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

Valid 12Z Thu Sep 17 2026 - 12Z Sat Sep 19 2026

...Additional flash flooding expected over sections of the Southwest,
Northern Plains, and Upper Midwest over the next three 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 is expected to shift towards the
Southern Rockies ahead of a moisture-laden disturbance acting to enhance
showers and thunderstorms. While the overall coverage of storms will be
lower than yesterday, any flash flooding could be similarly impactful as
high rainfall rates continue amid the anomalous moisture in place. The
same Southern Rockies disturbance will eventually trigger the formation of
a new low-pressure system over the central High Plains tonight. As this
system consolidates in the overnight hours, a developing axis of heavy
rainfall along the front will support the threat of widely scattered flash
flooding from the Northern Plains to the Upper Midwest tomorrow and
Saturday.

As we get into mid-September, cooler air from Canada is beginning to dip
into the Northern Tier states, bringing cooler than normal temperatures
behind the aforementioned low-pressure area. 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 low 70s and upper 60s can be expected north of the
meandering front in the Central Plains and Midwest, compared to upper 90s
and triple-digit highs south of the front across the Southern Plains and
Mid/Lower Mississippi Valley. Unfortunately, the western end of the front
lifting northward means that the hazardous heat is here to stay this week
across the South. In fact, high temperatures reaching into 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.
Meanwhile, instability associated with a stationary front on the southern
edge of the heat dome will continue to bring scattered thunderstorms with
heavy downpours across much of the Sunshine State, although excessive
rainfall is not expected from this activity.

Asherman/Kong


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

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