WEATHERAmerica Newsletter, Saturday, June 27, 2025; SHORT RANGE OUTLOOK

[Larry Cosgrove]

SHORT RANGE OUTLOOK

(Through The Next 72 Hours)

 

The Heat Stays Away From The Northern Tier States....

METEOBLUE

UQAM Meteocentre (3)

TwisterData.Com (3)

University of Wisconsin Weather Server (3)

College Of DuPage Weather Laboratory

It is not the potential for some cold air mass sweeping out of Canada that may keep the heat down above Interstate 70 in the USA. Rather, it is a series of weak/moderate cold fronts, generating intense thunderstorms, that will bring several  doses of modified mP and cP air masses with each passage. The heat ridge complex that brought an intense coverage of hot and humid air to the Midwest and Northeast has broken down. But note that a smaller version of the Sonoran subtropical high, and its counterpart Bermuda High in the western Atlantic Basin, will increase in size and intensity in the near term. Diurnal convection may occur in the Southeast (weakness at 500MB) and some of the Mexican monsoonal moisture fetch (aided by what is now TD 2) should bring thunderstorms into the Rio Grande Valley and the Desert Regions. But watch for temperature rises in the middle of the country and along the Gulf Coast, which will herald the start of another long-lasting heatwave.

....But Rebuilds Across Southern 2/3 Of The Lower 48

METEOBLUE

PivotalWeather.Com (3)

ECMWF

The 500MB configuration that is evolving is close to La Nina climatology. A trough or weakness along the West Coast; Gulf of Alaska formation with storm ejections across southern Canada into the Northeast; and tendency for a conjoined Sonoran and Bermudan heat ridge complex all favor some extreme heat that starts in the Desert Regions, migrates to Mississippi Valley, and then initiates record heat along the Eastern Seaboard below Portland ME. This will be a tough sequence to emerge from, as most model guidance shows a brutal course of hot weather in the lower 48 states in July. Texas and the ERCOT districts may be very near or just toi the left of the 500MB cores of 597dcm. It will be hot for a while!