266 FXUS01 KWBC 191959 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 PM EDT Wed Aug 19 2026 Valid 00Z Thu Aug 20 2026 - 00Z Sat Aug 22 2026 ...Heavy rain and flash flooding threats across the Midwest, Ohio Valley and southern Arizona today, shifting east to the Mid-Atlantic coast on Thursday... ...Severe storms possible across mid-Mississippi Valley today through tonight... ... Severe storms possible across Nebraska and flash flooding possible in the Southeast on Friday... ...Dangerous heat persists in the South while building into the Southwest... Heavy rain and thunderstorms have developed across much of eastern Nebraska moving into southern portions of Iowa and northern portions of Missouri due to a cold front moving through the central plains. SPC has a slight risk for severe weather where these storms are capable of producing severe wind gusts and hail as daytime heating maximize. WPC has a slight risk of excessive rainfall also in the general area. Clusters of organized heavy showers and thunderstorms will continue traveling eastward across the central Plains toward the mid-Mississippi Valley this evening through tonight. These thunderstorms are forecast to become more focused in the mid-Mississippi Valley through tonight ahead of a low pressure wave traveling eastward. SPC has a slight risk of severe thunderstorms across the mid-Mississippi Valley and WPC has a slight risk of excessive rainfall extending farther north into the Midwest and Ohio Valley. Meanwhile, monsoonal showers and thunderstorms will be most active during the late-day hours across the Four Corners states, where the WPC has highlighted a marginal risk of Excessive Rainfall through the next couple of days. In addition, a slight risk is in place across southern Arizona for today. By Thursday, the cold front will advance farther eastward and begin to merge with the meandering front to the south. A convergence zone sandwiched between these two fronts will focus a corridor of enhanced rainfall. Heavy rain with embedded thunderstorms is possible along this corridor roughly from I-95 east to the northern Mid-Atlantic coast. WPC has highlighted this area for a slight risk of excessive rainfall mainly later on Thursday when daytime heating is maximized. In addition, SPC has highlighted a slight risk for severe weather where the main threat is damaging wind gusts. By Thursday night into early Friday, the heavy rain should temporarily exit the Mid-Atlantic coast as a low-pressure wave slides off the coast of southern New England. Another round of severe weather is possible for eastern Nebraska into Minnesota and Wisconsin Thursday afternoon into the evening. A weak low pressure system will migrate from Minnesota into the U.P. Michigan, creating a weak surface front along with dew points in the low to mid 60s to generate severe weather. SPC has outlined a slight risk of severe weather for the area where the main threat will be large hail, and isolated wind damage. On Friday, much of central and eastern Nebraska will yet again experience another round of severe weather. A low pressure system will develop along a surface trough with ample moisture and strong instability in place to initiate some supercell thunderstorms. SPC has highlight a slight risk for severe weather where main threat will be isolated to scattered damaging hail (some greater than 2 inches),and some severe wind gusts for Friday afternoon into the evening hours. As for the Southeast, scattered to numerous thunderstorms are forecast within a very moist and unstable environment along a surface trough. Single to multi-cell convection will pose the risk for excessive rainfall where WPC has highlighted a slight risk for excessive rainfall from northern portions of South Carolina to the southern portions of Virginia. Temperature-wise, the southern tier of the Lower 48 remains mired in a steamy air-mass even by mid-to-late August standards. Record highs and record warm minimum temperatures will be common with the Southeast at the heart of the anomalous heat through today. The upper ridge is forecast to strengthen over the Southwest while cool Canadian air dips further into the Great Lakes. Some cases of record-breaking warmth are expected in the Desert Southwest and Southern Plains as temperatures dip into the 40s near the Canadian border in the upper Midwest. Extreme Heat Warnings are in effect for much of the Desert Southwest, and Extreme Heat Warnings remain in effect across portions of the southern Plains to the Deep South. Heat Advisories are in effect for all of Florida and the southeast U.S. coast. Overnight lows will be so warm (low 80s in some cases) that, when combined with oppressive dew points, little-to-no relief from the scorching daytime highs will be available. Residents are advised to follow proper heat safety tips by limiting outdoor activity, staying hydrated, ensuring access to A/C or cooling centers, and checking on vulnerable friends, neighbors, and family members. Green/Kong Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$