discussion...stratus off the central california coast is eroding
rapidly this afternoon under the influence of a strengthening
northerly gradient and a compressed marine layer brought about by
the ridge moving in from the southeast. however clearing along the
coast may be short lived if a well developed eddie off the coast near
bodega bay act to once again push the stratus to the coast this
evening. if the stratus makes it back to the coast this evening the
shallow marine layer (approx. 1000 ft per the fort ord profiler) and
the nearly 3 mb northerly gradient from acv to sfo will inhibit
stratus from moving into sfo bay and the santa clara valley.
as anticipated many locations across the region are seeing warmer
temperatures this afternoon. temperatures are anywhere from 1 to 5
degrees warmer compared to yesterday at this time with livermore
coming in 9 degrees warmer at this hour. models maintain a slight
warming trend into the weekend raising 850 mb temps to around 24 c
(inland) by saturday. 500 mb heights will also increase to nearly 592
dm over the weekend. this is all in response to high pressure nudging
into our area from the southeast.
on sunday a strong upper low over the gulf of alaska will dig
southeastward breaking down the ridge aloft and weakening the high
over the eastern pacific. this will introduce cooler air over
the region. latest model timing has the trof axis moving through the
state monday and tuesday and lifting to the northeast late tuesday.
temperatures will then gradually begin to warm as high pressure
strengthens over the eastern pacific and great basin.
&&
corrected discussion
.aviation...vfr is expected at area airports through the evening...
including kmry and ksns which usually see stratus & fog rolling back
in at or just after sunset during the summer. an upper high centered
over socal was strengthening this afternoon with a ridge extending
northward over northern ca. the marine layer has compressed due to
large scale subsidence associated with the upper high. marine
inversions are now based near 900 feet per ft ord profiler data.
another factor in the mix tonight is the large eddie located about
100 miles west of san francisco. kmry will sometimes go light
offshore winds later in the evening under this large scale weather
situation...and the thought is that as the eddie moves by it may also
help hold a localized light easterly component to the sfc wind here
at kmry...thus holding off stratus or fog til well after midnight.
ksts...koak...kmry and ksns may have a few hours of lifr/vlifr early
sat am...but burn-off will be fairly quick. vfr is forecast at ksfo
and ksjc. all this falls in line with the latest nam model forecast
showing boundary layer humidity staying mostly over the waters
tonight. one note about ksfo winds for this eve...half moon bay buoy-
ksfo gradient is about 1.6 mb which is a fairly strong...but gusty
winds at angel island (such is the case this eve) often minimizes
wind strength at ksfo. another signature of how localized it is...
ksfo-ksac is only 1.7 mb thus ksfo winds should diminish after
sunset.
&&
.mtr watches/warnings/advisories
tngt...sca...sfo bay.
&&
__________________________________________________________________________
public forecast: horne
marine/aviation: canepa
noaa`s nws on the web at weather.gov/sanfrancisco
Boycott Internet Spam: See <URL:http://spam.abuse.net/spam/>
The National Weather Service data is made available courtesy of the National
Science Foundation-funded UNIDATA Project and the University of Michigan.
Scott Hazen Mueller
Aug 27, 2005, 2:23:16 AM8/27/05
to
area forecast discussion
fxus66 kmtr 270528
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...the 500 mb ridge over the desert sw built wwd tda as
forecast...and max temps rose several degrees over most of the
districts interior. the coast did not share in the warming as a
westerly flow continues aloft. the marine layer is rather shallow...
about 1200 feet at ft ord. 6 pm pressure gradients showed a
strengthening low level nly flow. acv-sfo was 3.4 mb...compared to
3.1 at that time yda. pt arena-pt piedras blancas was 1.6 n-s...vs.
only 0.5 yda. for most of the day the sfo-sac gradient was weaker
than yda but by 6 pm it was up to 2.2 mb compared to 1.3 yda.
there is a well defined eddy off the san mateo coast...moving s
parallel to the shore. earlier tda stratus cleared from the coast
except from pt reyes n but now its moved back onshore at pillar pt
and expect the clouds to shroud most of the littoral by mrng. the
proximity of the eddy could be why the sfo-sac gradient increased
fairly rapidly late this aftn. with the shallow marine layer...dont
expect the low clouds to go far inland...maybe to oakland and into
the nrn salinas valley. the eta boundary layer rh pattern conforms
fairly well to this thinking.
sat should be the warmest day overall across the region with max
temps rising a few degrees inland due to a warmer airmass aloft and
continuing weak onshore flow. it will still be warm inland on sun
but the models begin lowering 500 mb heights slightly as an upper
trof approaches the pacific nw from the gulf of ak. temps in the
coastal valleys should be a few degrees cooler that day with a
stronger...earlier seabreeze than on sat.
on mon expect significant cooling over the interior as the gulf of
ak trof moves into nrn ca with stronger onshore flow and cooler air
aloft. after the trof moves thru...surface high pressure will build
into the great basin on tue setting up a weak to moderate offshore
flow over our district...almost right on schedule as august ends and
the sep/oct sunny season begins on the coast. tue should be
virtually fog free and much more isothermal across the district than
tda/sat...warmer on the coast and cooler inland than currently. the
dgex then hints at a southerly surge sometime on wed but timing is
still an issue.
&&
.aviation...vfr conditions continue at area airports this evening.
an upper high over socal will strengthen into sat basically keeping
the marine layer compressed due to large scale subsidence associated
with the upper high. ksts...koak...kmry and ksns may have a few hours
of lifr/vlifr early sat am. vfr is forecast at ksfo and ksjc.
&&
.mtr watches/warnings/advisories
tngt...sca...sfo bay.
&&
__________________________________________________________________________
Scott Hazen Mueller
Aug 27, 2005, 8:23:15 AM8/27/05
to
area forecast discussion
fxus66 kmtr 271136
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...the upper level ridge over the southwest will continue
to dominate the weather across the region today. koak 850mb temps
rose to 22c by yesterday afternoon and another degree or two of
warming is expected today...as a result interior locations will see
additional warming today as well. coastal areas will remain
seasonably cool as onshore gradients are a little stronger this
morning than last (2.1mb sfo-sac vs 1.2mb yesterday). stratus has
filled in along the entire central ca coast this morning but has only
worked into the north bay and nrn salinas valley...mainly due to the
relatively shallow marine layer (currently 1200 ft per the ft ord
profiler).
an upper low in the gulf of alaska will continue to dig southward
today and tomorrow and will begin to influence our weather on
sunday bringing increased onshore flow at the surface. inland areas
will experience cooling...however interior sections protected from
the seabreeze will see another hot day as 850 mb temps continue to be
in the 23-25c range and the marine layer remain shallow...about 1000-
1500ft. the upper trof axis will be across the pac nw and nrn ca on
monday and all areas will see significant cooling as temps aloft
cool and onshore flow is strong.
as the upper trof moves off to the east on tuesday surface high
pressure will build into the pacific nw and the great basin. offshore
wmc-sfo gradients begin to increase monday night and the gfs has a
maximum offshore gradient of about 12mb by 12z wednesday.
temperatures across the district will be nearly isothermal with
warm...fog free conditions near the coast but the main concerns
will be with fire weather as northeast winds increase across the
ridges and overnight rh recoveries will be poor.
&&
.aviation...widespread stratus has moved into the north bay this
morning and expect sts to have low visibilities through 17z.
stratus slowly moving into the sfo bay area through the highway 17
corridor and some clouds could move over the approach zone...but
with the shallow marine layer these clouds will burn off by
16-1630z.
&&
.mtr watches/warnings/advisories
tda...sca...sfo bay.
&&
__________________________________________________________________________
public forecast: kennedy
marine/aviation: w pi
Scott Hazen Mueller
Aug 27, 2005, 2:23:18 PM8/27/05
to
area forecast discussion
fxus66 kmtr 271602
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...shallow marine layer this morning...about 800-1000 ft
deep per the morning ft ord profiler. satl imagery indc that the
stratus is into the northern salinas valley...but that is basically
it.
ridging develops over the district today ahead of a deep trough in
the gulf of alaska centered near 140w. ridging continues into
sunday with hot temps inland...and cool along the coast. in fact...
h85 temps increase to 28c in southern monterey county on sunday.
current forecast looks good...no updates.
&&
.aviation...satellite imagery shows that stratus is already clearing
out of the bay area with sfo...oak and sjc already enjoying vfr
conditions. low clouds and fog remain over a large portion of the
north bay with santa rosa airport still reporting some light fog and
cigs of 100 feet. a break-out time of around 17z still looks
reasonable for that airport. with a 1000 foot marine layer...mry and
sns are still lifr but satellite imagery shows both airports right on
the edge of the clouds. thus...vfr by 17z looks good for those
airports as well.
&&
.mtr watches/warnings/advisories
tda...sca...sfo bay.
&&
__________________________________________________________________________
marine/aviation: anderson
Scott Hazen Mueller
Aug 27, 2005, 8:23:22 PM8/27/05
to
area forecast discussion
fxus66 kmtr 272126
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...as of noon the marine layer per the ft ord profiler
was between 800-1000 ft...no change from earlier. vis imagery indc
clear skies across most of the district...with sfc obs also
reporting clear skies. water vapor imagery indc a ridge continuing
to build over the west coast as a sharp trough crosses 140w in the
gulf of alaska.
the pattern will be progressive with a strong jet along the
us/canadian border as the calendar moves to september...normal for
this time of year.
sunday...hot day inland as h85 temps peak at 28c in southeast
monterey county as the upper trough passes 130w. the coast should
remain pleasant with the aftn seabreeze.
sunday night/monday...the sharp trough will move into the pacific
northwest sunday night and monday. this will lower the heights and
bring some cooling...especially inland as h85 temps cool. winds will
be gusty...especially along the coast and in the hills as the
gradient increases.
monday night through wednesday...weak ridging over the west as the
trough moves into the northern intermountain west. surface high noses
into the pacific nw bringing n to ne winds...especially over the
hills. however...does not look like a strong offshore wind event
since the mid level and upper level flow will be on-shore. temps
will be more isothermal with the surface flow n to ne...additionally
there will be little if any low clouds over the district.
wednesday night through saturday...a broad trough will develop over
the west coast. this will bring lowering heights and a return to
onshore flow...with cooler temps inland. the gfs even hints at a
southerly surface flow thursday into friday morning. this could cool
the inland valleys even more than the current forecast...especially
the santa rosa area.
&&
.previous aviation...satellite imagery shows that stratus is already
clearing out of the bay area with sfo...oak and sjc already enjoying
vfr conditions. low clouds and fog remain over a large portion of the
north bay with santa rosa airport still reporting some light fog and
cigs of 100 feet. a break-out time of around 17z still looks
reasonable for that airport. with a 1000 foot marine layer...mry and
sns are still lifr but satellite imagery shows both airports right on
the edge of the clouds. thus...vfr by 17z looks good for those
airports as well.
&&
.mtr watches/warnings/advisories
Scott Hazen Mueller
Aug 28, 2005, 2:23:09 AM8/28/05
to
area forecast discussion
fxus66 kmtr 280558
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...max temps warmed across most of the district tda as
the 500 mb ridge of hi pressure strengthened over the region. maxes
were up a good 4-8 degrees in most areas except on the coast and in
mry county where increases were smaller. bradley...in srn monterey
county...led the way at 108...but that was only 3 degrees warmer than
yda. the marine layer is only about 1000 feet deep.
