146
FXUS01 KWBC 172013
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
410 PM EDT Thu Sep 17 2026

Valid 00Z Fri Sep 18 2026 - 00Z Sun Sep 20 2026

...Heavy rain and flash flooding threats shifting from the
southern Rockies tonight to across the north-central U.S. over the
next couple of days...

...Record-challenging high temperatures continue across the
South-Central U.S....

After a very active day of flash flooding across the Southwest and
Great Basin, the focus for heavy rainfall will shift toward the
southern Rockies this evening, and across the northern Plains to
the lower Great Lakes during the next couple of days. This is in
response to a relatively deep and slow-moving upper low moving
through the Intermountain West toward the Great Plains, spawning
low-pressure waves along a meandering front. WPC maintains a
slight risk of excessive rainfall for the southern Rockies through
this evening due to additional thunderstorm development in the
moisture-laden air mass. Meanwhile, a slight risk of excessive
rainfall is forecast to emerge across the northern Plains through
tonight. By Friday, the focus of excessive rainfall will shift
eastward across the upper Midwest, reaching the lower Great Lakes
on Saturday. For the East Coast, more widely scattered showers and
embedded thunderstorms can be expected from New England to the
Mid-Atlantic through tonight, shifting farther south into the
southern Mid-Atlantic Friday into Saturday. This is in response to
a Canadian high-pressure system pushing the front farther south
into the eastern U.S. over the next couple of days.

As we head deeper into September, cooler air from Canada is
beginning to dip further into the Northern Tier states, bringing
cooler-than-normal temperatures behind the aforementioned
low-pressure waves. Meanwhile, an upper-level high associated with
the persistent heat dome remains strong across the South,
resulting in a pronounced north-south temperature contrast. High
temperatures in the 60s to lower 70s can be expected north of the
meandering front across the northern tier states, compared to
upper 90s and triple-digit highs south of the front across the
Southern Plains and Mid/Lower Mississippi Valley. High
temperatures reaching the upper 90s to lower 100s will challenge
daily records from the Southern Plains to the lower Mississippi
Valley where Heat Advisories remain in effect. By this weekend,
the stronger push of cool Canadian air will begin to show signs of
breaking down the stubborn upper high. Meanwhile, remnant
instability associated with a stationary front on the southern
edge of the heat dome will continue to bring scattered
thunderstorms with some tropical heavy downpours across the
southern half of the Sunshine State. A marginal risk of excessive
rainfall is now in place across southern Florida including the
Keys through Saturday.


Kong/Asherman


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






$$