WEATHERAmerica Newsletter, SHORT RANGE OUTLOOK, Saturday, July 26, 2025

[Larry Cosgrove]

SHORT RANGE OUTLOOK

(Through The Next 72 Hours)

 

Broad Heat Ridge In Control Over Much Of Lower 48 States

METEOBLUE

PivotalWeather.Com (3)

ECMWF

If you use the 588dcm contour at 500MB, you can determine the expanse of the heat ridge in North America. Coverage of this positive height anomaly (and please do not term it as a "Heat Dome"...) will remain through most of this coming week. Cooler air may reach as low as Interstate 80 by Wednesday. But for the most part, this is a hot, humid pattern with a dirty ridge, which will ingest the Saharan Air Layer to go along with an incredible display of heat indices and stagnant air.

Monsoon Pulses Into The West And A Weakness Returns To Central Gulf Coast

METEOBLUE

UQAM Meteocentre (3)

TwisterData.Com (3)

University Of Wisconsin Weather (3)

College Of DuPage Weather Laboratory

Two separate entities in the synoptic scale discussion of weather across North America may expand influence over the next four to five days. The capacity for a 500MB weakness to develop over the central Gulf Coast may provide continued support for moisture advection into the middle of the USA, this despite a very persistent heat ridge signature that should still be holding off any major cP intrusion form Canada until perhaps Tuesday. Another aspect to monitor is the possibility that a disturbance now entering the Caribbean Sea could survive shearing wind profiles and hot/dry/dusty air injection from the Bermuda High. That might favor the ECMWF scheme scenario of a "rain bomb" across Louisiana next weekend.

The other issue is the summer monsoon. Combined with a cold upper trough in California and Oregon, the monsoonal moisture fetch has helped to produce astonishing snow and hail production in the High Sierra and some of the higher elevations in California, Nevada, and Arizona. The trough over the West may also funnel moisture into the complex frontal structure across the north central states , Great Lakes and Midwest. Very unstable values may collect ahead of the front and a mesolow, so dangers for flooding rains and severe thunderstorms will be fairly high as the cooler values try, usually without much success, to push out the heat and humidity associated with the subtropical high.