7 pm pressure gradients included 4.1 mb acv-sfo (3.2 yda)...1.8
offshore wmc-sfo (0.3)...2.3 onshore sfo-sac (2.2) and 0.8 n-s pt
arena-piedras blancas (1.4).
the long advertised upper trof is edging sewd thru the ern pacific.
the water vapor pix show two shortwaves moving thru the base of the
trof...one shearing newd near 45/130 and a trailing feature
approaching 45/140 and dropping toward the se. the models indicate
that although there will be no cooling aloft over our district on
sun...by mid/late aftn the onshore flow will increase as the winds
aloft shift from anticyclonic to cyclonic. this should result in
some cooling in the coastal valleys but it will be hot again over the
interior.
the trof remains on schedule to move thru nrn ca on mon. it wont be
deep enough to bring a chance of rain but will send temps down over
inland areas with both significant cooling aloft and a stronger
onshore flow. with 850 mb temps forecast around 18 deg c on mon the
marine layer will not be completely washed out...but it will become
less well defined and deeper. expect a clear...cool...blustery day
all along the coast on mon.
by tue the models remain consistent in developing a weak to moderate
offshore flow over the district. the air aloft will still be cooler
than it is tda but with only a late aftn seabreeze...areas near the
ocean should warm up considerably. tue will be a much more
isothermal day than tda. tda max temps in the bay area varied
from around 60 coastside to the upper 90s well inland but on tue
the rangs should be only from the upper 60s to upper 80s...with
most cities in the district in the 80s. there will be little or no
fog/stratus tue and wed mrngs but by wed aftn the models indicate a
good chance of a southerly surge developing...which would return
stratus up the coast that day and into wed night.
after that the basic pattern will be a cool one with a medium
strength upper trof over the district...which will generate a strong
onshore flow and a deep marine layer thu thru sat with temps
dropping below normal.
&&
.aviation...ft ord profiler shows little change in marine inversion
depth since the afternoon. inversion bases are holding at about 800
feet. the stratus and fog has filled in fairly quick along the coast
and in monterey bay since the afternoon. the marine layer is
compressed under an upper level high so will continue to forecast
lifr cigs/vsbys moving into kmry and ksns. with the current depth of
the marine layer...am not expecting any appreciable amount of stratus
or fog reaching over to ksfo...ksjc or koak. the models have been
forecasting an increasing acv-sfo gradient sun eve into mon...showing
upwards of 8 mb mon aftn/eve.
&&
.mtr watches/warnings/advisories
tngt...sca...sfo bay.
&&
__________________________________________________________________________
marine/aviation: canepa
Scott Hazen Mueller
Aug 28, 2005, 8:23:10 AM8/28/05
to
area forecast discussion
fxus66 kmtr 281209 aaa
afdmtr
area forecast discussion...updated
national weather service san francisco ca
updated aviation discussion
.discussion...marine layer this morning has deepened slightly to a
little over 1000 feet per the ft ord profiler at 230 am. both the
fog satl imagery and sfc obs indc that the low clouds/fog has moved
into santa rosa and the northern salinas valley. water vapor imagery
indc that the trof in the gulf of alaska is near 135w...with one
vort max shearing ne into british columbia and another vort digging
to 45/140.
today and monday...trof moves into the pacific northwest. with h85
temps centered around 24c inland areas will be hot again today. as
the trof moves into the pacific northwest the onshore flow deepens.
deeper onshore flow and lower h85 temps will bring significant
cooling to most inland areas...except southern monterey county where
inland temps will top 100 degrees.
monday night through tuesday night...surface high builds into the
pacific nw as the trof moves into the rockies. this will bring a
weak to moderate offshore flow...however the mid and upper levels
remain onshore and weakly cyclonic so there is little support for a
significant wind event. temps will be more isothermal on tuesday.
wednesday...baggy trof will remain over the west coast. the eta12 is
indc that a southerly surge will develop which would bring stratus
to the coast...and cooling along the coast and in coastal valleys.
thursday through saturday...broad trof over the west with cyclonic
flow. this will bring a deep onshore flow with cooler temps.
&&
.aviation...the stratus has moved locally inland overnight and
brought vlifr ceilings to ksts and lifr ceilings to kmry and ksns
overnight. in the sfo bay...the stratus has moved through the golden
gate to the berkeley hills. onshore gradients have changed little vs
24 hrs ago but the marine layer has deepened a little...to 1300ft
per the ft ord profiler...even though the 850mb temps remain at or
a little warmer than yesterday. don`t expect the stratus to affect
the sfo approach again this morning even with the slightly deeper
marine layer and the stratus extending a little farther into the sfo
bay. ksts...kmry and ksns will see clearing mid to late morning
again today. the afternoon seabreeze will be a little stronger this
afternoon as onshore gradients increase in response to an upper
trough approaching from the northwest.
&&
.mtr watches/warnings/advisories
tdy...sca...pt arena to pigeon pt and sfo bay.
&&
__________________________________________________________________________
public forecast: strobin
marine/aviation: kennedy
Scott Hazen Mueller
Aug 28, 2005, 2:23:10 PM8/28/05
to
area forecast discussion
fxus66 kmtr 281742
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...visible satellite imagery shows stratus right against
the coastline...into the north bay valleys as well as the monterey
bay and salinas valley...but only locally into the san francisco
bay. however...low clouds that are over inland areas are already
showing signs of thinning so most places...except along the immediate
coast...should enjoy sunshine earlier today than yesterday. the
marine layer is still about 1100 feet deep per the fort ord profiler
data. bay area web cams show areas of fog as well as hazy sunshine in
spots. temperatures today are expected to be a little warmer than
yesterday overall with inland areas warming into the 90s to even
around 110 in the far interior portions of southern monterey county.
60s and 70s are expected along the coast.
an upper level trough is progged to move over the west beginning
tomorrow. this should cool temps a few degrees but it is expected
to remain rather warm well inland. by monday night surface pressure
gradients are progged to tighten from north to south with strong
winds expected over the coastal waters as well as gusty winds inland
funneling down the central valley. by tuesday morning...a brief
offshore flow pattern is indicated at the surface with breezy
northeast winds over the north and east bay hills. there still
doesn`t appear to be any upper support for a strong offshore event as
the 12z nam keeps the flow aloft more west to northwest. thus...an
afternoon seabreeze is still expected by tuesday afternoon...and the
westerly flow is forecast even at the surface by wednesday morning as
the upper trough continues to dig over california.
&&
.aviation...a shallow marine layer around 1000 ft and a weaker
onshore flow prevented stratus from forming ceilings at san francisco
bay area terminals ksfo...koak...and ksjc. low clouds did not
impact monterey bay area terminals kmry and ksns and north bay
terminal ksts until after midnight. dissipation was quick...and by
17z all these terminals were under clear skies.
with the upper level trough approaching the pacific northwest...the
marine layer will deepen today and tonight. this will allow the
stratus to move onshore earlier and penetrate farther inland.
ceilings will return to monterey bay area terminals as early as 04z
and san francisco bay area terminals after 10z. along with increasing
the stratus coverage tonight...the upper trough will also strengthen
the onshore gradient...leading to stronger afternoon winds at ksfo
gusting up to about 28 kt.
&&
.mtr watches/warnings/advisories
tda...sca...sfo bay.
&&
__________________________________________________________________________
public forecast: anderson
marine/aviation: sellers
Scott Hazen Mueller
Aug 28, 2005, 8:23:51 PM8/28/05
to
area forecast discussion
fxus66 kmtr 290008
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...satellite imagery shows that skies have cleared
completely over the district with afternoon temperatures are
running a few degrees warmer than yesterday at this time at many
spots. right now temperatures are ranging from the 60s and 70s near
the coast to the 70s and 80s around the bay area with 90s well
inland with temps in the warmest spots of interior monterey and
san benito counties from 101 to around 107.
high pressure over the state will weaken tomorrow as an upper level
trough moves over the west. this should cool temps a few degrees but
it is expected to remain warm well inland with highs continuing into
the 90s. by monday night surface pressure gradients are progged to
tighten from north to south with strong winds expected over the
coastal waters as well as gusty winds inland funneling down the
central valley. by tuesday morning...a brief offshore flow pattern is
indicated at the surface with breezy northeast winds over the north
support for a strong offshore event as the latest run of the nam
keeps the flow aloft more west to northwest. thus...an afternoon
seabreeze is still expected by tuesday afternoon...and the westerly
flow is forecast even at the surface by wednesday morning as the
increase in coastal stratus from the south on wednesday...and the
onshore surface flow is expected to persist through the remainder of
the forecast period in a weak upper-level trough pattern.
&&
.aviation...the models seem to have a great handle on the mdt-stg
and mainly dry (at least the southern portion of it) upper low moving
toward the pac nw. an upper level high remains over socal with a
ridge extending northward along the ca coast over our area. the upper
trough to our north is beginning to break down the ridge over us...
but this will happen at a quicker pace later tngt. for at least part
of tonight this leaves us with a continued shallow marine layer...
bases near 800 feet...and lifr conds moving into kmry and ksns in the
eve. the n-s gradient acv-sfo is strengthening like the models have
been forecasting. most of tonight will likely be vfr at ksfo...koak
and ksjc with the best chance of stratus nudging eastward over these
airports temporarily late tngt as the upper trough passes by to our
north. however given the southern extent of the upper low is mainly
dry this often ends up mixing out the marine layer entirely. so will
go ahead and cut back the duration of cigs in the 00z tafs as the
chances seem fairly good that there will only be a couple hours or so
of cigs in the bay area late tngt. angel island once again has gusty
west winds this aftn...but on occasion as the n-s gradient gets
stronger this can abruptly shift the stronger winds s to ksfo. right
now this is not the case...but this often becomes an hour by hour
situation that can only be caught by monitoring hourly metar obs. a
healthy gradient from half moon bay-ksfo exists...currently near 2
mb. plus the inversion depth is somewhat favorable in case the
strongest onshore winds decide to shift to ksfo later this eve. for
now current forecast near 30 kts looks good for ksfo.
&&
.mtr watches/warnings/advisories
tngt...sca...point arena to pigeon point...and sfo bay.
