Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0343 AM CDT Sat Sep 27 2025 Valid 301200Z - 051200Z ...DISCUSSION... Potential Tropical Cyclone Nine may approach coastal South Carolina early in the period, before probably stalling near or offshore, then accelerating away from the coast into the western Atlantic. This is likely to be influenced by some combination of a lingering frontal zone near the Carolina coast, an initial increasing proximity of Humberto to its east, and cool surface ridging building across the Northeast through the lee of the Appalachians, in the wake of an amplifying mid-level trough off the north Atlantic coast during the early to middle portion of next week. However, even if it does migrate inland at some point, as some model output indicates is at least possible, probabilities for the inland advection of a sufficiently moist and buoyant boundary layer to support an appreciable risk for tornadoes still appears low. Otherwise, developments within the westerlies off the mid-latitude Pacific into North America remain unclear through the latter portion of the coming week into next weekend. Guidance now appears to indicate a more amplified regime, including one or more short wave perturbations emerging from evolving large-scale troughing across the West. However, a slow to develop moist return flow off the Gulf into the interior U.S. may continue to preclude an appreciable risk for organized severe thunderstorm development.
