WEATHERAmerica Newsletter; Sunday, September 7, 2025; MEDIUM RANGE OUTLOOK

[Larry Cosgrove]

MEDIUM RANGE OUTLOOK

(Four To Ten Days From Now)

 

We Gradually Lose The Colder Air In The East....

UQAM Meteocentre (4)

TwisterData.Com (4)

TrueWx.Com (4)

College Of DuPage Weather Laboratory

We are a long way from maintaining cold air profiles, since ground saturation of heat and still lengthy periods of daylight will act to reverse cold intrusions. Lack of any snow cover is another reason that you should not be thinking of winter just yet. The heavy rain bands along the East Coast may culminate in a subtropical low, which might keep the cool and rain going along the Interstate 95 corridor for a while longer. Mostly, however, risks for heavier convection will regroup through southern Canada. The polar regime willo move north of the border, and likely stay put for a while.

....While Heat Builds Through The Great Plains And Dixie

ECMWF (4)

PivotalWeather.Com (4)

The character of the medium range may get in one last "hot shot" before chances for summer weather are gone for good. A deep upper low will settle over Ontario, and start the process of building an elongated 500MB trough and gyre across central and eastern Canada. Another trough in the West will keep a lid on extreme heat through the Intermountain Region. But cT and mT air masses will regroup in the Desert Southwest and in an area from the High Plains across the Old South into the Eastern Seaboard. There could be some potential for a tropical system along the Gulf Coast or Southeast shoreline, but the greatest weather threat will be in the West and Great Lakes due to strong thunderstorm potential.