SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Mon Sep 29 2025 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is low today and tonight. ...Synopsis... A sluggish upper-level pattern will be present across much of the CONUS as strong ridging continues to build over the central and eastern parts of the country. East of the ridge, TS Imelda is forecast to gradually strengthen as it approaches the Southeastern Coast. Across the West, the remnants of an upper low will transition to a weak open trough as a second elongated upper trough leisurely moves onshore across the Pacific Northwest. ...Northern Great Basin and Rocky Mountains... Ahead of the weakening upper low, strong heating of a modestly moist air mass, in combination with weak large-scale ascent should foster scattered thunderstorms across the central and southern Rockies. Modest buoyancy from diminished mid-level lapse rates amid weakening upper flow suggest little storm organization and severe potential. Farther north into NV/ID and southern MT, scattered storms are expected along an eastward-moving cold front this afternoon and evening. Moderately strong meridional flow should overspread the western Great Basin ahead of the deepening western US trough. An occasional stronger storm is possible along the front capable of sporadic strong wind gusts this afternoon. However, with only modest surface moisture (dewpoints in the 40s F) and thus limited instability (MLCAPE ~500 J/kg), widespread severe storms are not anticipated. ...Eastern FL Peninsula to Coastal GA and SC... Outer rainbands associated with Tropical Storm Imelda (centered near 25.0N 77.1W) will approach the eastern FL Peninsula and southeast Atlantic Coast late in the period. While some stronger convection may approach the coast late tonight, current forecast trajectories suggest that more substantial buoyancy/shear profiles within these bands should remain well offshore. As such, no severe probabilities have been introduced this outlook. See nhc.noaa.gov for the latest track information. ..Lyons/Moore.. 09/29/2025
