Fw: [mbfhga] Marina Convergence (Shear) Discussion
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Steven Espinosa
Jun 2, 2010, 9:46:57 AM6/2/10
to Coastal Condors, hbur...@pacbell.net
----- Forwarded Message ----
From: Harry <hbur...@pacbell.net>
To: mbf...@yahoogroups.com
Sent: Tue, June 1, 2010 3:57:10 PM
Subject: [mbfhga] Marina Convergence (Shear) Discussion
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From: Harry <hbur...@pacbell.net>
To: mbf...@yahoogroups.com
Sent: Tue, June 1, 2010 3:57:10 PM
Subject: [mbfhga] Marina Convergence (Shear) Discussion
I've a question for those who have flown a Marina shear (a visible one - with wave cloud(s) present). Did the wave cloud(s) seem to form south of Marina, perhaps near the Monterey Peninsula and then gradually propagate NE-ward to reach Marina beach as the soarable convergence developed? Any/all first hand descriptions, observations, and thoughts about the generation and evolution of the Marina shear are welcome.
Thanks,
Harry
--- In mbf...@yahoogroups.com, Steven Espinosa <stevenmespinosa@...> wrote:
>
> Harry,
> Was at Marina 31 may, the low level stratus deck was over Marina, shutting off soarable conditions. It did look like the "convergence" cloud with the leading edge further west.
>
> Steve
>
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Stephen Wasson
Jun 2, 2010, 10:39:01 PM6/2/10
to coastal...@googlegroups.com
Most, but not all, shears I've been in were in a cloud line
from PG to Marina (SW-to-NE). It seems to me that they occur with a
WNW wind rising up and over a WSW flow. This is evident when in the
shear, there are strong, cold, headwinds from the WNW, and when
falling through down onto the deck, there are light, warm, winds from
WSW. The highest shear I was in (2500'), winds were blowing WNW@22,
and when I finally dropped out of it, I was in due S@10. It also
seems to me that, once they set up, they move slowly to the
North.
That said, I've also been in smaller shears with somewhat the reverse scenario: where it was totally fogged in at Marina, and only after flying all the way to Sand City did I break out into the sun and climb up to 700'. The shear line was on the edge of the fog. Again, that line was basically from Monterey (the town) to Sand City, but that time it was sunny to the south and cloudy to the north.
One key thing to know is, if you see someone in a shear, DON'T just fly straight to underneath them. That would be under the wave, i.e. in the wrong wind. Do that, and you'll likely end up on the deck. Instead, fly slowly enough to detect any hints of better-than-normal lift. Sometimes you have to actually spend a little time slowly benching up a few hundred feet before it becomes obvious that you've found the elevator.
Another thing I think is usually true is that shears generally cross the beach in only one place, especially if they're well defined. If you can see the cloud, I'd guess that the crossing is at about a 45 degree slope to the beach. For example, if the cloud looks like it's crossing over Stillwell, then on the deck, the wave is probably crossing the beach somewhere near Lake Court (depending on cloud height and angle too the beach).
The visible shears I've been in have often been preceded by visible haze domes marking their edge. Just like 'block off' marks where the winds skip up and over (where the whitecaps stop), the haze domes can have similar wind lines. I've also seen shear clouds where, once the wind line pushed in, winds went from 10 to over 30. That's what you'd be in, and at the shear top, that'd be 30+ laminar, i.e. you're going to be pulled in and probably going down (into the crap).
I've also heard it said (but never been foolish enough to test it like some people I know who shall remain nameless) that "going over the back" is asking for trouble--big time rotor I'm told.
That said, I've also been in smaller shears with somewhat the reverse scenario: where it was totally fogged in at Marina, and only after flying all the way to Sand City did I break out into the sun and climb up to 700'. The shear line was on the edge of the fog. Again, that line was basically from Monterey (the town) to Sand City, but that time it was sunny to the south and cloudy to the north.
One key thing to know is, if you see someone in a shear, DON'T just fly straight to underneath them. That would be under the wave, i.e. in the wrong wind. Do that, and you'll likely end up on the deck. Instead, fly slowly enough to detect any hints of better-than-normal lift. Sometimes you have to actually spend a little time slowly benching up a few hundred feet before it becomes obvious that you've found the elevator.
Another thing I think is usually true is that shears generally cross the beach in only one place, especially if they're well defined. If you can see the cloud, I'd guess that the crossing is at about a 45 degree slope to the beach. For example, if the cloud looks like it's crossing over Stillwell, then on the deck, the wave is probably crossing the beach somewhere near Lake Court (depending on cloud height and angle too the beach).
The visible shears I've been in have often been preceded by visible haze domes marking their edge. Just like 'block off' marks where the winds skip up and over (where the whitecaps stop), the haze domes can have similar wind lines. I've also seen shear clouds where, once the wind line pushed in, winds went from 10 to over 30. That's what you'd be in, and at the shear top, that'd be 30+ laminar, i.e. you're going to be pulled in and probably going down (into the crap).
I've also heard it said (but never been foolish enough to test it like some people I know who shall remain nameless) that "going over the back" is asking for trouble--big time rotor I'm told.
At 06:46 AM 6/2/2010, you wrote:
----- Forwarded Message ----
From: Harry <hbur...@pacbell.net>
To: mbf...@yahoogroups.com
Sent: Tue, June 1, 2010 3:57:10 PM
Subject: [mbfhga] Marina Convergence (Shear) Discussion
I've a question for those who have flown a Marina shear (a visible one - with wave cloud(s) present). Did the wave cloud(s) seem to form south of Marina, perhaps near the Monterey Peninsula and then gradually propagate NE-ward to reach Marina beach as the soarable convergence developed? Any/all first hand descriptions, observations, and thoughts about the generation and evolution of the Marina shear are welcome.
Thanks,
Harry
--- In mbf...@yahoogroups.com, Steven Espinosa <stevenmespinosa@...> wrote:
>
> Harry,
> Was at Marina 31 may, the low level stratus deck was over Marina, shutting off soarable conditions. It did look like the "convergence" cloud with the leading edge further west.
>
> Steve
>
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Stephen Wasson
Secretary/Treasurer
Coastal Condors, Marina CA
USHGA Chapter 084 (aka 136)
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