090 ACUS03 KWNS 191933 SWODY3 SPC AC 191932 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0232 PM CDT Sat Jul 19 2025 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN PLAINS...AND FROM THE TENNEESSEE VALLEY TO SOUTH CAROLINA... ...SUMMARY... At least isolated severe storms appear likely across parts of the northern Great Plains and parts of the Tennessee Valley into southern Atlantic Seaboard Monday through Monday night. ...MT into the northern Plains... A positive-tilt upper trough will remain over the Pacific Northwest on Monday, with an upper ridge over the Plains. Moderate southwest to west winds aloft will exist over MT and into ND and northern MN around the periphery of the ridge, with midlevel temperatures remaining relatively cool. At the surface, low pressure will deepen over the central High Plains with strong heating, and southeast winds around a Great Lakes high will maintain a westerly push of moist air with 70s F dewpoints across the Corn Belt. Farther northwest, lower 60s F dewpoints will be common into much of eastern MT. This will result in strong instability NE/IA into the Dakotas, with lack of large-scale ascent the primary mitigating factor to a larger area of severe potential. That said, it is likely that at least isolated severe storms develop over western NE into the Dakotas where the air mass gets uncapped. Conditionally, large hail and damaging winds will be possible. Farther west into MT, this region is also likely to see at least a few severe storms. Given the upper ridge, storm coverage and potential capping into the evening may mitigate the overall threat. As such, will maintain a broad area of 5% probabilities at this time, though higher probabilities may be needed in later outlooks cycles as predictability increases. ...TN Valley southeastward to the SC Coast... A weak low is forecast over SC during the afternoon as a cold front pushes south across VA and NC. The air mass across the region will remain very moist, with pockets of stronger instability. Scattered storms are likely within the instability axis, possibly in association with residual boundaries from the previous night's convection over the OH Valley. Otherwise, sufficient surface convergence and terrain effects should support widely scattered development from the southern Appalachians toward the SC Coast, with locally strong to damaging downbursts in the high PWAT environment. ..Jewell.. 07/19/2025 $$