Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jul 18 2025 16:07:55 ACUS01 KWNS 181607 SWODY1 SPC AC 181606 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1106 AM CDT Fri Jul 18 2025 Valid 181630Z - 191200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF VIRGINIA AND NORTH CAROLINA...AND WESTERN PARTS OF THE MIDWEST... ....SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a couple of tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and North Carolina this afternoon. ....Virginia/North Carolina to the Mid-South... Late morning surface analysis places a stationary front draped from west to east from the mid MS Valley eastward into the Mid-Atlantic states. Visible satellite/radar mosaic imagery shows a couple of weak MCVs moving east over the northern VA/MD vicinity and over far eastern KY. The latter disturbance will probably prove instrumental in aiding storm development across VA into northern NC this afternoon. South of the front, rich low-level moisture and heating will act to offset weak mid-level lapse rates and yield moderate to strong buoyancy from southeast MO eastward to the Mid-Atlantic coast. Early indications of a swelling cumulus field over the WV/VA mountains will gradually evolve into a cluster of storms as convective inhibition continues to erode through early afternoon. Other clusters of storms will develop and move west to east given marginal deep-layer mean westerly flow. Although small hail 0.50-1.00 inch in diameter is possible with the strongest cores, the primary hazard with the stronger storms will be damaging gusts (50-65 mph) with the more intense water-loaded downdrafts. This activity will likely diminish by the early to mid evening. ....South Dakota/Nebraska into Minnesota/Iowa... Gradual low-level moistening is forecast through this evening ahead of a weak front forecast to be in place over the eastern Dakotas into western NE. An initially appreciable capping inversion will inhibit surface-based storm development until heating gradually weakens inhibition by late afternoon. A very unstable airmass is forecast by late afternoon/early evening, but nebulous forcing lends uncertainty in terms of storm development/timing. Models suggest storms will primarily develop this evening associated with strengthening low-level theta-e advection. Supercells are possible early in the convective life cycle with a risk for all hazards, including the possibility for a couple of tornadoes, but large hail may be the main hazard. Upscale growth into a cluster or MCS is possible near the terminus of a southwesterly 850-mb LLJ with severe gusts the becoming the primary threat. Models vary considerably whether storm intensity is maintained through much of the overnight and beyond the Day-1 period, or if a gradual diminishing in severe occurs. ....Great Basin into Wyoming and Far Southern Montana... Initially high-based convection should develop this afternoon across parts of the Great Basin into WY as modest ascent associated with a weak/low-amplitude mid-level impulse spreads eastward across these areas. Steep low/mid-level lapse rates and a deep, very well-mixed boundary layer should support isolated severe gusts with the stronger thunderstorms. Somewhat greater low-level moisture should be present this afternoon across parts of southern MT into northern/eastern WY, generally along/east of the Bighorn/Laramie Mountains. Isolated severe hail may occur with marginal supercells given greater instability/shear forecast across these areas. ...Smith/Weinman.. 07/18/2025 $$ = = = 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) .