WEATHERAmerica Newsletter, SHORT RANGE OUTLOOK; Saturday, August 9, 2025

[Larry Cosgrove]

SHORT RANGE OUTLOOK

(Through The Next 72 Hours)

 

Another Heat Ridge Builds Across The Eastern Two-Thirds Of The Lower 48 States

METEOBLUE

PivotalWeather.Com (3)

ECMWF

There are a lot of complicated features across North America with respect to the general forecast. But a quick breakdown shows a Sonoran heat ridge, a weakness from Texas through the Great Plains and Mississippi Valley (linked to a strong trough and storm set to push across the Prairie Provinces) and a Bermuda High that may retrogress into the Southeast, forcing like westward motion of a subtropical disturbance/diffuse front toward the western/central Gulf Coast. There is some potential for a tropical depression or storm to take shape off of the New Jersey shore, and I cannot rule out the more southern system intensifying if there is some distance into the very warm water. It looks like the two ridges may conjoin at midweek, which would suppress diurnal convection above the Interstate 40 corridor and make the Lone Star State and Deep South at risk for nocturnal thunderstorm episodes as well.

Thunderstorm Chances On The Rise Midwest/Great Lakes, Intermountain Region And The Southeast

METEOBLUE

UQAM Meteocentre (3)

TwisterData.Com (3)

University Of Wisconsin Weather Server (3)

College Of DuPage Weather Laboratory

The long-lived negative 500MB height anomaly from the Aleutian Islands to the Gulf of Alaska is forecast to eject four strong impulses across southern Canada during the next ten days. Each disturbance and frontal structure will keep out hot air in the Prairie Provinces, while at the same time enable threats for severe weather. The greatest severe weather threats are in the Great Plains into the Great Lakes on Sunday and Monday, and also in the Southeast/Gulf Coast due to a retrogressive subtropical low. I also think the brief hot and dry period in the West will end this week as the monsoonal moisture kicks in. Instability and upward vertical motion signatures suggest a burst of intense rain and thunder coming into Arizona and New Mexico on Tuesday night and Wednesday.