SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0735 AM CDT Sun Oct 19 2025 Valid 191300Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE UPPER OHIO VALLEY/CENTRAL APPALACHIANS INTO THE MID ATLANTIC AND SOUTHERN NEW ENGLAND...AND THE NORTHEAST GULF COAST... ...SUMMARY... Isolated strong to severe storms are possible this morning from south Alabama into southwest Georgia and the Florida Panhandle. Localized wind damage will be possible later today from upper Ohio Valley/central Appalachians into parts of the Mid Atlantic. Late tonight, localized wind damage and possibly a brief tornado will be possible from the northern Mid Atlantic into parts of southern New England. ...Synopsis... Water-vapor imagery this morning shows a powerful mid- to upper-level trough from western Ontario southward to the central Gulf Coast. This upper feature will attain a negative tilt as it moves towards the Eastern Seaboard tonight. A cyclone analyzed this morning over Lake Huron will move north-northeastward toward Hudson Bay, while a trailing cold front will push east-southeastward through parts of the Southeast, Ohio Valley, and Mid Atlantic. ...FL Panhandle vicinity... An ongoing band of convection will continue to move eastward across the northeast Gulf Coast as the airmass attempts to slowly destabilize ahead of it. The latest surface observations confine the richer moisture to the immediate coastal counties (i.e., beaches and bays) of the FL Panhandle, where upper 60s to low 70s deg F dewpoints reside. Relatively poor lapse rates will limit updraft vigor and the overall coverage/intensity of strong to locally severe storm activity. Nonetheless, the moist low levels in the presence of moderate speed shear in the surface-2km layer will perhaps support an isolated threat for a brief/weak tornado and/or a damaging gust. This activity will likely weaken towards midday as large-scale ascent focuses farther north and away from the region. ...Eastern OH into the central Appalachians and Mid Atlantic vicinity... Buoyancy will remain quite limited through most of the day along/ahead of the cold front from the upper OH Valley/central Appalachians into the Mid Atlantic. However, low/midlevel flow will be strong, with 40-50 kt in the 850-700 mb layer. Recent convection-allowing model guidance agrees in showing a developing low-topped convective band initially over eastern OH spreading into western PA coincident with weak instability. Have correspondingly adjusted the western bound of the wind risk to account for this model trend. Late in the period, somewhat richer low-level moisture (with dewpoints in the low 60s F) will advect inland into northern parts of the Mid Atlantic and southern New England. Buoyancy may become sufficient for somewhat deeper convection, as indicated by a modest increase in HREF calibrated thunderstorm probabilities between 06-12Z. With strong low-level flow/shear in place, locally damaging wind and possibly a brief tornado could accompany convection along the front into early Monday morning. ..Smith/Bentley.. 10/19/2025
