409 FXUS01 KWBC 252015 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 414 PM EDT Tue Aug 25 2026 Valid 00Z Wed Aug 26 2026 - 00Z Fri Aug 28 2026 ...Dangerous record-breaking heat continues across the South-Central U.S. into the Southwest this week... ...Scattered instances of flash flooding (level 2/5) will be possible Wednesday and Thursday across the Lower Mississippi Valley... Strong to severe storms will be possible ahead of a cold front in the Mid-South to the Ohio Valley tomorrow and into the Northeast on Thursday... A strong upper-level ridge will remain anchored across the Southwest into the South-Central U.S. into late week. This will maintain an abnormal hazardous heat across the region. Daytime highs of 100-110 degrees F are forecast across the Southern Plains for Wednesday and Thursday, while portions of the Southwest will reach upwards to the upper 90s and low 100s F in the valleys and 110s in the deserts. The urban areas of San Diego and Los Angeles are under Heat Advisories and Extreme Heat Warnings through the end of the week. With overnight temperatures providing limited relief, heat-related illness may increase, especially for those without proper hydration and adequate cooling. Accordingly, widespread Major to Extreme HeatRisk is forecast for much of the Southwest into Texas through late week. See the latest Key Messages linked at the bottom of the discussion for more information. An upper-level trough and surface cold front will begin to sweep eastward across the Mid-Mississippi Valley to the Great Lakes tomorrow, sparking chances for strong to severe thunderstorms capable of damaging winds and hail. A tornado or two may also be possible on Wednesday in the Great Lakes region, according to the Storm Prediction Center. On Thursday, the severe weather threat (level 2/5) will shift to the Northeast for threats of damaging winds, hail, and a tornado or two possible. Additionally, the High / Central Plains into the eastern Rockies will see a chance for strong to severe storms Wednesday and Thursday for mainly hazards of large hail. Across the Southwest and portions of the Rockies, monsoonal moisture will continue to move northward along the western periphery of the ridge and interact with embedded shortwave energy. This will lead to daily scattered showers and thunderstorms Wednesday and Thursday. 1-2 inch an hour rainfall rates with storms will continue to pose isolated flash-flooding concerns, particularly over sensitive terrain such as burn scars, slot canyons, etc... Father east, increasing instability and persistent Gulf moisture along a slow-moving frontal boundary will support repeated showers and thunderstorms across the Southeast into Lower Mississippi Valley. The Excessive Rainfall Outlook was bumped up to a Slight Risk on Wednesday for portions of Arkansas, Mississippi, and Tennessee due to a frontal wave enhancing the organization and coverage of storms. A Slight Risk is also forecast on Thursday from Louisiana to South Carolina as a stalled frontal boundary and shortwave energy interacts with summer instability to produce the likelihood of locally heavy rainfall. Lastly, the northern Rockies into the mountain ranges of the Pacific Northwest will continue to see elevated fire weather concerns with above average temperatures overlapping with low relative humidities and gusty winds (10-30 mph). Follow local officials on fire weather orders. Wilder/Oudit 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 $$