SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1146 PM CDT Tue Sep 30 2025 Valid 011200Z - 021200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected today through early Wednesday morning. ...Synopsis... Southwesterly mid/upper flow will persist across the Pacific Northwest as an upper trough remains just offshore through the period. Large-scale ascent and cooling aloft may support isolated thunderstorms offshore and near the WA Coast/Olympic Peninsula. Further east, a lead upper shortwave trough will lift northeast across the northern Plains. A surface trough/wind shift will develop eastward across the northern/central Plains as this occurs. Southerly low-level flow will maintain modest boundary layer moisture ahead of the surface boundary. Capping will likely preclude surface-based convection, but isolated elevated thunderstorms are possible across eastern portions of the Plains toward the Upper Midwest amid weak instability and modestly steep midlevel lapse rates within the warm advection regime. Isolated showers and thunderstorms may also occur across portions of the FL Peninsula. However, thunderstorm coverage/intensity may be limited by midlevel subsidence despite a seasonally moist/unstable airmass. ..Leitman.. 10/01/2025
