MEDIUM RANGE OUTLOOK
(Four To Ten Days From Now)
Warm, Humid Pattern Through Much Of The Lower 48 States….
For those of you reading this report in the south central USA, rest assured that the coming hotter air mass will not be of the dangerous variety seen more than a week ago. Rather, this is merely “annoying”, a rise in temperature over the seasonal normals that mostly will range in the mid/upper 90s, not the brutal 105-110 deg displays that characterized the Sonoran heat ridge. Some of the warmer, more humid values will move further north, escorted by upper disturbance and weak surface fronts.
But note the exceptions in this forecast. Cooler air will accompany a 500MB closed low moving into the Pacific Northwest. And a diffuse front may give rise to a subtropical low in Georgia and Florida by next weekend. That system could lay down some serious rain and thunder if its surface reflection deepens as the GFS model suggests, spreading heavy precipitation as far north as New England before breaking up on September 26.
….But That Mexican Bubble Heat Ridge Will Control Texas For A While Longer!
UQAM Meteocentre (4)
College Of DuPage Weather Laboratory
Whereas thunderstorms may provide an escape to heat in the Great Plains above Texas, and along the Eastern Seaboard, the Mexican bubble ridge complex should prove very persistent into the longer term forecast. The northern edge of this subtropical high should bring its hotter air into the Interstate 40 corridor from S CA into OK, with NM, TX and LA getting the “last chance to rise near 100 deg F” before the lowering sun angle drops the century mark readings close to the 500MB core in Mexico.