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

Valid 00Z Fri Aug 25 2023 - 00Z Sun Aug 27 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...

Dangerous and oppressive heat will continue 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 through Friday.
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 the 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 a large portion of the country. By this
weekend, a cold front moving southward should bring an end to the
excessive heat and some welcomed more comfortable temperatures to much of
the Midwest. Unfortunately though, excessive heat looks to continue across
portions of the southern Plains to the Gulf Coast well into next week. See
key messages from WPC for additional information about the ongoing heat.

On the northern side of the aforementioned upper ridge, showers and
thunderstorms will focus along a frontal boundary from parts of the Lower
Great Lakes to the upper Ohio Valley and Northeast this evening/tonight.
With ample moisture and instability present, flash flooding will be
possible from northeast Ohio to western Pennsylvania where WPC highlights
a slight risk (level 2/4) on the Excessive Rainfall Outlook for this
afternoon/tonight. Severe thunderstorms are also possible with the threat
for damaging winds, large hail, and perhaps a tornado. The Storm
Prediction Center has an enhanced risk (level 3/5) from southern Michigan
to far western Pennsylvania. On 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, monsoonal moisture 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 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.
Showers and storms should focus along the cold front as it drops farther
into the central Plains/Midwest on Saturday.

Santorelli/Snell

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