&&
__________________________________________________________________________
public forecast: anderson
Scott Hazen Mueller
Aug 29, 2005, 2:23:18 AM8/29/05
to
area forecast discussion
fxus66 kmtr 290545
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...max temps were about the same tda as yda over the
district as a warm airmass continued...but a well defined upper trof
is approaching from the nw and will bring cold advection and
stronger onshore flow on mon. coastal stratus is extensive and will
move a short distance inland tngt...but the cool trof and
strengthening nw winds should sweep the stratus away by mon aftn
resulting in a crisp...blustery day on the coast with significant
cooling inland due to the combination of the increased onshore flow
and cooler air aloft. coastal temps should not change much as
increased sunshine will counteract any airmass cooling. 7 pm
gradients showed the increasing onshore flow. sfo-sac was 3.2 mb...
up from only 2.1 two hours earlier and also from the 2.3 mb at 7 pm
yda. sfo-wmc had reversed to 1.1 onshore...it was 1.8 offshore
yda. the n-s gradient is also increasing. acv-sfo was 5.2 mb which
should keep stratus out of sfo tngt.
as the upper trof moves inland mon night/tue the low level flow will
shift from nwly to nly and a weak to moderate offshore flow will
develop from the great basin to the coast. its not expected to be
strong...the 500 mb flow retains a significant westerly component.
still...the low level offshore push should keep stratus away from the
shoreline almost completely mon night...especially n of the golden
gate. however...there will be an aftn seabreeze at the coast. max
temps on tue will not be much warmer inland than on mon but they
should warm up on the coast before the seabreeze kicks in. tda there
was a 52 degree spread between the coolest coastal spot (half moon
bay with a max of 58) and the warmest inland spot (bradley with a max
of 110). by mon that spread should be only a little more than half
as wide as the coast warms up 10-15 degrees and the interior cools 5-
10. we will probably see 10-20 mph ne winds in the e bay hills tue
mrng with possible gusts to 30...but the winds shouldnt be any
stronger than that due to the lack of upper support and an absence of
really steep surface pressure gradients. min temps will be cooler
in the hills the next 2 nights which should preclude really low
humidities.
the offshore flow will probably continue into tue night...but by wed
aftn the models increase onshore flow again and the eta brings a
southerly surge of fog/stratus up the coast. the 18z run had the
surge already up to pt reyes by 12z wed...this may be a little too
fast as is often the case with that model but by wed pm the surge
will become more likely and expect the clouds to return to most or
all of the coast by wed night. temps on wed should cool in most
coastal areas but not inland.
for the rest of the week the models retain a weak upper trof over
the district which should result in a fairly deep marine layer...a
moderate to strong onshore flow...and temps near or slightly
below normal.
&&
.aviation...the n-s gradient acv-sfo continues to increase tonight
and is currently 5 mb. the nam forecasts this to get up to 6-7 mb
monday. nw winds will increase over the coastal waters because of
this and also the stratus will likely stay along the immediate coast
and into monterey bay most of tonight. the upper trough passing to
our north will likely help mix out the stratus fairly quickly monday
morning as sfc high pressure builds in over nrn ca. lifr conditions
have moved in to ksns and kwvi...and it is now on the doorstep of
kmry. lighter winds and moist low levels at ksts will likely allow a
few hours of lowered vsbys and cigs there until winds kick up monday
am.
&&
.mtr watches/warnings/advisories
tngt...sca...point arena to pigeon point...and sfo bay.
&&
__________________________________________________________________________
Scott Hazen Mueller
Aug 29, 2005, 8:23:18 AM8/29/05
to
area forecast discussion
fxus66 kmtr 291209 aaa
afdmtr
area forecast discussion...updated
national weather service san francisco ca
updated aviation discussion
.discussion...an upper level low is moving inland over the pacific
northwest. surface high pressure is building into the pacific
northwest behind the trough. the n-s pressure gradient from acv-sfo
has increased to 5.0 mb. stratus is clearing out over the northern
coastal waters this morning though areas of it are still hanging on
along the coast...but these clouds should burn off early. the trough
passage has brought a cooler airmass to the district and temperatures
inland will be a few degrees cooler than sunday. most coastal temps
should not change much as increased sunshine will counteract the
airmass cooling. the surface high will build inland over the pacific
northwest today and we will be under a weak offshore flow tonight and
tuesday. this offshore flow is not expected to be strong as it is not
supported above 5000 feet...the flow aloft will be moderate west-
northwest. the offshore flow will keep the cwa stratus free tonight
except for some patches along the coast south of the san mateo coast.
temperatures will warm up everywhere in the cwa on tuesday...with
some areas like sts and santa cruz warming quite significantly due to
downslope warming from the offshore flow. the high will weaken and
move eastward and the offshore flow will gradually die off tuesday
night and wednesday. we then go into a benign weather pattern until
the next upper trough approaches the pacific northwest next weekend.
so look for gradually increasing coastal stratus later in the week
with temperatures slowly cooling...but staying near their normal
values.
&&
.aviation...increased nly flow down the coast...as well as cooler
temperatures aloft in response to an upper low moving into the
pacific nw and nrn ca...has helped to erode much of the stratus from
the coast. the stratus is holding on along the immediate coastline
from san mateo county southward including the mry bay and much of
the salinas valley...as well as locally into the n bay...sfo bay.
excpect a quick departure of any ceilings in the n and sfo bay
after sunrise...and a mid-morning burn off at kmry and ksns.
stronger onshore flow will bring gusty winds as high as 30 kt at
ksfo this afternoon and evening. there will be a limited return of
stratus tonight...if any...as offshore flow develops and brings a
drier airmass into the district.
&&
.mtr watches/warnings/advisories
tda...sca...point arena to pt piedras blancas and sfo bay.
&&
__________________________________________________________________________
public forecast: w pi
marine/aviation: kennedy
Scott Hazen Mueller
Aug 29, 2005, 2:23:17 PM8/29/05
to
area forecast discussion
fxus66 kmtr 291732
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...the upper level low over the pacific northwest
continues to move slowly eastward this morning with the trough
axis now at the coast. a weak surface trough off the washington
coast will give way to building high pressure starting this
afternoon. this high pressure will continue to build into the
pacific northwest and great basin through mid week. this will result
in a well pronounced thermal low over interior california beginning
on tuesday and lasting the next several days. winds over the
coastal waters have picked up. the n-s gradient has doubled from what
it was yesterday at this time. this combined with a weak northerly to
offshore flow near the coast have resulted in the stratus clearing
away almost entirely from the monterey bay northward. the stratus
still hanging around the monterey bay and northern salinas valley is
expected to clear by mid morning. as this pattern continues to set up
through tonight still expect the central coast to be pretty much
stratus free as stated by the earlier forecast discussion. as for
todays temperatures...the cooler airmass brought on by the trough is
well documented with most areas this morning experiencing cooler
temperatures over yesterday morning and in some areas double digit
cooler. however the cooler daytime highs expected today will warm up
again on tuesday as the thermal trough sets up. the models continue
to indicate very little change in the pattern through the end of the
week once the surface high settles into the great basin and the
thermal trough sets up over interior california. in the extended...
models are indicating the next possibility of some cooling this
weekend as a trough could approach the northwest coast again.
&&
.aviation...the marine layer remained shallow overnight...and
combined with a strong north to south gradient along the coast...
stratus coverage was reduced for the bay area. ksfo and ksjc did
not receive a ceiling at all last night...while koak only had a
ceiling from about 730z to 11z. the remaining bay area terminals
cleared out quickly by 16z.
low clouds have been cleared from most of the central california
coast...only small areas remain in monterey bay and south of point
sur. the north to south gradient will continue overnight along with
light offshore winds in some areas. with the coast already clear of
any extensive stratus deck...ceilings are not expected to return to
bay area terminals this evening.
onshore winds will be brisk this afternoon due to the upper level
trough passage...with gusts up to 30 kt at ksfo and up to 20 kt at
ksjc.
&&
.mtr watches/warnings/advisories
tda...sca...point arena to pt piedras blancas and sfo bay.
&&
__________________________________________________________________________
marine/aviation: sellers
Scott Hazen Mueller
Aug 29, 2005, 8:23:14 PM8/29/05
to
area forecast discussion
fxus66 kmtr 292355
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
.discussion...the upper level low over the pacific northwest is
moving inland this afternoon with the trough axis now at the san
francisco bay area. surface high pressure is starting to build toward
the pacific northwest behind this trough. models continue to build
the surface high pressure into the pacific northwest and great basin
through mid week and a thermal trough is expected to develop over
interior california. the n-s gradient has picked up slightly from
earlier today and now stands 6 mb from acv-sfo. satellite pictures
showing no clouds anywhere over the cwa. still expecting northerly
flow to set up inland tonight with the greatest effect over the north
and east bay hills. with this pattern do not expect any significant
stratus with the exception of a few patches at the coast and then
mainly south of san francisco. expect this weak offshore type
pattern to be most persistent the next twenty four hours. the
onshore pattern should strengthen after wednesday and expect a return
to more significant stratus for the end of the week and into the
weekend. as the thermal low develops temperatures should rebound
tomorrow from todays highs but not reach any record levels. longer
term models continue with a benign pattern the rest of the week and
still advertise bringing a trough into the pacific northwest on
saturday. if this holds we should see cooler temperatures and more
persistent stratus for the weekend.
&&
.aviation discussion...offshore flow will increase aloft overnight
as high pressure builds over or/nrn ca. the california coast is
already stratus-free this afternoon...and vfr conds are expected at
all area terminals overnight and into tuesday morning. some slight
concern for moderate low level wind shear near koak late tonight if
the offshore winds pick up enough across the east bay hills. left it
out of the taf for now...but certainly something to keep an eye on
during an otherwise very quiet night aviation-wise.
&&
.mtr watches/warnings/advisories
tngt...sca...point arena to pt piedras blancas and sfo bay.
&&
__________________________________________________________________________
public forecast: wjk
Scott Hazen Mueller
Aug 30, 2005, 2:23:13 AM8/30/05
to
area forecast discussion
fxus66 kmtr 300551
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
.discussion...it was cooler and breezy in most inland locations
across the bay area today...while it was somewhat warmer across
many coastal spots. a rather sharp upper level trof and
corresponding (yet weakening) cold front slipped through the bay area
this afternoon. while the surface-850mb front fizzled at our
latitude...the northerly gradient along the coast increased rapidly
behind the front...to a robust 8mb from sfo/acv early this evening.
the cooling aloft and strong surface winds helped wipe out the
stratus field from the entire state coastline...the first time we
could say that in quite awhile. impressive cold advection and
subsidence behind the trof is also helping mix down winds...causing
gale force winds in our northern waters and increasing winds across
the north bay hills. water vapor imagery this evening indicates nice
mid-level dry slot across norcal as a strong jet-stream plows across
50n.
short term concern is fire weather...as a red flag warning for napa
county was issued earlier today. expect northeast winds to increase
in the napa county hills around 09z and remain gusty until about 19z.
while upper support is not that strong...925mb winds off nam model
indicate steady 30mph overnight with expected relative humidity
recovery minimal. some gusty winds may develop late tonight as far
south as the east bay hills...but it should not last all that long.
a few patches of fog are expected to develop along the coast late
tonight...but with the lack of an organized marine layer and good
mixing...it should be short lived. a rapid warmup is in store for
inland locations tomorrow...with full sunshine and at least a full
morning of offshore winds. an afternoon sea-breeze should develop
near the coast...but if it is slow to develop...even many typically
cool coastal areas (half moon bay/pacifica) could bump up into the
lower 70s so have raised some gridded high temperatures in these
locations.
the warmup will continue inland on wed...but should halt at the
coast as a weak southerly flow develops near shore. however...
depending on timing...it could be another mild morning at most near-
shore locations before a stronger onshore flow develops in the
afternoon. as we head toward the end of the week...models indicate a
flattening of the pattern across california as the anamolously
strong upper low over the gulf of alaska spins jet energy toward
the pacific northwest. this should serve to once again deepen the
marine layer thu-fri and cool all areas at least a few degrees.
thereafter...depending on the strength and location of the trof
passage...we may be in for another period of weak offshore flow by
the later half of the labor day weekend. this would bring lots of
sunshine and near seasonable to perhaps slightly warmer than normal
readings to the district.
&&
.aviation...vfr conds will prevail across all area terminals tonight
as a hefty north-south pressure gradient keeps the coast stratus
free. will still need to keep an eye on the winds across the east bay
hills as low level wind shear is a possibility later tonight/tue am
near koak. at this point the threat of llws looks marginal at worst
so will keep it out of the taf for now.
&&
.mtr watches/warnings/advisories...
red flag warning...fire wx zone 265 tonight/tue morning.
gale warning ...point arena to pt reyes 0-20nm.
