Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
334 PM EDT Fri Aug 25 2023

Valid 00Z Sat Aug 26 2023 - 00Z Mon Aug 28 2023

...Dangerous heat continues from the Midwest to Gulf Coast, with heat
relief expected to begin this weekend...

...Excessive Rainfall leading to Flash Flooding possible across portions
of the Western High Plains today...

Widespread heat across much of the central U.S. is set to slowly diminish
in intensity and coverage this weekend as the upper-level ridge
responsible for this heat wave weakens and retreats toward the west.
However, potentially record-breaking high temperatures of 90 to 100F+ are
expected across much of the central and southern U.S. today, with high
humidity accompanying this heat. The combination of high heat and humidity
will result in heat indices of 100 to 110+F, with some spots approaching
heat indices of 120F. Additionally, widespread record warm low
temperatures are expected across the much of the central and eastern U.S.,
limiting nighttime heat relief. Do not underestimate the potential for
heat-related illness - have a way to break your heat exposure, cool down,
and stay hydrated. As the upper-level ridge responsible for the heat
gradually weakens, a cold front will slowly progress southeastward through
the region, ushering in a much cooler airmass. By Sunday morning, the cold
front will have progressed through much of the central U.S., concentrating
the heat toward the southern U.S. and Gulf Coast. High temperatures over
the central U.S. will be 15 to 25 degrees cooler than Friday's highs by
Sunday afternoon. Areas over the Southeast and along the Gulf Coast will
continue to be hot through this weekend, but heat relief is finally
expected to arrive by early next week.

Widespread scattered shower and thunderstorm activity is possible across
portions of the Western High Plains through Saturday morning as a result
of shortwave energy (associated with the remnants of Harold) moving
through the region. This upper-level energy in addition to anomalously
high moisture content will be able to generate thunderstorms producing
rain rates of 1"/hr, with isolated totals of 1-2" in the forecast.
Scattered instances of flash flooding will be possible, particularly in
urban areas and over burn scars. Therefore, a Slight Risk of Excessive
Rainfall is in effect through Saturday morning across portions of eastern
Colorado, southeastern Wyoming, as well as the adjacent portions of Kansas
and Nebraska. On Saturday and Sunday, the upper-level energy will move
toward the east, resulting in summertime thunderstorm activity across the
Southwest. Marginal Risks for Excessive Rainfall are in effect over the
Southwest on Saturday and Sunday associated with these summertime
thunderstorms. Over the eastern half of the country, isolated to scattered
thunderstorms will be possible as the aforementioned cold front progresses
through the eastern half of the country. Marginal Risks for Excessive
Rainfall are in effect along scattered portions of this frontal boundary,
particularly over the south-central Plains as well as the Tennessee
Valley/Mid-Atlantic.

Elsewhere across the country, heat is expected to briefly intensify across
the Pacific Northwest this weekend as the upper-level ridge currently in
place over the central U.S. retrogrades toward the west. However, this
heat will be less intense than the heat the region has recently seen, and
is not expected to last long. A cold front is set to enter the region by
early next week, which will cool temperatures down significantly.


Genz

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