Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Sat Sep 04 2021

Valid 12Z Sat Sep 04 2021 - 12Z Mon Sep 06 2021

...Organized thunderstorms expected to bring heavy rain and areas of flash
flooding today from the central Plains to the Mid-Mississippi Valley...

...Seasonally cool from the Central Plains to Northeast but hot and humid
across the southern Plains; increasingly hot throughout the West to
promote poor air quality and wildfires...

...Occasional showers and storms over Florida, spreading eastward into the
Northeast and Appalachians by Labor Day...

The weather pattern across the U.S. this Labor Day weekend will generally
be much less active than previous weeks.  Nevertheless, thunderstorms
across much of Kansas this morning could be quite strong as they generally
track eastward near a wavy frontal boundary.  Some of these storms will
contain heavy downpours which could lead to areas of flash flooding.  The
heaviest rains should then push further east into the mid-Mississippi
Valley by tonight while less vigorous showers and thunderstorms slowly
move southward across the central Plains.  The associated frontal system
will gradually merge with a larger low pressure system in central Canada. 
This will act to push the showers and thunderstorms more steadily eastward
across the Ohio Valley, Appalachians, and into the Northeast on Sunday.  
Some thunderstorms could reach the Mid-Atlantic on Labor Day but the best
chance of showers and some thunderstorms appear to be in Maine ahead of
the frontal triple-point.  Meanwhile, showers and thunderstorms will also
move more steadily southward across the southern Plains and parts of the
southern Rockies on Sunday and Monday near and ahead of the trailing cold
front.

Temperature-wise, summer heat and humidity will be found ahead of the
trailing front across the southern Plains and lower Mississippi Valley. 
Daytime highs both today and Sunday should reach the mid-upper 90s with
heat indices as high as 110 degrees.  The aforementioned cold front should
bring somewhat cooler conditions to Oklahoma and northern Arkansas by
Sunday, but south Texas and the rest of the Deep South look to remain
sultry.  Out West, temperatures will return to above normal levels up and
down the West Coast on Saturday and will only get hotter as Labor Weekend
progresses.  The Great Valley of California may see highs reaching the
century mark in spots by Sunday.  The coolest weather is set to be on the
north-side of the cold front in the central Plains where high temps will
struggle to get out of the 70s (roughly 10-15 degrees below normal).  The
Northeast looks to remain on the seasonally cool side each day this
weekend, but rising dew points will make a slightly more humid day on
Sunday.  Summer heat and humidity are anticipated in the Southeast with
the whole region (excluding Florida) having a good chance to be mostly dry
heading into Labor Day.

Elsewhere, a quasi-stationary front will linger near the northern Gulf
Coast and over central Florida. This means daily rounds of pop-up showers
and storms each afternoon, some of which could contains heavy downpours in
these areas. Farther west, unsettled weather is also on tap for parts of
the Southwest where atmospheric moisture content remains elevated.  Look
for scattered showers and storms to be a common occurrence in southern New
Mexico and into the Texas Panhandle this weekend. Lastly, Air Quality
Alerts remain in effect across parts of the Pacific Northwest and
California due to ongoing bouts with smoke from ongoing wildfires.

Kong/Mullinax