...point arena to pigeon pt 20-60nm.
small craft advisory...pt reyes to pt piedras blancas 0-20nm.
pigeon pt to pt piedras blancas 20-60nm.
&&
__________________________________________________________________________
public forecast: soroka
marine/aviation: weagle
Scott Hazen Mueller
Aug 30, 2005, 8:23:13 AM8/30/05
to
area forecast discussion
fxus66 kmtr 301136
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...the upper level trough is pushing east into idaho
and utah early this morning and in its wake surface high pressure is
building into the pacific nw and great basin. northerly gradients
have ramped up significantly today and the acv-sfo gradient it 7.5mb
at 09z while the e-w wmc-sfo gradient has just turned offshore in the
past few hours. the wmc-sfo gradient is 2.7mb at 09z but the nam and
gfs quickly increase this gradient to 8mb by 15z this morning. raws
sites across the north and east bay are just beginning to record n-
nne winds as high as 15 mph with gusts in the mid 20s at 09z...but
just to the north in lake county...knoxville creek raws is reporting
17 mph wind with gusts to 37 mph. the winds are expected to increase
over the north and east bay hills the next few hours with the
strongest winds around 15z. will continue the rfw in napa county
through 19z today as the strongest winds are expected here...and
monitor east bay raws for sustained winds exceeding red flag
criteria. most raws in the east bay have had rh`s as high as the low
to mid 40s overnight and sustained winds will need to exceed 20 mph
to meet red flag criteria.
aside from fire weather concerns at higher elevations...most of the
cwa will see a clear and warm day as the upper trough and strong
n-s gradient has mixed out the stratus along the coast. temperatures
should reach the 70s along the immediate coast...80s around the sfo
bay and low 90s well inland today. local w-e (sfo-sac) gradient
remains weak onshore (1.7mb) and will help contribute to a light...
late afternoon seabreeze. wednesday will likely be warm again as the
wmc-sfo gradient remains moderate offshore with only a little cooling
along the coast as the marine layer begins to re-establish itself.
offshore gradients really slack off wed night and the nam bl rh bring
a return to the stratus in earnest along the coast. the remainder of
the week will see the usual cool foggy conditions along the coast
with warm temperatures inland. another upper trough swings across the
pacific nw over the weekend however...medium range models are
suggesting the core of the trough will be farther north and offer a
weaker offshore flow...than the current event...in its wake early
next week.
&&
.aviation...strong n-s gradients will keep all area terminals
clear all day. local low-level wind shear is possible over the north
and east bay hills this morning.
&&
.mtr watches/warnings/advisories...
tda...red flag warning...fire wx zone 265 through noon.
sca...pt reyes to pt piedras blancas.
&&
__________________________________________________________________________
public forecast: kennedy
marine/aviation: w pi
Scott Hazen Mueller
Aug 30, 2005, 2:23:13 PM8/30/05
to
area forecast discussion
fxus66 kmtr 301743
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...with high pressure surging into the pacnw and the
great basin an offshore pattern has developed as forecast. at 8 am
the acv-sfo gradient was 6.6 mb...up from 5 mb at that time yda.
wmc-sfo had dramatically reversed to 7.6 offshore...yda it was 3.4
onshore. sfo-sac was still onshore but only by 1.1 mb...it was 2.7
yda. the n-s gradient extended down the cntrl coast with 2 mb sfo-
smx (0.9 n-s yda). as a result skies have cleared thru the entire
district and all areas will enjoy a warm...sunny day. its a beach
day.
the air aloft is only moderately warm and inland temps will be
mostly in the upper 80s and lower 90s...but it will not be much
cooler at the beaches with 70s in most places and probably 80s at
santa cruz. ne winds have developed in the e bay hills but
sustained speeds are only 10-20 mph in most places with humidities
in the 20s and lower 30s. these are only marginal red flag
conditions and the eta indicates that the winds will weaken and
shift to westerly this aftn so will not issue a warning for the
time being except for the existing one in napa county. that has
verified as ne winds are stronger up there. ne winds are forecast to
be weaker tngt...there is a distinct westerly component to the flow
aloft so although rh recoveries will be low in the hills winds should
be mostly light. the eta forecasts 9 mb wmc-sfo at 12z wed which
should be enough to generate 10-15 mph winds in some places but not
much more than that.
the air aloft is forecast to continue warming on wed...but by aftn a
stronger onshore flow is forecast to develop in coastal areas.
the n-s gradient will be weaker as well. max temps should thus be at
least as warm well inland on wed as tda but they will be cooler on
the coast...maybe much cooler in areas where the seabreeze develops
early. with the n-s gradient weakening...santa cruz is the most
likely spot for this to occur. the eta is not really forecasting a
clear cut southerly surge anymore...just a general filling in of
stratus along the coast thu mrng. this will set up general cooling
throughout the district on thu with onshore flow continuing to
strengthen...though the air aloft still does not cool appreciably.
after thu the district will go into a fairly cool pattern with an
upper trof persisting over the region thru labor day weekend...
accompanied by a moderate onshore flow. this will result in lots of
stratus...beginning fri mrng...and temps near or a little below
normal thru the weekend.
&&
.aviation...the bay area was under clear skies last night and remains
clear this morning. a strong north to south gradient...along with
light offshore flow...eroded away the marine stratus deck that
usually looms off the california coast. although the north-south
gradient and offshore flow will be weakening...do not expect low
clouds to return tonight. afternoon winds at bay area terminals will
be fairly light due to the offshore pattern.
&&
.mtr watches/warnings/advisories...
tda...red flag warning...fire wx zone 265 through noon.
&&
__________________________________________________________________________
public forecast: markkanen
marine/aviation: sellers
Scott Hazen Mueller
Aug 30, 2005, 8:23:15 PM8/30/05
to
area forecast discussion
fxus66 kmtr 310009
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
509 pm pdt tue aug 30 2005.discussion...its a beautiful aftn across the district with
absolutely no clouds anywhere...not even over the offshore waters.
havent had a day like this the entire month and we may not have had
one since june. with only a very weak onshore flow midaftn temps
were fairly isothermal over the region with mid 80s to lower 90s in
most places. it was a little cooler at the beaches but even there
most spots reached well into the 70s...it was even 73 at half moon
bay.
surface pressure gradients at 2 pm showed the offshore trend...
especially the wmc-sfo gradient which reversed dramatically from 7.7
mb onshore at that time yda to 8.3 mb offshore tda as high pressure
built strongly into the great basin in the wake of ydas upper trof
passage. this is right on schedule...usually these stronger trofs
start moving thru the area about sep 1. sfo-sac was only 1.1
onshore at 2 pm...down from 2.8 yda. however...changes are in the
works and this is already reflected in decreasing n-s gradients.
acv-sfo was 4.9 mb n-s...respectable but down from 6.2 mb yda. sfo-
smx was also down...to 1.5 from 1.9. the pt arena-piedras blancas
gradient was also decreasing...it was 1.9 mb n-s at 1 pm compared
with 3.3 yda.
the weakening n-s gradients herald the eventual end of the coastal
warm spell. we should still have clear skies tngt but the models
indicate that the coastal seabreeze will be stronger and earlier on
wed than tda...resulting in cooling near the ocean. with the air
aloft actually warming a little more...inland temps should be as
warm or slightly warmer than tda. the eta forecasts the stratus to
redevelop along the coast wed night. a couple days ago the model
was forecasting a southerly surge of stratus up the coast but now it
appears that the crud will simply develop wed night and edge up to
the coast in the increasing onshore flow.
this will set the stage for cooling over the entire district on thu
with temps cooling back to around normal. the eta forecasts the
stratus to come inland thu night as an upper trof deepens a little
over our region and the onshore flow becomes fairly strong. the gfs
then keeps this pattern in place thru the labor day weekend which
would give us temps around normal or a little below with fairly
extensive stratus. however...the euro forecasts higher 500 mb
heights sun/mon with stronger ridging over the swrn u.s...and that
model would keep our temps at normal or a little above. a compromise
between the two models keeps the wx right near climatology and that
seems the best solution for now.
&&
.aviation...the coast remains clear this afternoon due to continued
strong north-south pressure gradients across northern and central
california. vfr conds look to prevail at all area terminals once
again tonight and wednesday morning...with widespread stratus not
likely to return to the coast until wednesday/wednesday night.
&&
.mtr watches/warnings/advisories...
tngt...sca...pt arena to pigeon pt 20-60 nm out.
&&
__________________________________________________________________________
public forecast: markkanen
Scott Hazen Mueller
Aug 31, 2005, 2:23:25 AM8/31/05
to
area forecast discussion
fxus66 kmtr 310541
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
.discussion...it was a warm day today with temperatures quite
isothermal across the district...anywhere from the 70s along the
coast to 90s inland. there was one record temperature set today...
at sfo where it reached 87 which broke the record of 85 set in 1968.
tonight will remain clear with no marine layer to speak of and satl
imagery shows clear skies across california...with a little stratus
along the border with mexico.
the eta12 keeps skies clear tonight with high pressure over the
rockies. a weak trof edges to the coast late on wednesday. this
will help develop an inversion late in the day as inland h85 temps
incr from 21c to 24c. this will bring warmer temps inland and a
seabreeze to the coast w/cooler temps. stratus develops wednesday
night with a stronger onshore flow with coastal low clouds on
thursday.
current forecast looks good...no updates.
&&
along the coast...but the closest coastal stratus remains south of
lax airport. this should gradually begin to creep up the socal coast
later wednesday...but vfr conditions are expected to continue at all
sf/mry bay area terminals for the next 24 hours at least.
&&
.mtr watches/warnings/advisories...
tngt...sca...pt arena to pigeon pt 20-60 nm out.
&&
__________________________________________________________________________
marine/aviation: weagle
Scott Hazen Mueller
Aug 31, 2005, 8:23:14 AM8/31/05
to
area forecast discussion
fxus66 kmtr 311208 aaa
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...clear skies continue over the district overnight as
offshore continues aloft...however a hint of stratus redevelopment
is occurring off the san luis obispo county coast. the nam bl rh
represents the higher rh fairly well along their coast this morning
but it quickly dries out after sunrise...so expect sunny skies and
warm temperatures across the district again today. the local sfo-sac
gradient remains weak onshore at 1.5mb this morning while the n-s
gradient is weakening (acv-sfo at 3.7mb at 09z vs 7.5mb 24 hrs ago).
the larger scale wmc-sfo gradient remains moderate offshore...7.5mb
at 09z...but is expected to decrease though the day as high pressure
over the great basin weakens. the weakening gradients should allow
the seabreeze to begin a little earlier this afternoon allowing the
temperatures near the coast and bays to cool a few degrees over
yesterday. sfo airport reported a record high of 87f yesterday but
don`t expect any records today as the previous high on this date is
90f set in 1943.
fire weather continues to be the biggest concern across the district
this morning as weak offshore flow continues across the higher
terrain of the north and east bay hills. winds are considerably
lighter this morning than last...generally remaining below 8 mph...
however rh recoveries have only been in the 20-35% range this
morning due to the dry air aloft allowing conditions to border on
red flag criteria. however...winds at north and east bay raws sites
have begun to obtain a westerly component and expect this trend to
continue this morning with little or no increase in the wind speed...
so will refrain from issuing a red flag warning this morning. winds
will become westerly this afternoon bringing an increase in onshore
flow and improved rh recoveries for the remainder of the week.
the nam brings a return of stratus to the coast tonight as 850mb
temps warm to 22c today re-establishing the marine layer. increasing
onshore flow and deepening marine layer in response to another upper
trough digging out of the gulf of alaska will allow the stratus to
move farther inland thursday and friday nights. the upper low will
track across the pacific northwest saturday night and sunday with
sfc high pressure building into the pacific nw and great basin once
again...however medium range models indicate this low will not be as
deep and the offshore flow will be weaker than the present event.
