SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0159 AM CDT Mon Sep 29 2025 Valid 011200Z - 021200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Aside from low probabilities for thunderstorms across parts of the Pacific Northwest, the risk for thunderstorms appears negligible across much of the rest of the U.S. Wednesday through Wednesday night. ...Discussion... Beneath a confluent mid-level regime, in the wake of a short wave trough digging southeast of the north Atlantic coast, models indicate that the center of an expansive cool surface ridge will shift southeastward through much of the Northeast and Mid Atlantic by late Wednesday night. The weaker southwestern flank of this ridge likely will be maintained as far south and west as the southern Great Plains and northern Gulf Basin, while the frontal zone on the leading edge of the cooler air advances further offshore of the Atlantic Seaboard, in the wake of east-northeastward accelerating Humberto and Imelda. Upstream, flow across the northern mid-latitude Pacific into North America will continue to trend a bit more zonal through at least this period. An initially deep, occluded surface cyclone offshore of the southern British Columbia/Pacific Northwest coast is forecast to undergo rapid weakening near Vancouver Island. However, as a modest residual mid-level cold pool migrates inland, it may contribute to sufficient destabilization for scattered weak thunderstorm activity west of the Cascades and farther inland across parts of the northern intermountain region. ..Kerr.. 09/29/2025
