WEATHERAmerica Newsletter, Saturday, March 1, 2025; SHORT RANGE OUTLOOK

[Larry Cosgrove]

SHORT RANGE OUTLOOK

(Through The Next 72 Hours)

 

A Cold East, Warm West Alignment To Start....

METEOBLUE

PivotalWeather.Com (3)

ECMWF

Seems eerily quiet, right? Indeed, colder air is mostly over the Great Lakes and Northeast, and an almost beatific sky and temperature array is in place elsewhere in the nation. The precipitation chances increase on Sunday as the first in a series of storms and frontal structures approach from the eastern Pacific Ocean. Southwest flow will elevate temperatures to the right of the Rocky Mountains. Much colder air in central and eastern Canada should not get into the lower 48 states, associated with a separate cA vortex taking shape near Hudson Bay. But all of this pleasantry will be interrupted early next week, sweeping eastward from the Intermountain Region into the Great Plains/Mississippi Valley.

....And A Potentially Dangerous Severe Weather Outbreak To Finish!

METEOBLUE

UQAM Meteocentre (3)

University Of Wisconsin Weather Server (3)

TwisterData.Com (3)

College Of DuPage Weather Laboratory (2)

I will not kid you. This atmospheric scenario is almost a sure bet for a synoptic-scale severe weather outbreak in places over the eastern half of the lower 48 states. Instability should not be a problem (due to some of the predictive schemes having not initialized the moisture fetch very well, a common problem with synoptic-scale cyclones previous to 48 hours before occurrence). The sharpness of the 500MB trough, its core of vorticity, difluent structure and well-defined triple point convergence at surface (cP/cT/mT) all spell trouble with a textbook-case convective threat. If the low center drops below 990MB and heads west of the Appalachian Mountains, then intense convection will develop along or just west of the Interstate 35 corridor below Wichita KS around 12N on Tuesday, March 4, and not leave the U.S. East Coast until early morning Thursday March 6. There is some risk of an MCS in the "Arklatex" vicinity into the lower Mississippi Valley, but as of now the upper vertical velocities are pointing toward mainly discrete supercells.

The linear projection of the upper disturbance argues against much of a snow threat, although frozen precipitation could appear in the northwest quadrant of the storm complex from northern Kansas into the "Soo Locks" vicinity and St. Lawrence Valley. But I will emphasize that the risks are mainly with the warm sector convection and associated heavy rain/severe weather.