&&
.aviation...vfr at airports this morning. sfo-sac gradient is light
onshore...currently 1.2 mb...and wmc-sfo is 7 mb offshore. light east
winds at blue canyon this am with dewpoint temps in the teens shows
dry air coming down off the sierra this morning. there is some
stratus & fog developing south of big sur at the moment. nw winds
observed out over the coastal waters but sfo-smx shows slight
southerly wind development in the last couple hours. the stratus
hugging the coast could work its way up around monterey peninsula
during the day...perhaps poised to come in to kmry and ksns by early
eve.
&&
.mtr watches/warnings/advisories...
tda...sca...sfo bay.
&&
__________________________________________________________________________
public forecast: kennedy
Scott Hazen Mueller
Aug 31, 2005, 2:23:17 PM8/31/05
to
area forecast discussion
fxus66 kmtr 311802
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...skies are completely clear over the district this
morning as the area enjoyed another night of offshore flow. latest
surface pressure gradients indicate a moderate offshore flow from
winnemucca to san francisco at 8.6 mb...and 3.2 mb between acv and
sfo but a weak onshore gradient with 0.4 mb from sfo-sac. satellite
imagery shows coastal stratus edging northward already to just west
of the monterey peninsula. the 12z nam boundary layer rh field does
hint at this moisture by 18z...and then along the entire coast
overnight tonight. however...the model does not indicate much inland
intrusion of the stratus by thursday morning...only locally into the
san francisco and monterey bay areas. more is expected by friday
morning as the onshore flow ramps up in response to slight deepening
of an upper level trough off the coast during the weekend. this will
produce a cooling trend into the weekend until weak ridging occurs
sunday and monday. medium range progs offer slightly different
solutions for early next week but most keep a long-wave ridge over
western canada through that time frame.
&&
.aviation...clear skies and light winds will persist through today
at area terminals. afternoon seabreeze will kick in after 20z.
stratus is working it way up the coast and is anticipated to move
into the monterey bay over the course of the day. kmry and ksns
will likely see ceiling by this evening.
&&
.mtr watches/warnings/advisories...
tda...sca...pt arena to pigeon point for seas...and sfo bay.
&&
__________________________________________________________________________
public forecast: anderson
marine/aviation: horne
Scott Hazen Mueller
Aug 31, 2005, 8:23:13 PM8/31/05
to
area forecast discussion
fxus66 kmtr 010003 aaa
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
503 pm pdt wed aug 31 2005.discussion...a tongue of stratus continues to edge northward up
the coast and is now past santa cruz and has almost reached the san
mateo county line per latest visible satellite imagery. coastal buoys
have switched to light southerly winds as the surface pressure
gradients tighten from south to north with 2.0 mb between santa
barbara and san francisco...and 2.2 mb from smx-sba. web cams along
the coast show gloomy skies at nepenthe at big sur as well as at
pebble beach...with low clouds in the vicinity of the cam at aptos...
and just visible over the water past mavericks. it is still sunny
inland throughout the cwa and afternoon temperatures are warmer than
yesterday at most sensor locations except for those along the
immediate coast like watsonville...which at 70 degrees is 15 degrees
cooler than at 2 pm on tuesday. afternoon temperatures are running
from the 70s at the immediate coast to the 80s and 90s inland.
stratus is expected to fill in over the coastal waters tonight and
spread locally inland by thursday morning...per the latest nam
boundary layer rh prog. stratus is then forecast to move farther
inland by friday morning as the onshore flow increases in response to
slight deepening of an upper level trough approaching the coast
during the weekend. this will produce a cooling trend into the
midweek for slight warming...mainly inland.
&&
.aviation...the northward surge of coastal low clouds and fog
continues along the san mateo coast this afternoon. this should
reach the golden gate by around 04z...but the marine layer should
remain fairly shallow tonight. as a result...low clouds should have a
hard time spreading south of the bay bridge...so kept ksfo ceiling-
free overnight with only tempo ceilings at koak between 12z-15z.
due to the southerly flow along the coast...the stratus should have
some difficulty getting into kmry as well.
&&
.mtr watches/warnings/advisories...
tngt...sca...pt arena to pigeon point 20-60 nm...and sfo bay n
of the bay bridge.
&&
__________________________________________________________________________
public forecast: anderson
Scott Hazen Mueller
Sep 1, 2005, 2:23:11 AM9/1/05
to
area forecast discussion
fxus66 kmtr 010522
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
.discussion...temps were hotter today in most locations with a
continuation of the weak offshore flow. the exception was santa
cruz...which was more than 10 degrees cooler with a light southerly
flow...ahead of the stratus that is moving up the coast. the flow is
gradually losing its offshore component.
vis imagery indc that the stratus continues to move up the coast...
now up to the middle of the san mateo coast. stratus is moving into
the salinas valley at this time. in fact...a low overcast was
reported in salinas and watsonville. with the southerly flow...
monterey has had a downslope flow which has kept the stratus out...
but that will change overnight. dew pts have increased significantly
with the onset of a weak southerly gradient from santa maria to san
francisco. the dew pt at santa rosa has increased from 28 at 6 pm
this time yesterday to 44 today...with a southeast wind. other
locations have had dew pt increases between 5 to 15 degrees.
models continue the cool down as a trof approaches the coast and
slightly deepens. stratus will continue to spread north along the
coast overnight. current forecast on track...no updates.
&&
.aviation...the northward surge of coastal stratus has reached the
golden gate and point reyes this evening...with low clouds and fog
streaming through the golden gate and into berkeley. however...the
marine layer appears to remain shallow...so low clouds will have
difficulty wrapping around the bay into ksfo. still going with tempo
ceilings at koak and tempo sct008 at ksfo between 12z-15z. as
expected with the southerly flow...ceilings have not affected kmry
yet...but as the marine layer slowly deepens...low clouds should
work their way over carmel hill and into kmry airport.
&&
.mtr watches/warnings/advisories...
tngt...sca...sfo bay north of the bay bridge.
...sca for haz seas...pt arena to pigeon pt 20-60nm out.
&&
__________________________________________________________________________
public forecast: strobin
marine/aviation: weagle
Scott Hazen Mueller
Sep 1, 2005, 8:23:08 AM9/1/05
to
area forecast discussion
fxus66 kmtr 011059
afdmtr
area forecast discussion
national weather service san francisco ca
prepared by forecasters at monterey nwsfo
350 am pdt thu sep 1 2005
a significant awips/gfe failure developed at monterey nwsfo late
wednesday night and early thursday morning. the electronic service
technician has been called in and is currently working on the
problem.
.discussion...light southerly winds along the coast continue to push
stratus and fog northward up beyond the golden gate bridge early this
morning. otherwise satellite shows clear skies over the forecast area.
a weak to moderate upper level high will stay over the forecast area.
onshore winds will help usher in slightly cooler air along the
immediate coast but inland temperatures will remain warm to hot with
90s common the next several days. an upper level trough will approach
the coast during the weekend...and this will help usher in more
stratus into inland valleys and may take the edge off the inland
valley heat...but probably not more than a couple of degrees. the
models show a weak upper ridge forming back over the area again from
sunday into the middle of next week...thus would expect to go back to
a warming and drier trend during this time.
.aviation...stratus surging up the coast but will only spread locally
inland this morning. oak and sts may see some occasional clouds
through 16z while at mry and sns the stratus is expected to stay in
until 17-18z.
__________________________________________________________________________
pi/canepa
Scott Hazen Mueller
Sep 1, 2005, 2:23:18 PM9/1/05
to
area forecast discussion
fxus66 kmtr 011743 aaa
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
900 am pdt thu sep 1 2005.discussion...stratus has returned to the coastal valleys this mrng
as onshore flow strengthens and the marine layer deepens. at 8 am
the acv-sfo gradient was dead flat...compared 3.2 mb n-s at that time
yda. sfo-sac was 1.7 onshore (only 0.4 yda). wmc-sfo was still
offshore but the 4.9 gradient was much weaker than ydas 8.6. temps
should be much cooler across the district tda...probably down 5-12
degrees in most areas.
the pattern developing now...a 500 mb trof over the w coast...is
forecast to continue for the next week...centered around a fairly
strong trof moving into the pacnw on sun. the euro and gfs are in
good agreement on this pattern...including the sun pacnw trof. a
couple days ago the euro forecast much less trofing over our region
this weekend but it has now fallen in line with the gfs which is the
reverse of the usual procedure. we should have normal to slightly
below normal temps thru the labor day weekend and beyond...with
plenty of night/mrng stratus.
&&
.aviation...stratus that infiltrated the bay area overnight is
burning off quickly. ksns and kmry will scatter out here shortly as
well. low clouds will persist along the coast through the day as a
result of a light onshore flow. stratus is expected to move back in
well after midnight tonight for the majority of bay area terminals
with the exception of ksns and kmry that will see ceilings around
02z.
&&
.mtr watches/warnings/advisories...
tda...sca...pt arena to pigeon pt 20-60 nm out and sfo bay.
&&
__________________________________________________________________________
public forecast: markkanen
marine/aviation: horne
Scott Hazen Mueller
Sep 1, 2005, 8:23:08 PM9/1/05
to
area forecast discussion
fxus66 kmtr 020014 aaa
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
.discussion...after 2 days of beach wx things are back to normal
across the district with a vast stratus field offshore and a
moderate onshore flow. at 1 pm the sfo-sac gradient was 1.8 mb...
compared to 0.9 yda. wmc-sfo was still offshore but only by 2.2 mb
vs. 7.8 yda. gradients along the coast were weak...ideal onshore
conditions. acv-sfo was only 1.1 n-s....3.6 yda...and pt piedras
blancas-pt arena was 1.3 s-n (1.6 yda). the marine layer was about
1500 feet deep.
the pattern setting up is a longwave 500 mb trof over the w coast
which will keep temps rather cool for at least the next week. the
gfs identifies two fairly strong trofs moving into the pacnw during
the period...one on sun and another next wed. the model forecasts
both of these features to bring enough cool air into our district to
break up the marine inversion with 850 mb temps at sfo at or below
plus 15 deg c...about the sea surface temp. at those times the
stratus field should become broken and we could see almost complete
clearing in the aftn on those two days...and maybe in between as
well as there will be only a slight warmup between the two systems.
thus...the next week will see max temps at normal or a little below
but there should be abundant sunshine during the aftn hours...even
at the coast on most days. on nights where the stratus coverage is
patchy due to the dissipating marine inversion we will probably see
quite a few min temps in the 40s at the usually colder spots such as
napa...santa rosa...hollister...and king city. this pattern shows
no signs of changing until next fri when a ridge may follow the
second strong trof into the region. the stronger trofs and weaker
marine inversions are right on schedule as we enter the sep/oct
sunny season at the beaches.
