178 FXUS01 KWBC 270609 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 208 AM EDT Thu Aug 27 2026 Valid 12Z Thu Aug 27 2026 - 12Z Sat Aug 29 2026 ...Heavy rainfall and severe thunderstorm threat across portions of the Mid-Atlantic, Ohio Valley, and Northeast on Thursday... ...Heavy rainfall threat continues across the Lower Mississippi Valley/Southeast and Mid-Atlantic through... ...Dangerous record-breaking heat continues across the South-Central U.S. into the Southwest this week... An amplified pattern continues with a persistent upper-level ridging across the Four Corner and Southwest U.S., while broad troughing extends into eastern U.S. A series of northern-stream shortwaves will progress eastward, which will help push the frontal boundary over the Great Lakes/Ohio Valley into the Northeast, Mid-Atlantic, Southeast, and Lower Mississippi Valley. Increasing low-level moisture and instability ahead of the slow-moving frontal boundary will support showers and thunderstorms, which may lead to heavy rainfall/flash flooding risk across the Northeast/Mid-Atlantic into the Southeast and Gulf Coast on Thursday. Additionally, locally strong to severe storms may develop across the Northeast and Mid-Atlantic, which may produce lightning, hail, isolated tornadoes, and damaging winds. On Friday, much of the northern portion of the cold front moves offshore, while the trailing front stalls across the Mid-Atlantic into the Southeast. This will continue the severe thunderstorm and flash flooding threat along the boundary. The frontal boundary will also drape across the central/southern Plains northward into the northern Rockies/Plains, bringing chances for scattered showers and thunderstorms along the boundary. As the slow-moving boundary interacts with moist and unstable airmass, clustering of thunderstorms may develop. This will lead to a flash flooding risk across central/southern Plains and a severe thunderstorm threat across the central Plains and northern Rockies for Thursday. On Friday, the severe weather and heavy rainfall threat moves into the northern/central Plains as the frontal boundary lifts northward. Across the southwest, monsoonal moisture will continue to extend northward around the western periphery of the ridge, supporting diurnally driven thunderstorm across the Southwest into the Rockies and Great Basin through Friday. Strong organized storms may produce isolated flash flooding, especially over burn scars, urban areas, and slot canyons. The persistent upper-level ridge continues to bring dangerous heat across the Southwest and portions of Texas through Friday. Daytime highs in the upper 90s to low 100s, with isolated areas reaching between 100-115 degrees in the Southwest. Record-breaking overnight temperatures will limit recovery from the heat, which may result in heat-related illnesses for those without adequate cooling and hydration. Therefore, expect Major to Extreme HeatRisk across portions of the Southwest and Southern Texas. See the latest Key Messages linked at the bottom of the discussion for more information. Otherwise, temperatures will somewhat cool over the central and southern Plains as the frontal boundary moves southward. Additionally, a cold front and a upper-level trough will move over the Pacific Northwest bringing cooler temperatures and chances for showers across portions of the Intermountain West. 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 $$