SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Sun Oct 19 2025 Valid 192000Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THROUGH TONIGHT FROM THE APPALACHIANS INTO THE MID-ATLANTIC... ...SUMMARY... Low-topped convection with isolated lightning flashes may produce occasional strong-damaging gusts, and possibly a brief/weak tornado, through the remainder of this afternoon into the Appalachians and tonight into the Mid-Atlantic. ...20Z Update... Given the increasing lack of large-scale support and the weakening trend of convection near the west-central coast of Florida, severe probabilities have been removed from the Florida Panhandle/Big Bend. A shallow band of convection continues north and eastward from the upper Ohio Valley into the central Appalachians. The strongest mid-level ascent will continue into the Mid-Atlantic this evening. Despite minimal buoyancy, strong low/mid-level winds will support sporadic damaging wind gust potential. ..Wendt.. 10/19/2025 .PREV DISCUSSION... /ISSUED 1123 AM CDT Sun Oct 19 2025/ ...Appalachians this afternoon into the Mid-Atlantic tonight... A sharp midlevel trough and associated 100+ kt jet will progress from TN/KY late this morning to the Mid-Atlantic region by early Monday morning. An associated surface cyclone is in the process of occluding just north of Lake Superior, while a trailing cold front continues eastward across the upper OH Valley/Appalachians today and reaches the Atlantic coast/southern New England overnight. A narrow band of shallow convection/enhanced reflectivity coincides with the front/wind shift from eastern KY into OH as of 16z. West of the surface wind shift, low-topped convection with isolated lightning flashes continues with the primary midlevel vorticity max/left-exit region of the jet across central KY/middle TN. Buoyancy is expected to remain weak (MUCAPE of 100-300 J/kg) and the depth of the frontal convection will be marginal for charge separation and lightning production. Still, there will be some potential for downward momentum transfer of ~50 kt low-midlevel flow and isolated wind damage with the consolidated convective band this afternoon from eastern OH/KY and WV eastward into the Appalachians, and overnight into the Mid-Atlantic. ...Northeast Gulf coast this afternoon... The remnants of early morning convection persist near and south of the FL Panhandle in association with a pre-frontal wind shift and a weakening southern stream shortwave trough. Forcing for ascent is expected to weaken through the afternoon and substantial inland destabilization is unlikely given widespread clouds and weakening southerly flow components with time. Thus, any remaining severe threat will be confined to the coast and will likely end later this afternoon. ...WA coast today... A midlevel trough with associated cold air aloft and steep low-midlevel lapse rates is spreading inland. A few low-topped thunderstorms have been observed this morning along the WA coast, and a few additional storms will be possible for the next 6 hours or so. Vertical shear is sufficiently strong for some storm organization, but the odds of sustained supercells appear too low to warrant the introduction of severe probabilities.
