Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue May 13 2025 05:54:55 ACUS01 KWNS 130554 SWODY1 SPC AC 130553 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Tue May 13 2025 Valid 131200Z - 141200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE NC/VA/WV VICINITY...NORTHERN GREAT PLAINS...AND DEEP SOUTH... ....SUMMARY... Isolated severe thunderstorms are possible: 1) today in vicinity of Virginia-North Carolina-West Virginia, 2) during the late afternoon to mid-evening over a portion of the Deep South, and 3) this evening into early morning Wednesday in parts of the northern Great Plains. ....NC/VA/WV vicinity... A mid/upper trough centered on the Mid to Deep South will gradually shift east-northeastward, reaching the OH Valley to FL Peninsula by early Wednesday. The low-level warm conveyor will remain displaced well downstream across eastern NC and advance north across the Mid-Atlantic States towards the Lower Great Lakes. Early-day severe potential will be tied to this conveyor in eastern NC/VA where low-topped convection is anticipated. While instability will remain quite limited, enlarged low-level hodograph curvature and near-saturated thermodynamic profiles will offer potential for a brief tornado. West of the warm conveyor, more pronounced boundary-layer heating will occur, likely resulting in moderate buoyancy by early to mid afternoon with MLCAPE of 1000-1500 J/kg. This coupled with weak mid-level height falls should support scattered thunderstorms. Deep-layer shear is expected to remain moderate across the Piedmont, with decreasing values westward towards the trough. This renders a nebulous transition between loosely organized to pulse convection. For now, have delineated the MRGL risk where at least modest values of deep-layer shear could support multicell clusters. Isolated severe hail and damaging winds are the expected hazards, west of the coastal plain. ....AL/MS/TN vicinity... Some guidance suggests a supercell or two may develop on the backside of the departing mid-level trough. A mesoscale corridor of differential boundary-layer heating, coincident with the eastward expansion of the southern Great Plains EML across the Lower MS Valley, may support a favored corridor for late afternoon to mid-evening storm development. Despite weak low-level winds, some veering of the wind profile should yield modest hodograph curvature. This coupled with moderate mid-level west-northwesterlies will favor a conditional supercell threat. ....Northern Great Plains... A broad, but more amplified mid/upper trough will gradually shift east across the West. A downstream split in the stronger flow regime is expected over the southern Rockies to adjacent High Plains in the wake of the prior blocking pattern over the central states. This will yield a meridional mid/upper wind profile across the northern Great Plains. At the surface, a Pacific cold front will stall in the western to central Dakotas vicinity. Strong mid/upper winds will remain displaced west of this boundary, where strengthening large-scale ascent is anticipated tonight as an embedded shortwave impulse rotates through the eastern portion of the western trough. Elevated buoyancy is expected to remain weak given poor-quality low-level moisture. Still, with the strengthening effective bulk shear and forcing for ascent, a few elevated supercells are possible tonight into early morning Wednesday. Isolated severe hail should be the primary hazard, with potential for strong (but sub-severe) gusts closer to the surface front. ...Grams/Lyons.. 05/13/2025 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .