Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
950 FXUS01 KWBC 071928 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 327 PM EDT Mon Sep 07 2026 Valid 00Z Tue Sep 08 2026 - 00Z Thu Sep 10 2026 ...Severe thunderstorms and heavy rainfall expected across the Northern Rockies and the Northern Plains today, spreading southeastward this week... ...Modest relief from the heat across the midsection of the country late Wednesday; cooler air begins to moderate across the Northeast and Western U.S.... ...Scattered thunderstorms linger across the Southeast... As a large high-pressure system brings fine and cool weather across the Great Lakes and the Northeast this Labor Day, a low-pressure system is spreading unsettled weather into the northern Rockies and the northern Plains. This is in response to a deep upper-level low getting ready to eject out of the northern Rockies toward southern Canada. Strong dynamics associated with this weather system will bring heavy rainfall and scattered severe thunderstorms across the Northern Rockies to the Northern Plains as today progresses. The low-pressure system is forecast to intensify and move into the southern prairies of Canada by tonight, but the potent cold front trailing from the low center will bring a round of strong to severe thunderstorms as the front sweeps through the northern Plains today, reaching into the upper Midwest tonight. By Tuesday, the southern portion of the front will lose some momentum, allowing showers and thunderstorms to develop over the north-central Plains and advance gradually into the Upper Midwest by Wednesday morning. A Slight Risk of excessive rainfall remains in effect across Iowa Tuesday to early Wednesday. As the high pressure system continues to expand southward into the Eastern U.S. and encounters the heat dome anchored over the country`s midsection, the frontal boundary will eventually stall before reaching the Gulf Coast. This pattern will allow scattered thunderstorms to linger across the Southeast, including the Sunshine State, through the next few days. Behind the front, much of the Northeast and Mid-Atlantic will begin a gradual warming trend towards more seasonable temperatures as the cool airmass begins to moderate, with the exception of northern Maine as reinforcing cold air arrives Wednesday morning. Temperatures across the Western U.S. will follow a similar warming trend beginning tomorrow as mid-level heights rise with the departure of the lingering upper-low. East of the Rockies, some much needed relief from the oppressive heat is expected late Wednesday with the arrival of the trailing cold front from the Canadian cyclone. Until then, however, daytime highs in the upper-90s and triple digits combined with record warm temperatures will maintain dangerous heat for the next 24-48 hours over the Plains and Middle Mississippi Valley. Asherman/Kong Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php Extreme Heat Key Messages available at: https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_1.png $$