Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
338 PM EDT Sun Sep 03 2023

Valid 00Z Mon Sep 04 2023 - 00Z Wed Sep 06 2023

...Showers and storms continue across the Intermountain West today and
into Monday with a Slight Risk for Flash Flooding...

...Unseasonably hot conditions continue for much of the central and
eastern U.S., with record-tying/breaking temperatures possible...

A stagnant upper-level low that has been anchored over the West this
weekend will begin to move eastward the next couple of days with
associated shower and thunderstorm chances shifting from the Intermountain
West into the High Plains. Very anomalously high surface moisture
lingering in the region will lead to some locally heavy downpours. A
Slight Risk of Excessive Rainfall (level 2/4) remains in place for
portions of the northern Great Basin and Northern Rockies Sunday
afternoon/evening for the risk of some scattered instances of flash
flooding, particularly for more sensitive regions such as burn scars, dry
washes, and urban areas. The threat shifts eastward deeper into the
Northern Rockies and adjacent High Plains on Monday, with another Slight
Risk of Excessive Rainfall in place. Conditions should clear out late
Monday into Tuesday. High temperatures will continue to be unseasonably
cool across the West under the influence of the upper-level low and
widespread clouds/precipitation. Forecast highs Monday are mainly in the
60s and 70s for the Pacific Northwest, Northern Rockies, Great Basin, and
coastal California, with 80s for the central California Valleys and 90s
for the Desert Southwest. Temperatures look to rise 5-10 degrees on
Tuesday as the upper-level low moves eastward out of the region and
conditions moderate.  

To the east, high temperatures will continue to be unseasonably hot for
much of the central and eastern U.S. as a broad upper-level ridge remains
in place. In what has already been a brutally hot Summer, highs will once
again be in the upper 90s to low 100s for Texas and the Southern Plains.
Highs will also be into the mid-90s to low 100s for the Central Plains,
with low 90s forecast for the Great Lakes Region. Much of the focus will
still be on portions of the Northern Plains/Upper Midwest where the
greatest temperature anomalies have resided. Highs will be into the upper
90s on Monday, with many record-tying/breaking highs possible. Heat of
this magnitude this time of year will pose a higher than normal health
risk, especially for those who might be outdoors for the Holiday and
without adequate cooling available. Low temperatures will also be
unseasonably warm by as much as 20-30 degrees, with many locations
remaining in the 70s overnight. However, significant relief will come for
much of the region later Monday and into Tuesday as the upper-wave over
the West pushes east and helps to drive a pair of frontal systems into the
region. Areas where the front has already passed through by Tuesday
morning from eastern Montana into the western Dakotas will mainly be in
the 60s. Shower and storm chances along the front will also help to keep
temperatures down more broadly from the Upper Midwest southwest into the
Central High Plains on Tuesday. 

The hot weather has also made a return to the East Coast. Highs Monday and
Tuesday will range from the mid-80s in New England to the upper 80s and
low 90s in the northern Mid-Atlantic and mid- to upper 90s in the southern
Mid-Atlantic and Carolinas. Many near record-tying/breaking highs are
forecast for this region as well. Elsewhere, a weak upper-level wave and
lingering frontal boundary will keep thunderstorm chances in the forecast
for the Lower Mississippi Valley. Temperatures more broadly across the
region from the Lower Mississippi Valley east into the Ohio Valley, the
Southeast, and Florida will be hot but more seasonable compared to other
central/eastern U.S. locations, with highs in the upper 80s and low 90s. 

Putnam


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php