647
FXUS01 KWBC 170738
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
338 AM EDT Sun Aug 17 2025

Valid 12Z Sun Aug 17 2025 - 12Z Tue Aug 19 2025

...Rounds of thunderstorms with a heavy rainfall and flash flood
threat for the Upper Midwest through Monday...

...Scattered thunderstorms expected across portions of the
Northeast/Carolinas, Florida/Gulf Coast, and Southwest the next
couple of days will bring an isolated threat of flash flooding...

...Hazardous heat builds across parts of the Plains, Midwest, and
Mid/Lower Mississippi Valley through early next week...

An upper-level shortwave and accompanying slow moving surface
frontal system will trigger rounds of thunderstorms across much of
the Upper Midwest Sunday-Monday. Plentiful moisture/instability
will promote heavy downpours with organized clusters of
thunderstorms contributing to long-duration rainfall and heavy
totals. There is a Slight Risk of Excessive Rainfall (level 2/4)
covering portions of the eastern Dakotas, central/southern
Minnesota, and western Wisconsin where scattered to potentially
numerous instances of flash flooding can be expected. As the
system progresses eastward Monday another Slight Risk is in effect
centered on portions of southern Wisconsin/far northern Illinois
for additional scattered instances of flash flooding. Scattered to
widespread thunderstorms are also expected across much of the
eastern U.S. To the north, storms along and ahead of a cold front
pushing through the Northeast/Ohio Valley on Sunday and into the
Carolinas/southern Appalachians Monday may lead to some isolated
instances of flash flooding. Additional storms are forecast across
the Florida Peninsula and westward along the central Gulf Coast
the next couple of days, with a greater risk for heavier
rainfall/isolated flash flooding on Sunday. Further west, more
scattered to isolated thunderstorms are forecast over the Plains
and into the Southwest through Monday. However, plentiful moisture
will bring the threat for brief but potentially heavy downpours
particularly over portions of the southern High Plains into the
Southwest, with isolated flash flooding possible. Elsewhere,
periodic upper-level waves and a lingering frontal boundary will
help to trigger scattered thunderstorms across the northern Great
Basin and into the northern Rockies on Sunday. While heavy
rainfall/winds are expected to remain well offshore the East Coast
as Hurricane Erin passes by to the east this upcoming week,
life-threatening surf and rip currents are expected and will begin
possibly as early as Monday.

Conditions will remain very hot and muggy over portions of the
eastern Plains, Midwest, and Middle/Lower Mississippi Valley to
end the weekend and through early next week. Heat Advisories cover
much of the region as afternoon heat indices willl climb into the
105-110 degree range. In addition, lows in the mid- to upper 70s
will bring little relief from the heat overnight. While not quite
as intense, another hot and humid day is in store for much of the
Northeast Sunday as highs climb into the low 90s. However, a cold
front will bring relief on Monday as highs fall into the 70s for
most locations. Forecast highs will also remain Summer-time hot
and into the 90s across the Southeast, Gulf Coast, and northward
through the Plains Sunday-Monday. A growing upper-level ridge will
bring hotter temperatures to the Intermountain West as well with
highs generally in the 80s on Sunday rising into the 90s Monday.
Meanwhile, portions of the Upper Midwest/Great Lakes north of a
frontal boundary will remain unseasonably cool, with highs in the
60s and 70s. The West Coast will also remain below average
Sunday-Monday, with 60s and 70s expected.

Putnam


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