Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Sep 25 2025 06:00:24 ACUS01 KWNS 250600 SWODY1 SPC AC 250558 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Thu Sep 25 2025 Valid 251200Z - 261200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE EAST COAST FROM CENTRAL GEORGIA NORTH TO SOUTHERN NEW ENGLAND AND ACROSS PORTIONS OF THE SOUTHWEST... ....SUMMARY... Scattered thunderstorms are expected from the Southeast to New England Today. Isolated damaging wind gusts and a brief tornado will be possible with the strongest storms. Additional strong storms are expected across the Southwest, posing a risk for marginally severe hail and wind. .... Synopsis ... A closed midlevel low over the Great Lakes will continue to weaken/open into a positively-tilted trough across the eastern US. As this occurs, a broad/diffuse midlevel jet on the downstream side of the trough will move east toward the I95 corridor. Farther west, a seasonably strong midlevel low will dig southeast from central California into southern California/western Arizona, with cooler midlevel temperatures and increasing midlevel flow overspreading portions of the Southwest. At the surface, a low across Kentucky at the start of the forecast period will quickly lift northeast into southern New England by early Friday morning. As this occurs, a warm front will quickly lift north through the Mid-Atlantic into southern New England. Widespread clouds and precipitation will likely accompany the warm front as it lifts north. .... Mid-Atlantic northeast into Southern New England ... Widespread cloud cover is expected across much of the area in the wake of morning precipitation limiting daytime heating resulting in poor low-level lapse rates. Additionally, saturated, nearly moist-adiabatic midlevel profiles will limit buoyancy generation. That said, the presence of an approaching trough, modest midlevel flow, and an eastward moving surface cold front should support widely scattered to scattered thunderstorms by mid afternoon. Precipitable water values in excess of 2 inches, supported by the nearly saturated moist-adiabatic midlevel profiles, should yield some wind damage threat as wet downbursts/microbursts will be possible. However, the poor thermodynamic environment described previously should limit a more widespread severe event as intense updrafts may struggle to develop. This scenario appears to be supported by the 00Z HREF members which struggle to produce much in the way of updraft helicity and are unable to produce any updrafts in excess of the 99.85 percentile. Forecast kinematic profiles support some potential for a tornado or two as any residual boundary from the early morning precipitation would provide a local low-level vorticity reservoir. Additionally, any thunderstorm that could interact with the lifting warm front would also pose at least some tornado threat. If the expectation of poor thermodynamics changes, and the degree of instability increases, the corresponding severe threat would categorically increase as well. This will be monitored in subsequent forecasts. .... Central Georgia northeast into the Mid-Atlantic ... Widely scattered to scattered thunderstorms may develop during the afternoon along the slowly advancing surface front. The thermodynamic environment here is slightly better than farther north, however, the kinematic environment is slightly worse. That said, a few strong, damaging thunderstorm wind gusts may be possible with the strongest storms. .... Southwest US ... As cooler midlevel temperatures associated with the midlevel low overspread Arizona, thunderstorms are expected to develop along the higher terrain stretching from southeast Arizona northwest into far southeast Nevada and southwest Utah. Steep low-to-mid-level lapse rates atop surface dewpoints in excess of 50F will yield most-unstable CAPE values between 750-1500 J/kg. The combination of instability, lapse-rates, and seasonably low freezing level temperatures will yield the potential for marginally severe hail and wind gusts with the strongest storms. ...Marsh/Halbert.. 09/25/2025 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .