336 FXUS01 KWBC 281924 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 323 PM EDT Mon Sep 28 2026 Valid 00Z Tue Sep 29 2026 - 00Z Thu Oct 01 2026 ...Potentially life-threatening flash flooding expected from the Southwest into the southern High Plains into early Wednesday... ...Significant flash flooding threat shifts into north-central Texas Wednesday, with heavy rain and river flooding concerns spreading into the central Plains and Upper Midwest... ...Dangerous heat continues in South Texas, and much of the East turns unseasonably warm... A multi-day and potentially dangerous flash flood event is getting underway across the Southwest as a strong upper-level low moves inland from California, crossing Arizona on Tuesday before reaching New Mexico by Wednesday. Ahead of this system, tropical moisture from the remnants of Hurricane Polo, which is forecast to move across Baja California tonight and into northwest Mexico on Tuesday, will be drawn northeastward into the region. Moisture levels this high are rare this late in the season. Combined with robust lift from the upper low, they will support torrential rainfall rates and repeated rounds of storms over the same areas. Moderate Risks of excessive rainfall (level 3 of 4) are in effect from Arizona and southern Utah into New Mexico, far west Texas, and the southern High Plains, and Flash Flood Watches cover much of the region. Numerous instances of flash flooding are expected, and some could become life-threatening, particularly Tuesday into Tuesday night when the heaviest rain is likely to fall after dark. Burn scars, urban areas, and normally dry washes will be especially vulnerable. A few severe thunderstorms with damaging winds are also possible Tuesday across the southern High Plains. Temperatures across the Desert Southwest will run well below average under the clouds and rain. By Wednesday, the moisture plume will surge northeastward along a slow-moving front from the southern High Plains to the Upper Midwest. North-central Texas is a particular concern. repeated rounds of intense storms Wednesday night could produce significant flash flooding there, and another Moderate Risk is in effect. Farther north, a soaking rain from the central Plains into Iowa, southern Minnesota, and Wisconsin could lead to scattered flash flooding and rising rivers. Behind the system, a cold front dropping south from Canada will bring noticeably cooler air into the northern Plains by Wednesday. Farther east, the weakening nor'easter will exit into the Canadian Maritimes by Wednesday. High tides will still bring coastal flooding at times to part of the Southwest and Mid-Atlantic coasts. High pressure building in behind the storm will bring dry weather and a warming trend, with highs near 90 degrees across the Southeast by midweek, while heat indices in South Texas exceed 105 degrees. Out West, a Pacific front will bring rain to the Pacific Northwest on Tuesday, and offshore winds will begin a significant warning trend across California. Eovino Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$