WEATHERAmerica Newsletter, Saturday, April 1, 2017 at 8:40 P.M. CT (Near Term Forecasts)

[Larry Cosgrove]

SHORT RANGE OUTLOOK

(Through The Next 72 Hours)

Severe Weather Outbreak Indicated For Texas And Old South; Ohio Valley And Mid-Atlantic Regions May Also Be Affected

NOAA/SPC

NRL

University Of Wisconsin Weather Server (3)

TwisterData.Com (3)

UQAM Weather Centre (3)

TropicalTidbits.Com (Levi Cowan) (2)

A disturbance slowly organizing over the southern Rocky Mountains could have great impacts on much of TX, the Old South, and Mid-Atlantic region during the course of the near term. While seemingly disorganized on Saturday evening, the storm will consolidate over S OK on early Sunday, with the upper core of the system phasing with the subtropical jet stream impulse coming out of northern Mexico. There are two inherent dangers with this disturbance. One is, due to its initially slow forward motion, there may be repeated rounds of intense thunderstorms across Texas into the Ozark Plateau and "Arklatex" vicinity. Another concern is when the system undergoes  a"bolting phase", where acceleration occurs Sunday night. 

Since a Mesoscale Convective System formation over the eastern half of Texas is indicated by most of the numerical models, probably later Sunday, the phased system may inject an impressive amount of moisture, energy, and surface air mass convergence into the Deep South on Monday. The greatest risk potential for tornadoes will be over SE TX on Sunday afternoon and evening, spreading into the western half of LA. The surface low center most likely will head northeastward into the Ohio Valley, The high-impact upsurge of vertical motion may transition the MCS into a fragmented squall line of sorts that roughly parallels the Appalachian Mountains on Monday afternoon and evening. The elevated areas may further fragment that line, so discrete thunderstorm cells may redevelop over the Atlantic Coastal Plain on Tuesday, when the low moves through the lower Great Lakes into the Laurentian Shield. So at this time, I suspect that further convective outlooks may have to be upgraded for much of Dixie, and perhaps parts of the Virginias and Mid-Atlantic states as well. The entire system should be out of the U.S. on late Tuesday night.

Another Disturbance Passing Through Intermountain Region May Replicate Convective Threat In Great Plains And Lone Star State By April 5

Dundee University

PivotalWeather.Com (3)

ECMWF

This being an active pattern, it should come as no surprise that a new disturbance and frontal structure will appear over the West quickly after the early week system lifts out. The next impulse in the series looks quite strong (now entering the Gulf of Alaska), and will dig very sharply into California and the Great Basin on Tuesday. The high-impact cold dome will be small, but concurrent with abundant vorticity and a divergent pattern aloft may produce strong to severe thunderstorms over CA and the Southwest. It is also worth mentioning that more snow will fall in elevated areas, further accentuating snowpack and hydrological resources over the West. While the western states tend to cool, locations east of the Rocky Mountains should undergo a warming trend by the middle of next week (southwest flow aloft).