&&
.aviation...the marine layer and associated stratus remains well-
entrenched along the coast this afternoon. fort ord profiler is
back online and showing a marine layer around 1500 ft deep. some
slight deepening may occur overnight...and with healthy onshore
pressure gradients in place...stratus should make it into most
area terminals overnight. expect burnoff times around 18z at
koak/ksfo...possibly a little later if the marine layer deepens.
the stratus is already knocking on the doors of ksns and kmry...
those two terminals should have ceilings within the next couple of
hours.
&&
.mtr watches/warnings/advisories...
.tngt...sca...sfo bay n of the bay bridge.
&&
__________________________________________________________________________
public forecast: markkanen
Scott Hazen Mueller
Sep 2, 2005, 2:23:12 AM9/2/05
to
area forecast discussion
fxus66 kmtr 020546 aaa
afdmtr
area forecast discussion...updated aviation
national weather service san francisco ca
.discussion...an increased marine layer and a return to onshore flow
brought cooler temperatures to the entire district today...some
places by as much as 20 degrees as compared to yesterday`s highs.
high temperatures today ranged from the 60s at the immediate coast to
the 70s and 80s inland...with the very warmest areas reaching the
century mark.
temperatures are expected to continue on a gradual cooling trend
over the next several days as an upper level trough settles over the
pacific northwest. the marine layer...currently at 1600 feet...is
expected to deepen further as the upper trough digs as a series of
short waves moves through the main flow. these short waves...the
first one moving across the california coast friday night...and the
second one saturday night...could also cause episodes of coastal
drizzle at times.
early next week this trough is progged to move eastward however 500
mb heights are not progged to recover much over california as another
upper trough takes its place over the west. cool temperatures to
continue through the forecast period as the area remains under the
influence of an onshore flow.
&&
.aviation...the marine layer and associated stratus remains well-
into sfo/mry bays and adjacent coastal valleys. ifr ceilings are
already in place across koak/ksts/kmry/ksns. ksfo and ksjc should
get ceilings by sunrise. some slight deepening in the marine layer
has occurred over the past couple hours...and it is now up to 1800
ft deep. as a result...burnoff times may be slightly later than 18z
at ksfo and koak.
&&
.mtr watches/warnings/advisories...
.tngt...sca...sfo bay n of the bay bridge.
&&
__________________________________________________________________________
Scott Hazen Mueller
Sep 2, 2005, 8:23:07 AM9/2/05
to
area forecast discussion
fxus66 kmtr 021118 aaa
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...the district has shifted into a cool wx pattern with
an upper trof over the w coast. the marine layer is around 1800
feet deep and well defined. onshore flow is well established. at 2
am the sfo-sac gradient was 2.5 mb...strong for this time of day.
sfo-wmc was 0.5 onshore after being about 4 mb offshore at that time
yda. as is usual in good onshore patterns the gradients along the
coast are weak. acv-sfo was 2.3 mb n-s but smx-sfo was 0.3 s-n and
the pt piedras blancas-pt arena gradient was a gentle 0.7 s-n.
stratus has already filled the salinas...hollister...and santa clara
valleys as well as the 101 corridor thru all of sonoma county. max
temps will be below normal tda in most areas...60s on the coast and
no warmer than the lower/mid 80s at the well inland sites where
maxes are usually around 90 this time of year.
it will be even cooler on sat as the trof deepens over the district
and onshore flow remains strong. in fact...this pattern is set to
prevail thru the holiday weekend and the middle of next week. two
distinct shortwaves are forecast to move onshore during this
period...one on sun and the other next wed. these will bring enough
cold advection to weaken the marine layer which could result in the
dispersion of most stratus on those days...even along the coast.
stratus or not...temps will remain below normal except at the ocean
on sunny days. the gfs hints at some warming late next week but
doesnt advertise any kind of an offshore flow.
&&
.aviation...the marine layer has deepened to about 1500-2000 feet in
the last few hours. the stratus has moved inland during the night
with coverage getting fairly widespread. break out times near 18z for
the bay area airports looks good. a weak upper level trough will move
over the forecast area today...helping to deepen the layer but also
helping to mix the stratus back to the beaches in combination with
diurnal warming. moderate onshore surface winds will help usher the
stratus back inland later this evening.
&&
.mtr watches/warnings/advisories...
.tda...sca...sfo bay.
&&
__________________________________________________________________________
public forecast: markkanen
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...the district has shifted into a cool wx pattern with
an upper trof over the w coast. the marine layer is around 1800
feet deep and well defined. onshore flow is well established. at 2
am the sfo-sac gradient was 2.5 mb...strong for this time of day.
sfo-wmc was 0.5 onshore after being about 4 mb offshore at that time
yda. as is usual in good onshore patterns the gradients along the
coast are weak. acv-sfo was 2.3 mb n-s but smx-sfo was 0.3 s-n and
the pt piedras blancas-pt arena gradient was a gentle 0.7 s-n.
stratus has already filled the salinas...hollister...and santa clara
valleys as well as the 101 corridor thru all of sonoma county. max
temps will be below normal tda in most areas...60s on the coast and
no warmer than the lower/mid 80s at the well inland sites where
maxes are usually around 90 this time of year.
it will be even cooler on sat as the trof deepens over the district
and onshore flow remains strong. in fact...this pattern is set to
prevail thru the holiday weekend and the middle of next week. two
distinct shortwaves are forecast to move onshore during this
period...one on sun and the other next wed. these will bring enough
cold advection to weaken the marine layer which could result in the
dispersion of most stratus on those days...even along the coast.
stratus or not...temps will remain below normal except at the ocean
on sunny days. the gfs hints at some warming late next week but
doesnt advertise any kind of an offshore flow.
&&
.aviation...the marine layer has deepened to about 1500-2000 feet in
the last few hours. the stratus has moved inland during the night
with coverage getting fairly widespread. break out times near 18z for
the bay area airports looks good. a weak upper level trough will move
over the forecast area today...helping to deepen the layer but also
helping to mix the stratus back to the beaches in combination with
diurnal warming. moderate onshore surface winds will help usher the
stratus back inland later this evening.
&&
.mtr watches/warnings/advisories...
.tda...sca...sfo bay.
&&
__________________________________________________________________________
public forecast: markkanen
Scott Hazen Mueller
Sep 2, 2005, 2:23:11 PM9/2/05
to
area forecast discussion
fxus66 kmtr 021603
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...latest satl imagery...sfc obs...and web cams indc that
the stratus has made it well down the salinas valley...almost to
atascadero in san luis obispo county. low overcast covers most of
the sf bay area with the exception of concord. the ft ord profiler
shows that the marine inversion is near 1800 ft this morning.
the onshore gradient between sfo-sac is now 1.8 mb. the sfo-wmc
gradient is now nearly neutral...0.7 mb offshore down from 4.9 mb
offshore yesterday.
trof deepens over the weekend with a slow cooling trend. this pattern
continues through the beginning of next week.
current forecast looks good...no updates.
&&
morning per the fort ord profiler. with the deeper marine layer
came widespread intrusion of the stratus deck overnight. bay area
terminals will scatter out between 17-18z today while kmry and ksns
stay overcast a bit longer. status will work its way back inland this
evening under the influence of a moderate onshore push.
&&
.mtr watches/warnings/advisories...
.tda...sca...sfo bay.
&&
__________________________________________________________________________
marine/aviation: horne
Scott Hazen Mueller
Sep 2, 2005, 8:23:05 PM9/2/05
to
area forecast discussion
fxus66 kmtr 022148
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...low clouds have cleared from all areas except the
immediate coast per vis imagery and sfc obs. as of 1 pm the ft ord
profiler was showing that the marine layer has compressed to around
1400 feet.
temps are running several degrees cooler this aftn compared to
yesterday. the sfo-sac gradient is onshore at 1.8 mb...not much
different from yesterday.
water vapor imagery indc one shortwave moving onto the oregon coast
with another shortwave crossing 140w. a trof is off the coast
centered near 135w.
tonight through labor day...the trof moves into the pacific nw over
the weekend. cooler h85 temps move into the district. it is difficult
to say whether the h85 temps will be cool enough to wash out the
stratus deck. for now...will keep the stratus in...but less
extensive. temps will be pleasant over the holiday weekend with the
inland areas mostly in the 80s.
tuesday through the end of next week...another trof moves into the
pacific nw tuesday and wednesday continuing the cool weather.
weak ridging moves in from the pacific thursday and friday. the 12z
ecmwf is hinting at an offshore flow next friday as a surface high
moves into the northern intermountain west...however that is a week
away and things can change.
&&
.previous aviation...the marine layer is around a 1800-1900 feet deep
this morning per the fort ord profiler. with the deeper marine layer
came widespread intrusion of the stratus deck overnight. bay area
terminals will scatter out between 17-18z today while kmry and ksns
stay overcast a bit longer. status will work its way back inland this
evening under the influence of a moderate onshore push.
&&
.mtr watches/warnings/advisories...
Scott Hazen Mueller
Sep 3, 2005, 2:23:13 AM9/3/05
to
area forecast discussion
fxus66 kmtr 030552
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...much of the district was kept cool this afternoon
due to strong onshore pressure gradients and the resulting brisk
onshore flow that affected all but the most interior of locations.
some slight 500 mb height rises are occurring at the moment due to a
weak shortwave ridge sliding through central california. as a
result...the marine layer has compressed slightly down to around
1500 ft per the fort ord profiler.
aside from this weak shortwave ridge which should be gone by later
tonight...the overall trend will be for the longwave trof axis off
the west coast to inch closer to our coastline saturday and saturday
night. lower pressure (and 500 mb heights) aloft will allow the
marine layer to expand again later tonight and saturday. with the
marine layer expected to deepen to 2000-2500 ft...most of our cwa
should see some stratus the next two mornings. strong onshore flow
will keep high temperatures near or slightly below normal with inland
areas struggling to reach the lower to mid 80s...and the southern
interior cooling off to around 90 degrees. the current forecast
handles this well...so no updates are expected this evening.
gfs/ukmet/ecmwf/nam all bring in some sort of significant vort late
sat night/early sun am. this could be enough to squeeze some
drizzle out of the deep marine layer...especially over the coastal
hills. if the vort is strong enough and the airmass cools enough
aloft...the drizzle could be followed by the marine layer mixing
out later sunday. it will be a close call...which could either
result in a drizzly sunday in the 50s near the coast or a sunny day
with temperatures pushing 70.
in the extended...the overall troughiness sticks around the west
coast through midweek. temperatures should stay near or slightly
below normal with decent onshore flow and night/morning stratus.
there are some hints by the gfs/ecmwf that this pattern will begin to
break down late in the week...with ridging trying to nose into the
pacific northwest late thursday. if this occurs...we could be looking
at another moderate offshore flow event and potentially fire weather
issues by friday.
&&
.aviation...a strong n-s gradient is developing over northern
california while the gradients are flat or light s-n over central
california. the stratus has cleared off the coast north of the
golden gate but is expected to reform early saturday morning as the
gradients slacken off. this will delay the stratus getting into sfo
bay and sts until after 10z tonight.
&&
.mtr watches/warnings/advisories...
.tngt...sca sfo bay.
&&
__________________________________________________________________________
marine/aviation: w pi
Scott Hazen Mueller
Sep 3, 2005, 8:23:09 AM9/3/05
to
area forecast discussion
fxus66 kmtr 031134 aaa
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...although the district remains under the influence of
an upper level trof and 500 mb heights are decreasing slightly...
stratus is much less widespread this mrng than at the same time yda.
there is only a thin band along the coast and the clouds have not
moved far inland except up the salinas valley. however...the cloud
field is increasing offshore and still expect clouds to become more
extensive toward dawn. 2 am gradients included 3 mb n-s acv-sfo...
