154 FXUS01 KWBC 150807 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Wed Jul 15 2026 Valid 12Z Wed Jul 15 2026 - 12Z Fri Jul 17 2026 ...Additional excessive rainfall likely across the Texas Hill Country... ...Anomalous heat and humidity continuing across the Northern Plains/Upper Midwest while spreading into the northern Mid-Atlantic... ...Monsoonal showers and thunderstorms develop across the interior western U.S... ...Severe thunderstorms possible early this morning across northern New England and portions of Montana; strong thunderstorms return on Thursday across northern New England... An unusually strong upper-level high has become nearly stationary over the northern tier states while building southeast toward the East Coast. This weather pattern will prolong the heat and humidity across the Northern Plains to the Great Lakes where high temperatures will remain in the 90s to lower 100s for the next few days. A cold front trailing from a deepening cyclone across eastern Canada will bring some cooler and drier air into the U.S.-Canadian border and keep the temperatures in the 80s there. Meanwhile, the heat and increased humidity will return to the northern Mid-Atlantic today and Thursday when triple digit high temperatures are expected at the hottest locations. Extreme Heat Warnings remain in effect across portions of the Northern Plains as Heat Advisories are posted for much of the Great Lakes, portions of New England and some Extreme Heat Warnings over the northern Mid-Atlantic. If you will be situated within any of these areas forecast to experience extreme heat, stay hydrated, take frequent breaks, and limit outdoor activities if possible. Severe thunderstorms are possible early today across northern New England ahead of the the cold front, and across Montana on the backside of a low pressure wave near the western end of the end. Cooler air will penetrate deeper into New England by Thursday morning under gusty westerly winds behind the cold front followed by a reinforcing shot of cooler air by Friday morning with the passage of a second cold front. In addition, some strong thunderstorms are possible later on Thursday across northern New England prior to the arrival of the second cold front. As the anomalous upper high extends across the northern tier, a slow-moving weather regime has already set up across the southern tier states. A nearly stationary front will also be sprawled from the Southern Plains to the Southeast during this period. Upper-level vortices will likely interact with the wavy frontal boundary to produce repeated rounds of showers and thunderstorms for the southern states. Near the western end of the front, a significant heavy rainfall event is forecast to linger across the Texas Hill Country over the next three days as clusters of thunderstorms could mutually amplify the smaller scale upper-level vortices to further enhance rainfall over this region under this slow-moving weather pattern. The latest rainfall forecast calls for storm total rainfall amounts of 6-8" with locally 10+ inches possible over the next couple of days, which could lead to dangerous flash flooding as soils in the area become increasingly inundated. Meanwhile, the forecast remains on track for an influx of monsoonal moisture to drive an uptick in late-day to early-evening thunderstorms over the Four Corners, Intermountain West, and the eastern portion of the Great Basin. Scattered thunderstorms are also forecast from the Deep South to the Southeast near the stationary front, which will be lifting farther north into the Mid-Mississippi and Ohio Valleys later on Thursday. A few instances of flash flooding and severe weather are possible in the strongest storms through midweek. Kong/Campbell/Asherman/Otto Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$