Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
353 AM EDT Thu Aug 24 2023

Valid 12Z Thu Aug 24 2023 - 12Z Sat Aug 26 2023

...Dangerous heat continues from the Midwest to Gulf Coast, with relief
finally on the way for some by this weekend...

...Severe thunderstorms and flash flooding possible across the Lower Great
Lakes and parts of the central Appalachians into tonight...

...Scattered flash flooding concerns forecast from the central Great Basin
to the central High Plains through Friday...

Yet another day of dangerous and oppressive heat is anticipated throughout
a large portion of the Nation situated underneath a potent upper level
ridge. Record-breaking heat with forecast highs into the upper 90s and low
100s will impact a broad region between the Midwest and central Gulf Coast
today. When factoring in sultry humidity levels, heat indices could
approach 120 degrees. This heat wave will pose a greater health risk than
usual, and be potentially deadly, due to multiple consecutive days of
extreme heat, the intensity of the heat, and lack of overnight cooling
associated with record warm overnight lows. Heat Alerts (Excessive Heat
Warnings/Watches and Advisories) currently span across 20 states and
include just over 110 million people. Residents are advised to follow
proper heat safety by staying hydrated, avoiding extending periods of time
outdoors, and looking out for vulnerable family members, friends, and
neighbors. The good news for northern regions impacted by ongoing
sweltering conditions is that a cold front will begin to push south today
and bring much more comfortable temperatures to much of the Midwest by
Saturday. However, searing heat will remain throughout the South into the
start of the weekend.

On the northeast periphery of the aforementioned upper ridge, shower and
thunderstorm chances exist from parts of the Lower Great Lakes to the
Upper Ohio Valley and Northeast. A slow-moving warm front will provide a
focus for developing thunderstorms. These storms will be able to take
advantage of elevated atmospheric moisture content to create intense
downpours. As a result, the threat of flash flooding exists from northeast
Ohio to much of Pennsylvania and southern New York State. Thunderstorms
may also contain damaging winds, large hail, and perhaps and tornado
between southern Michigan to western Pennsylvania. By Friday, the frontal
system is expected to push farther south and east, spreading
rain/thunderstorm chances to New England and the Mid-Atlantic.

Farther west, remnant tropical moisture from Harold rounding the western
edge of the central U.S. upper ridge will continue to lead to scattered
flash flooding potential over the central Great Basin today. In
particular, southern Utah and western Colorado are located within a Slight
Risk (level 2/4) of Excessive Rainfall. These areas are situated within
overlapping vulnerable terrain and best atmospheric conditions conducive
for heavy rainfall. The flash flooding risk is expected to shift into the
central Rockies and central High Plains by Friday as the aforementioned
lingering tropical moisture interacts with an approaching cold front. A
few inches of rain within a short period of time could lead to rapid
runoff and flooding concerns.

Snell

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