0.7 onshore sfo-wmc...2.8 sfo-sac...and 0.6 s-n smx-sfo. all these
numbers were within a millibar of ydas at this time and represent a
moderate onshore pattern.
the water vapor pix show an incoming shortwave trof distinctly as its
axis passes 140w...heading ewd. this feature is fairly deep for
this time of year...extending s to about lat 32...and it will move
thru our region on sun. the gfs forecasts 850 mb temps to drop to
around 15 deg c at sfo with the trof passage...close to the 13-15 c
sea surface temps over the coastal waters. the marine layer...
currently well defined at about 1400 feet at ft ord...may not
dissipate completely but it will become much less distinct and
expect all or almost all stratus to dissipate sun aftn with only
patchy coverage sun night. with the cool air aloft...areas without
clouds sun night will see temps drop to near the lowest levels of
the season. expect 40s in some areas especially at spots like santa
rosa...napa airport...king city...and hollister.
a weak upper trof will remain in place mon/tue with a slight warmup
over inland areas...and probably an increase in coastal stratus as
the marine layer becomes more distinct again. another shortwave
trof is forecast to move onshore tue night/wed. it will be quite
strong in the pacific nw and will probably disperse the marine layer
again in our district...leading to a sunny...cool aftn on wed.
after that the gfs and the euro raise 500 mb heights somewhat by fri
and develop a weak offshore pattern over the district...at least
from wmc to the coast. there will still be an aftn seabreeze near
the shoreline if the models verify but temps should trend warmer in
all areas thu and fri.
&&
.aviation...a lgt-mdt sw flow aloft exists ahead of a moderate
eastern pacific shortwave trough. the upper trough will help keep
stratus in along the coast...and locally into nearby coastal valleys
through this morning. ft ord profiler shows the marine inversion has
come down to about 1000 feet deep in the last few hours. will figure
burn-off times of stratus will be close to 18z. onshore winds will
pick up in the afternoon...locally gusty through the bay as the nam
model forecasts onshore gradients sfo-sac in the 4-5 mb range.
&&
.mtr watches/warnings/advisories...
.tda...sca sfo bay.
&&
__________________________________________________________________________
public forecast: markkanen
marine/aviation: canepa
Scott Hazen Mueller
Sep 3, 2005, 2:24:12 PM9/3/05
to
area forecast discussion
fxus66 kmtr 031614
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...the stratus has filled-in along the central ca coast
this morning and has worked into the north bay valleys and most of
the salinas valley. in the sfo bay the stratus is fairly wide spread
but appears thin on visible satellite south of san rafael to the
golden gate in marin county as well as south of burlingame to the
dumbarton bridge on the peninsula. the stratus should burn back to
the coast by mid-late morning as moderate onshore flow and a
deepening marine layer exists in advance of an upper level trough
approaching the pacific nw and nrn ca. onshore sfo-sac gradient is
stronger this morning (2.4mb up from 1.8mb yda 24h ago) while the
n-s (acv-sfo) gradient is also down 1mb to 1.8mb in the past 24 hrs.
the smx-sfo and wmc-sfo gradients are nearly flat at 0.4mb and 0.1mb
respectively. the marine layer has ramped up to 1800 ft this
morning per the ft ord profiler and the 12z koak sounding. the 850mb
temp has also cooled overnight from 20c at the 00z koak sounding to
18c at the 12z sounding...so expect inland temperatures to see a
couple degrees of cooling from yesterday. current forecast reflects
these trends and no updates planned.
the upper level trough axis will move across nrn ca tonight with
another short wave trough moving through sunday night. the broader
long wave trough is progged by the medium range models to remain
over the ern pac and west coast through mid week with onshore flow
and cooler temps aloft continuing. latest nam and gfs model run
keeps 850mb temps around 16-18c through this time which could help
dissipate the stratus somewhat...but expect at least patchy stratus
will remain near the coast. a stronger upper trof moves across the
pac nw and nrn ca tue into wed providing additional cooling which
may break up the stratus even more. after this last trof passage...a
broad upper ridge is progged to build across the state from the ern
pac while offshore flow briefly develops at the sfc behind the
departing upper trof. 850mb temps quickly rise to 20c on thu and
continue for the remainder of the week providing a warm-up for
inland locations...and possibly for coastal areas thu and maybe
into friday depending on the strength of the offshore flow.
&&
.previous aviation discussion...a lgt-mdt sw flow aloft exists ahead
of a moderate eastern pacific shortwave trough. the upper trough will
help keep stratus in along the coast...and locally into nearby
coastal valleys through this morning. ft ord profiler shows the
marine inversion has come down to about 1000 feet deep in the last
few hours. will figure burn-off times of stratus will be close to
18z. onshore winds will pick up in the afternoon...locally gusty
through the bay as the nam model forecasts onshore gradients sfo-sac
in the 4-5 mb range.
&&
.mtr watches/warnings/advisories...
.tda...sca sfo bay.
&&
__________________________________________________________________________
marine/aviation: canepa/sellers
Scott Hazen Mueller
Sep 3, 2005, 8:23:20 PM9/3/05
to
area forecast discussion
fxus66 kmtr 032123
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...stratus continues along most of the coastline this
afternoon and extends into the mry bay as well as the sfo bay
through the city across to berkeley. a stronger onshore gradient
(sfo-sac at 2.6mb at 20z vs 1.5mb yda) and deeper marine layer
(1800ft per the ft ord profiler) has contributed to keeping the
stratus along the coast and locally into the bays. an upper level
trof continues to dig southward and the axis is crossing 135w. an
upper level jet streak in advance of the trof is spreading mid-high
level cloudiness across nrn ca and pacific nw this afternoon and
the tail end of the clouds may skirt the nrn areas of the cwa
overnight...otherwise skies will remain clear aside from stratus
along the coast. nam and gfs keep 850 mb temps around 16-18c through
tue which may not be enough cooling aloft of completely wipe out
the marine layer...however the upper trof will remain across the
west coast providing seasonable to slightly below seasonable temps
across the region.
the latest runs of the medium range models dig another trough across
the region on wednesday with 500 mb heights down to 574dm...deeper
than the previous run. the gfs brings 850mb temps down to 13c wed
likely dissipating the marine layer...and expect a nearly
isothermal...fall like day on wed. surface high pressure will build
into the pacific nw and great basin thu and friday bringing offshore
flow and much warmer temps across the district.
&&
.previous aviation discussion...the deeper marine layer and stronger
onshore flow has resulted in a later burn-off time for bay area
terminals. ksts...kmry...and ksns still remain under low clouds at
18z. clearing for these terminals is expected by 19z at the latest. a
large area of stratus also remains over the san francisco bay...
however koak and ksfo have already scattered.
brisk onshore flow will allow winds at ksfo to gust up to 20 kt
this afternoon. with the upper level trough passage...the marine
layer will remain deep and onshore flow will continue during the next
24 hours. all bay area terminals will have ceilings tonight...with
slightly earlier onset times compared to last night. monterey bay
area terminals kmry and ksns will see low clouds return this
evening...and san francisco and north bay area terminals will be
affected by low clouds around midnight.
&&
.mtr watches/warnings/advisories...
.tngt...sca sfo bay.
&&
__________________________________________________________________________
public forecast: kennedy
Scott Hazen Mueller
Sep 4, 2005, 2:23:14 AM9/4/05
to
area forecast discussion
fxus66 kmtr 040253
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...it was cooler...especially inland today with h85 temps
a bit cooler. stratus remained along the coast most of the day and
is starting to move back into sf bay where oakland is reporting a
ceiling. the marine layer is starting to deepen per the ft ord
profiler as a trof off the coast moves east...and a weak wave
approaches 38/125...just off the northern ca coast. the onshore
gradient between sfo-sac is a little stronger today...3.4 mb
compared to 3.0 mb yesterday.
models continue to bring the trof slowly to the coast over the
holiday weekend...along with weak waves ejecting through the trof.
this will continue to deepen the marine layer and drive the stratus
even further inland. it is possible that there will be enough
cooling aloft to mix out the stratus...but for now it seems like
the low overcast will continue. with the deeper marine layer...it is
certainly possible that there could be some morning drizzle.
either way...temps will be near to below normal...especially inland.
current forecast looks good...no updates.
&&
to spread into oak and sfo very early this evening. stratus has
been over oak since 01z and will spread into sfo by 04z. sts and sjc
will see stratus earlier than they normally would as well. marine
layer expected to deepen overnight and this will keep stratus in
over the sfo approach zone through 18z at least.
&&
.mtr watches/warnings/advisories...
.tngt...sca sfo bay.
&&
__________________________________________________________________________
marine/aviation: w pi
Scott Hazen Mueller
Sep 4, 2005, 8:23:21 AM9/4/05
to
area forecast discussion
fxus66 kmtr 041112
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...a shortwave is approaching the district from the w...
sliding into the mean trof position over the w coast. the marine
layer has deepened to around 2000 feet. although stratus coverage
is patchy offshore...clouds have spread into most valleys throughout
the district. a band of high clouds associated with the shortwave
is passing thru the n bay. with some cold advection from this
feature the marine layer will become somewhat indistinct tda and
expect most if not all stratus to disperse this aftn...leaving a
sunny and somewhat cool day over the district with temps below
normal.
onshore flow continues fairly strong. at 2 am the sfo-sac gradient
was 2.6 mb...with 2.4 onshore sfo-wmc. acv-sfo was 2.8 mb n-s with
1 mb s-n smx-sfo and 1.8 s-n pt piedras blancas-pt arena. on mon
the onshore flow is forecast to weaken somewhat as 500 mb heights
increase a little...and we should see slight warming in most places.
the coast may not share in the warming as the warmer air aloft will
sharpen the marine layer...making stratus more persistent near the
ocean.
tue will be similar to mon...maybe a couple degrees warmer again
inland. by wed the 00z euro and gfs both drop a shortwave s down
the coast and develop it into a cutoff low very close to the bay
area. this is an odd solution...especially for this time of year.
it would be more feasible in the spring. however...the last two
runs of the euro and gfs have had this solution and the 00z runs of
the uk and canadian also feature a cutoff low in the area...though
the canadian has it offshore out near 130w. with such agreement and
continuity we will have to take the models seriously. this cutoff
would bring in enough cool air aloft to wipe out the marine layer...
leaving a brisk but mostly sunny aftn over the region on wed with
only patchy stratus wed night. max temps on wed should be almost
all below 80 in the bay area...even well inland.
the cutoff is forecast to be progressive and move e of the region by
fri which would allow a warmup. however...the weak offshore flow
forecast by the gfs yda is not depicted as clearly now. the 00z gfs
still has a hint of it...along with significant airmass warming...
but the 06z dgex has given up on the idea. the euro now drops a
strong inside slider shortwave into the great basin by sat which
would preclude much warming fri/sat though the coast could warm up
after that if an offshore flow developed in the wake of the slider.
for now will warm temps up somewhat on fri and sat but only to about
normal.
&&
.aviation...the stratus has moved into the bay area and down the
salinas valley this morning. a weak upper trough will move across
the bay area during the day...helping to keep stratus banked up along
the coast after the usual burn off back to the ocean. stratus is
once again likely to burn off around 18z-19z at area airports.
&&
.mtr watches/warnings/advisories...
.tda...sca...sfo bay.
