Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
221 AM EDT Tue Sep 22 2026

Valid 12Z Tue Sep 22 2026 - 12Z Thu Sep 24 2026

...Significant Heavy Rainfall/Flooding Threat across New Mexico and the
Southern High Plains through Wednesday...

...Heavy Rainfall/Flooding Threat across portions of the Ohio Valley,
Mid-Atlantic, and Southeast through Wednesday...

...Severe Thunderstorm Threat across portions of the Southeast through
Tuesday...

A upper-level low/trough will dig into the Southwest and interact with
both the Pacific and Gulf moisture, leading to showers and thunderstorms
across portions of the Four Corners, southern and central Plains/Rockies,
and the Great Basin. The combination of deep tropical moisture, sufficient
instability, and upper-level forcing will lead to high rainfall rates and
excessive rainfall across portions of the Four Corners and western Texas
on Tuesday. Additionally, WPC has issued a Moderate Risk (level 3/4) of
excessive rainfall for southern New Mexico, while a broader area of Slight
Risk (level 2/4) covers much of New Mexico. The flash flooding threat is
expected to increase on Wednesday, as the primary shortwave energy lifts
northward through New Mexico. Therefore, the Marginal and Slight Risk for
excessive rainfall will expand into central Plains, while a broad area of
Moderate Risk will encompass much of eastern New Mexico. The southwest
moisture will gradually transport northeastward along a slow-moving
boundary, bringing showers and thunderstorms across the northern/central
Plains into the Upper Midwest by late Wednesday into early Thursday.

Furthermore, a upper-level troughing over the Great Lakes will gradually
shift eastward toward the Mid-Atlantic and Northeast, while the frontal
boundary will settle southward across the southern Plains into the
Southeast, Ohio Valley, and Mid-Atlantic. A developing coastal low
offshore will help maintain low-level moisture ahead of the slow-moving
frontal boundary, supporting period of showers and thunderstorms from
portions of the Ohio Valley/Mid-Atlantic into the Appalachians and
Southeast. Pockets of elevated instability may develop along the frontal
boundary, leading to severe thunderstorm concerns across the Southeast.
Additionally, slow storm motions and efficient warm moisture will lead to
locally high rainfall rates within the strongest storms, leading to flash
flooding concerns over portions of the Ohio Valley/Mid-Atlantic and
Southeast.

By Wednesday, the boundary over the Mid-Atlantic and Ohio Valley will move
further south, but shortwave troughs will reinforce another round of
showers and thunderstorms across the area. This will lead to another day
of flash flooding concerns over the Mid-Atlantic and Ohio Valley,
especially over areas where soil remains saturated from previous rainfall.
Further south, a moist and unstable airmass will persist across southern
Florida leading to scattered to numerous showers and thunderstorms, with
locally heavy downpours possible through Thursday.

Temperature-wise, a strong surface high will bring colder than average
temperatures across the northern/central Plains into the Mid-Atlantic and
Northeast behind the frontal boundary, while the southern Plains into the
Southeast will remain warm and humid.

Oudit


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

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