WEATHERAmerica Newsletter; Saturday, June 28, 2025; MEDIUM RANGE OUTLOOK

[Larry Cosgrove]

MEDIUM RANGE OUTLOOK

(Four To Ten Days From Now)

 

Sonoran + Bermudan = Excessive Heat Over A Wide Area Of The USA....

ECMWF (4)  

Pivotal Weather.Com (4)

The upper air pattern shown here is almost like a La Nina climatology textbook. A weakness or 500MB trough along the West Coast, a cold closed low in Atlantic Canada, with a semizonal polar jet stream between the two negative height anomalies. Heat ridges pop up in the Sonoran and Bermudan positions, occasionally linked but sometimes with a discontinuity present. The nature of the conjoined ridge complex is often dirty, with pockets of haze and convection amongst the searing heat and awfully high surface humidity. Canada will see changeable readings, but likely stormy conditions as impulses race along or just above the International Border. The ECMWF version weeklies have drawn a bad on Texas and the Ohio Valley/Mid-Atlantic having the hottest conditions, with monsoonal moisture affecting the Desert and Intermountain Region via orographic and diurnal thunderstorm formation.

....Which May Continue For A (Long) While! Provided The Tropics Do Not Get In The Way....

UQAM Meteocentre (4)

TwisterData.Com (4)

TrueWx.Com (4)

College Of DuPage Weather Laboratory

Now that the tropics seem to be more of a factor in the forecast, hot temperature outlines may be vulnerable to a disturbance or declared storm. For instance, the GFS version makes a big deal out of the wave over the Greater Antilles, making the system a minimal hurricane that targets New Orleans LA in about nine days. That prediction may be overdone; but it is worth mentioning that many of the other forecast schemes have a disturbance in either the western Atlantic Ocean or the Gulf of Mexico. Monsoonal moisture from Mexico will reach the Desert and Intermountain Regions, though probably not in great enough quantity to allow for any cooler temperatures (that should happen in the third week of July, however). I suspect that there will be no major changes in the temperature alignment outside of maybe the immediate Pacific shoreline and New England through the middle of the new month.