SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1150 PM CDT Sun Sep 28 2025 Valid 301200Z - 011200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms appears negligible across the U.S. Tuesday through Tuesday night. ...Discussion... Latest model output indicates little change from prior runs concerning the larger-scale pattern evolution through this period. In the wake of a significant digging short wave trough, downstream of amplified mid-level ridging slowly shifting eastward through the Hudson Bay/Ontario/upper Great Lakes vicinity, models indicate that expansive cool surface ridging will begin to build across much of the eastern Canadian provinces through Great Lakes, Northeast and Mid Atlantic by late Tuesday night, beneath a strongly confluent regime. Upstream, a significant mid-level trough and associated deep lower/mid-tropospheric cyclone are forecast to continue slowly approaching southern British Columbia and Pacific Northwest coastal areas, preceded by a couple of weak short wave perturbations accompanied by modestly deepening surface troughing across the Canadian Prairies into the lee of the northern U.S. Rockies. In lower latitudes, within a belt of weaker flow to the south of a blocking mid-level high lingering over the Midwest/middle Mississippi Valley, weak mid-level troughing is forecast to dig offshore of the Texas Gulf coast into the western Gulf Basin. As a downstream trough begins to slowly progress offshore of the south Atlantic Seaboard, guidance generally indicates that Imelda will slowly accelerate eastward, further away from the south Atlantic Seaboard. As this regime evolves, it is possible that residual low-level moisture and/or cooling aloft may contribute to areas with sufficient destabilization for scattered thunderstorm development, from near the Pacific Northwest coast, across the Rockies and parts of the Upper Midwest. Orographic forcing, and lift associated with a digging perturbation within cyclonic flow across the mountains of western North Carolina and Georgia, may support additional thunderstorm development Tuesday afternoon. However, it appears that this will be mostly modest to weak in intensity, with generally negligible risk for severe weather. ..Kerr.. 09/29/2025
