WEATHERAmerica Newsletter, Sunday, September 7, 2025; SHORT RANGE OUTLOOK

[Larry Cosgrove]

SHORT RANGE OUTLOOK

(Through The Next 72 Hours)

 

Polar Air Mass Covers Much Of The Eastern Two-Thirds Of The Lower 48 States

METEOBLUE

PivotalWeather.Com (3)

ECMWF

I need to clarify the character of the air mass covering the central and eastern portions of North America. Although rather chilly in terms of night temperatures, and certainly quite anomalous for occurring in late summer, this is a polar air mass (cPk) and not Arctic (cA). A designation of Arctic values implies subfreezing through 24 hours a day within the confines of the air mass, and so far readings have gone below 32 deg F only at night and in a relatively small area. That said, this refreshing regime has brought out the jackets and light overcoats as far south as the Ozark Plateau. The hotter air has been displaced below Interstate 10. The cold core can be designated a vortex (<534dcm at 500MB), but will not linger at a lower latitude (James Bay at furthest south position). All things considered, this early introduction of air from northern  Canada will wipe out cooling demand across a wide portion of the lower 48 states in the near term.

Rain, Thunder From Monsoon, Lorena Moisture Fetch Impacts The West And Texas

METEOBLUE

University Of Wisconsin Weather Server (3)

TwisterData.Com (3)

UQAM Meteocentre (3)

College Of DuPage Weather Laboratory

There is still a lingering monsoonal moisture fetch across the western half of the U.S., which was accented by the surge of dewpoints from what once was Hurricane Lorena. The presence of rain from diurnal + orographic convection will curtail eastward expansion of the hot air across the Desert and Intermountain Region. The core surge of the former tropical cyclone may generate an MCC or MCS across central and/or southern Texas late Sunday into Monday morning. If a thunderstorm group does develop, interaction with the front could create widespread and intense rains along the Interstate 10 corridor. There could be chances for heavy rain in spots along the shoreline of the Gulf of Mexico and the Atlantic Ocean as the frontal structure slows. Ultimately, Florida could see relentless rain and thunder for the entire near term.