WEATHERAmerica Newsletter; Saturday, August 2, 2025; MEDIUM RANGE OUTLOOK

[Larry Cosgrove]

MEDIUM RANGE OUTLOOK

(Four To Ten Days From Now)

 

That Was Quick! Hot Weather Rapidly Expands Across Lower 48 States....

ECMWF (4)

PivotalWeather.Com (4)

While the cool regime across the eastern 2/3 of the lower 48 states is impressive for its depth and geographic coverage, the string stored heat and still-high August sun will work to eradicate the polar air mass. Warmth will build from Mexico into Texas and the Great Plains, and by next weekend cover nearly all of the USA as the monsoonal fetch merges with a shortwave in the Pacific Northwest. Initially, the heating will be dry, with lower dewpoints at the middle levels. But moisture will creep into the anticyclone across most of Dixie, the Ohio Valley and Mid-Atlantic states as the heat ridge assumes a dirty character.

....As A New Cold Pool Builds Across Canada

UQAM Meteocentre (4)

TwisterData.Com (4)

TrueWx.Com (4)

College Of DuPage Weather Laboratory

If you were to look at the Canadian weather composite for the medium range, you would see a vastly different profile from that of the lower 48 states. The current Aleutian/Gulf of Alaska Low complex will continue to eject shortwaves, with surface frontal structures that grab heat and humidity south of the border. This is a recipe for multiple cases of thunderstorms and cooler air from British Columbia into the northern halves of Ontario and Quebec (southern portions of those provinces will, for a while at least, be chiefly influenced by the Sonoran + Bermudan heat ridge system). This is the time of year where severe weather in Canada is most common, with hail and isolated tornado threats appearing in the Prairie Provinces. Late in the month, south and east advancement of convection from the Lake Of The Woods and James Bay may threaten the Great Lakes and the Northeast U.S.