WEATHERAmerica Newsletter, Saturday, July 23, 2022 at 10:45 P.M. CT; Medium Range Discussion

[Larry Cosgrove]

MEDIUM RANGE OUTLOOK

(Four To Ten Days From Now)

Cool Canada Vs. Hot U.S. Scenario Emerges....

ECMWF (4)

PivotalWeather.Com (4)

In a relative sense, we have a cool/mild Canada vs. a warm/hot U.S. alignment developing which may hold through the first two weeks of August. Occasionally the polar air mass, on the heels of a stronger cold low aloft, will reach into the Great Lakes and Northeast in the medium range. But I caution that the GFS model prediction for suppression of heat in the Great Plains and the Dixie states is probably overdone (a common bias of the series). The powerful subtropical high may bulge out into the Prairie Provinces and north central states: I seriously doubt that the cP regime gets into Oklahoma and Arkansas, although convection associated with the frontal structure may reach as far south as the Red River (TX/OK).

Weakening Polar Air Mass May Lower Temperatures In Northern Half Of U.S.

UQAM Meteocentre (4)

TrueWx.Com (4)

Weathernerds.Org (4)

College Of Dupage Weather Laboratory

The trend toward extreme heat and dryness along the West Coast and in Texas must be watched, since fire hazards are probable due to lack of rain and torrid weather. Notice that some of the numerical models are setting up a general thunderstorm boundary from Oklahoma into West Virginia between July 29 and August 2. I have some concerns that the boundary is too far south, especially since there is strong evidence for another shortwave to enter western Canada by the end of this time frame. Deviation of some of the monsoonal moisture fetch may permit convection to fire in the High Plains from Colorado into Montana. But I want to point out that the south central U.S. should not see any appreciable rainfall in this pattern, and indeed may continue well into next month with searing heat and aridity.