SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1235 AM CDT Tue Sep 30 2025 Valid 301200Z - 011200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe storms are unlikely today and tonight. ...Synopsis... An expansive mid-level ridge will persist from the MS Valley into the upper Great Lakes a pair of TCs and an upper low intensify off the Atlantic Seaboard. As these storms are forecast to recurve, dry offshore flow is expected in their wake over the entirety of the eastern CONUS as surface high pressure intensifies and move south out of eastern Canada. The cooler and drier surface conditions should limit thunderstorm potential outside of coastal FL and the southern Appalachians where shallow buoyant profiles remain. A large upper low will gradually expand over the western third of the CONUS through tonight. While southwesterly flow aloft is forecast to increase, dry surface conditions are expected as remnant moisture is scoured east. Scattered thunderstorms remain possible over the Intermountain West and along a lee trough across the central High Plains. The presence of only modest surface moisture and poor lapse rates will limit diurnal destabilization across much of the CONUS. While an isolated stronger storm remains possible over the northern Great Basin and High Plains, meager buoyancy and modest overlap with stronger vertical shear will largely preclude severe potential. ..Lyons/Moore.. 09/30/2025
