773 FXUS01 KWBC 231931 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 330 PM EDT Sun Aug 23 2026 Valid 00Z Mon Aug 24 2026 - 00Z Wed Aug 26 2026 ...Dangerous and record-breaking heat continues across the south-central U.S. into the Southwest... ...Isolated to scattered flash flooding and severe weather threat across portions of the Southwest and into the Rockies/Plains, Upper Midwest, and Southeast through Tuesday... A strong and persistent upper ridge centered over south-central U.S. and the Southwest will maintain very hot conditions across the southern tier. Above normal temperatures will continue to have daily afternoon highs within the upper 90s to 100s, with the highest values specifically over much of Texas, Oklahoma, eastern New Mexico, and the Desert Southwest. The combination of little to no overnight recovery and high humidity (for the Southern Plains) will allow for heat indices to reach up to 105-115 degrees, which is where widespread Major to Extreme HeatRisk is forecast. Furthermore, these abnormal temperatures are expected to break dozens of high/low daily temperatures through the week. Extreme Heat Warning and Heat Advisories have been issued across portions of the Four Corners, Southern Plains, and Lower Mississippi Valley. The anomalous summer heat wave is expected to persist through early this week and beyond. See the latest Key Messages linked at the bottom of the discussion for more information. North of the ridge, a corridor of enhanced moisture and instability will extend from the northern Rockies/Plains into the Midwest and Lower Mississippi Valley. Shortwave energy embedded within the northwesterly flow will interact with this moisture and a frontal boundary, resulting in scattered thunderstorms through Monday. By Tuesday, a system will eject eastward across south-central Canada and spread rain/thunderstorm chances into the Upper Midwest. Repeated convection and high rainfall rates may lead to excessive rainfall and isolated flash flooding, especially across the Plains into the Lower Mississippi Valley. Additionally, Storm Prediction Center highlights the potential for severe thunderstorms, damaging wind gusts, and hail across portions of the Great Basin and Rockies/Plains through Monday. Further southwest, monsoonal moisture will continue to bring daily thunderstorms across the Southwest, Rockies, and Intermountain West, leading to excessive rainfall/flash flooding concerns the beginning of this week. Meanwhile, a surface low and associated frontal boundary affecting the Northeast will gradually shift eastward, but additional upper-level energy will support lingering showers and thunderstorms into Monday across the Lower Great Lakes and northern New England. Some storms may become locally strong where sufficient instability develops, which may lead to severe weather and excessive rainfall concerns. Additionally, the trailing frontal boundary stretching across the Southeast will bring chances for severe thunderstorms, damaging winds, and excessive rainfall on a isolated to scattered basis through Tuesday. Oudit/Snell 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 $$