SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CST Thu Dec 18 2025 Valid 181300Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS COASTAL NORTH CAROLINA... ...SUMMARY... While organized severe potential may be limited today, isolated strong wind gusts may occur across portions of the Lower Ohio and Tennessee Valleys this afternoon and evening and/or across the Carolinas late tonight. ...Tennessee Valley/Lower Ohio Valley... A prominent upper-level trough centered over the northern Plains/Upper Midwest early this morning will continue to amplify and spread east-southeastward, taking on a more negative tilt tonight over the Midwest/Cumberland Plateau with intense 12-hr height falls on the order of 210m. A robust low/mid-level wind field will accompany this trough, especially into tonight with 60-80 kt winds within the lowest 1-3km AGL coincident with the modifying warm sector. But, only limited destabilization is expected ahead of the front, with forecast soundings generally exhibiting meager instability. While buoyancy will be weak, a strongly forced band of frontal convection is expected to develop and spread eastward later this afternoon into evening. Current thinking is a stable boundary layer will minimize the risk of severe wind gusts near the surface, but somewhat taller/more sustained storms could occur across the Tennessee Valley including Middle/eastern Tennessee and much of Alabama into parts of Georgia, with at least some convectively enhanced wind gust potential, possibly to near-severe levels. ...Carolinas... Some strong/locally severe storms could occur late tonight through the predawn/early morning hours of Friday, attributable to an increasingly negative-tilt upper-level trough and a related robust strengthening of the deep-layer wind field. The abatement and modification of continental/cold air inland is a key uncertainty, and some guidance such as 00z/06z NAM, may be a bit too aggressive, albeit modest/weak overall, regarding late-night near-surface-based destabilization. Primary concern is for the immediate coastal areas/Outer Banks where somewhat greater airmass modification/low-level moistening is more plausible. But it is also possible that convectively enhanced wind gusts materialize inland (including Piedmont areas) in the predawn hours.. ..Guyer/Lyons.. 12/18/2025