&&
__________________________________________________________________________
public forecast: markkanen
marine/aviation: canepa
Scott Hazen Mueller
Sep 4, 2005, 2:23:09 PM9/4/05
to
area forecast discussion
fxus66 kmtr 041612
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...the 12z oak sounding and bay area sodar data indicate
the marine layer depth is at about 2000 feet...a couple hundred feet
deeper than yesterday morning. the oak sounding and higher elevation
temperature sensors are showing slight cooling aloft. these changes
are in response to the shortwave trough aloft that is presently
moving across northern and central ca. the relatively deep marine
layer and moderate onshore flow has allowed marine air to move well
inland overnight and cooler daytime highs would normally be the
result. however...cooling aloft has weakened the marine
inversion...possibly enough to result in earlier clearing today.
thus...temps likely will not cool much today and in all likelihood
will warm a bit in some coastal spots if earlier clearing occurs as
anticipated. current forecast is on track with present thinking and
no morning updates are planned.
in the longer range...temps are expected to remain on the cool
side...particularly inland...as the longwave trough position is
forecast to remain along the west coast. there are some
dissimilarities among the models as to when and where a cutoff low
will develop in the mid-week time frame and how that cutoff may
affect our weather. will address this in more detail in the
afternoon forecast package.
&&
.aviation...stratus has cleared from the southern sfo bay and sfo
approach bringing visuals early this morning. however...the stratus
is fairly extensive north of the bay bridge and into sonoma and napa
county valleys...as well the monterey bay area...down the salinas
valley and into hollister and southern santa clara valley. expect
a late morning clearing (18-19z) at ksts...kmry and ksts.
&&
.mtr watches/warnings/advisories...
.tda...sca...pt arena to pigeon pt and sfo bay.
&&
__________________________________________________________________________
public forecast: dykema
marine/aviation: kennedy
Scott Hazen Mueller
Sep 4, 2005, 8:23:11 PM9/4/05
to
area forecast discussion
fxus66 kmtr 042329
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...passage of an upper level shortwave trough last night
and this morning weakened the marine inversion enough to produce the
necessary low level mixing to clear out much of the coastal low
clouds. by mid afternoon only a small portion of coastline near the
golden gate was still overcast and satellite imagery indicated this
area was clearing as well. even with cooling aloft...more sun today
resulted in slightly warmer temps in many areas...especially near the
coast. expect areas of coastal stratus to redevelop overnight as the
airmass becomes more stable and moderate low level onshore flow
continues. but the nam forecasts less widespread low cloud coverage
tonight and monday morning than what we`ve experienced the past
couple of days and this seems reasonable given the current clearing
trend. daytime highs will be slightly warmer on labor day...and
probably tuesday as well...due to reduced cloud cover and airmass
warming as heights and thicknesses slowly rise. however...coastal
temps may start to dip again by tuesday if the marine inversion
strengthens as anticipated and low clouds become more widespread and
persistent at the coast. more significant and widespread cooling is
likely by wednesday and thursday as both the gfs and ecmwf models
agree that an upper trough will dig south along the west coast and
form a cutoff near the bay area by wednesday night. inland areas will
see the most cooling wednesday and thursday. the coast...however...
may experience little or no cooling if sufficient cooling occurs
aloft to disrupt the marine inversion and clear out the low clouds
once again.
in the longer range...the 12z operational gfs forecasts another
trough to dig south along the coast late friday into the weekend.
but this one is forecast to be much deeper than the mid week
system. in fact...if the operational gfs were to verify...500 mb
heights would drop as low as 558 dm by saturday night and rain
showers would develop across the region during the weekend. the
12z ecmwf forecasts next weekend`s system to be more of an inside
slider type...which would mean dry conditions and less significant
cooling. the ecmwf is the favored model at this point since its
solution is more realistic for this time of year. also...several 12z
gfs ensemble members look similar to the euro. for now will forecast
cooling next weekend but hold off on any precip.
&&
.aviation...stratus has cleared from the entire cwa this
afternoon as the upper trough moved through the district. the
inversion is still there at 2000 feet so expect the stratus to
reform along the coast after sundown with ceilings over mry and sns
after 04z. the stratus will spread into the sfo bay area late
tonight well after the evening rush hour.
&&
.mtr watches/warnings/advisories...
.tngt...sca...pt arena to pt piedras blancas and sfo bay.
&&
__________________________________________________________________________
public forecast: dykema
Scott Hazen Mueller
Sep 5, 2005, 2:23:14 AM9/5/05
to
area forecast discussion
fxus66 kmtr 050527
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...temperatures today were similar to yesterdays as a
weak shortwave moves over the pacific northwest. temperatures today
in the sf bay area ranged from a high of 86 in cloverdale to a
chilly low of 44 in la honda. in the southern portion of the
district the high was 94 in parkfield with a low of 43 in fort
hunter liggett.
water vapor imagery indicates a weak vort max moving into nw
california. a combination of the vort max and cooler air aloft...as
well as a deeper marine layer near 2000 ft at oakland at 00z...
helped mix out the stratus. latest fog imagery shows little stratus
along the coast.
as the vort passes by tonight the atmosphere should stabilize with
the marine layer compressing somewhat. this will lead to the
development of stratus along the coast. latest 00z run of the nam
indc that a flat ridge will dominate the weather for the next
couple of days. could be a bit warmer inland...especially southern
monterey and san benito counties.
the weather could be interesting next weekend with the gfs dropping
a closed low over the district with h85 temps 6-8c. the 12z ecmwf
indc that an inside slider type system will move into the west.
before jumping on the gfs bandwagon will have to see how consistent
the model is...since it would be unusual to have such a deep system
so early in september.
current forecast looks good...no updates.
&&
night and thus the stratus has yet to form along the coast as
of 10 pm sunday. but an inversion still exists at 2000 feet so expect
the stratus to reform along the coast and spread into sfo bay by
sunrise monday. the stratus is expected to burn off by 17z.
&&
.mtr watches/warnings/advisories...
.tngt...sca...pt arena to pt piedras blancas and sfo bay.
&&
__________________________________________________________________________
Scott Hazen Mueller
Sep 5, 2005, 8:23:12 AM9/5/05
to
area forecast discussion
fxus66 kmtr 051139 aaa
afdmtr
area forecast discussion
national weather service san francisco ca
updated aviation
.discussion...its a clear...cool mrng across the district tda as the
weekend upper trof has rendered the marine layer deep but indistinct
with moisture dispersing within it. the nearest stratus is dropping
swd on the wrn edge of our outer waters...about 60 nm offshore. its
still possible that a few patches of stratus could form over land
toward dawn but with 2 am temp/dp spreads of 3-8 degrees f at most
sites...cloud cover should be very patchy if any forms at all. a
sunny fcst should be ok...with max temps a little warmer than yda as
the airmass will warm slightly.
the surface pressure pattern also favors slight warming. at 2 am
the onshore flow was a little weaker than yda. sfo-sac was 2.1 mb
(2.6 yda) and sfo-wmc was 1.2 onshore (2.4). although the acv-sfo
gradient was identical to yda at 2.8 n-s...the northerly flow had
spread to the central coast by this mrng. sfo-smx was 1.1 n-s
compared to 1 mb s-n yda...and at 1 am pt arena-pt piedras blancas
was 1.2 n-s (1.8 s-n yda). this trend is also favorable for slight
warming tda.
on tue the 850 mb temp goes up about 1 deg c at sfo but other wx
parameters remain about the same...suggesting a little warming
inland but probably not at the coast. we should see some stratus
tngt/tue night as the marine layer will become a little more
distinct but the eta still suggests it will not form an extensive
cloud field.
after tue we have a couple of wx systems to deal with. for 2 days
the gfs has been bringing a deep little cutoff low right over the
sfo bay area on wed. this looks odd but the model has been
consistent with it and the euro has a similar idea though it drops
the cutoff into the bay area a little more slowly than the gfs. the
canadian and uk also have a cutoff in the vicinity so it probably
will happen...resulting in sharply cooler temps over the interior on
that day with the marine layer mixing out again. the models are in
dispute on how fast the cutoff will move ewd out of the area with
the euro and uk slower than the gfs...and probably better since we
are dealing with a cutoff.
after a couple days of cyclonic nwly flow aloft on thu and fri the
models drop a big positive tilt trof into the wrn u.s. next
weekend. though the models have depth and timing differences they
all have this system. the gfs has it the deepest and farthest w...
swinging the trof axis onshore on sun with strong digging all the
way into srn ca. this is probably overdone...it would be very
unusual for such a system to slam into la and san diego in the first
half of sep. the euro solution is probably more feasible but even
that one is unseasonably strong. the gfs solution has much more
overwater trajectory and would give us a chance of rain on sun while
the euro is in more of an inside slider configuration. will use the
euro and make a forecast of partly cloudy and cool sat/sun...but dry.
&&
.aviation...it is less humid over the area this morning thus there is
very little stratus development occuring. there may be a few patches
along the immediate coast early this morning but this should burn off
quickly. some drier air is working its way downward to the surface as
dewpoints have lowered a few degrees. onshore winds will pick up a
bit by late morning and continue into the afternoon.
&&
.mtr watches/warnings/advisories...
.tda...sca...pt sur to pt piedras blancas and sfo bay.
&&
__________________________________________________________________________
public forecast: markkanen
marine/aviation: canepa
Scott Hazen Mueller
Sep 5, 2005, 2:22:57 PM9/5/05
to
area forecast discussion
fxus66 kmtr 051820
afdmtr
area forecast discussion
national weather service san francisco ca
.discussion...a beautiful morning across the central coast with
abundant sunshine aside from a couple patches of low clouds...one
area near the golden gate and the other in the center of the
monterey bay stretching over to moss landing. temperatures should be
similar to yesterday...maybe a couple degrees of warming as the
airmass warms slightly. the 12z koak sounding temps were 16c...and
the nam and gfs warm 850mb temps to near 18c this afternoon.
tue will be similar to today with a couple degrees of warming inland
again as the temps aloft warm a degree or two with southwest flow
developing aloft ahead of the next trof dropping south out of the
gulf of alaska. the trof develops a cut-off low over nrn ca on
wednesday bringing cooler temperatures across the region. models are
in slight disagreement as to where the core of the cutoff be wed
night with the gfs the deepest having the core over the sfo bay
while the nam slides the core of the low across the nrn sac vly and
the lake tahoe region. both solutions keep dry conditions across
the district but the gfs will bring the greatest cooling.
thu and fri will be slightly warmer as shortwave ridging builds
behind the departing cut-off but medium range models drop an even
deeper low southward out of the eastern gulf of alaska next weekend
and a couple solutions even develop precip across the district. the
euro trajectory is more of an inside slider which would bring a
drier system across the state with no precip likely. since it is
very early in the season to develop such a deep system...will stay
with current thinking of the euro solution at this time and keep
precip out of the forecast until models come into better agreement.
&&
.aviation...hints of stratus are developing along the coast this
morning. a small patch developed in the monterey bay earlier today
but should dissipate by noon. another small patch is developing
just south of point reyes. skies will remain clear through the day
however patchy stratus will develop late this evening and move
locally inland. kmry and ksns will see ceiling around midnight while
koak and ksfo will see a broken ceiling around sunrise. expect the
afternoon seabreeze will kick in once again today and persist
through the evening.
&&
.mtr watches/warnings/advisories...
.tda...sca...pt sur to pt piedras blancas and sfo bay.
&&
__________________________________________________________________________
marine/aviation: horne
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