Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 01 2025 19:54:47 ACUS01 KWNS 011954 SWODY1 SPC AC 011953 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Fri Aug 01 2025 Valid 012000Z - 021200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE CENTRAL HIGH PLAINS INTO WESTERN SOUTH DAKOTA... ....SUMMARY... Scattered severe thunderstorms are possible across parts of the High Plains this afternoon and evening. Large to very large hail, a couple of tornadoes, and severe gusts are possible. ....20z Update... The forecast largely remains on track. The primary update was to introduce 5% tornado probabilities across portions of northwest SD ahead of a pronounced MCV where initial stages of thunderstorm development are noted in recent GOES/lightning data. Visible imagery shows slowly building cumulus within the southeasterly flow regime ahead of the MCV as temperatures warm into the mid/upper 70s. Forecast soundings suggest this is adequate for surface-based convection, and depict enlarging hodographs later this evening as the nocturnal jet strengthens. While localized, this environment may be somewhat more favorable for tornadoes compared to adjacent portions of SD. Elsewhere, minimal changes are required. 5% wind probabilities were amended slightly across portions of the Carolinas to better reflect recent thunderstorm development/trends. See the previous discussion below as well as MCDs #1860-1862 for additional details. ...Moore.. 08/01/2025 ..PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Aug 01 2025/ ....High Plains... Water-vapor imagery late this morning shows a few disturbances undercutting an upper ridge currently over the High Plains/Alberta. An MCV is slowly moving eastward near the MT/WY/SD/ND border, a more pronounced upper trough will remain over the northern Rockies and adjacent high plains of MT, and a more subtle disturbance will move east-northeastward across the central Rockies. A residual frontal zone draped generally south-north abutting the higher terrain is providing a focus for richer moisture east of this boundary over the High Plains. Surface dewpoints will likely range from the mid 50s to the lower 60s across much of the Slight Risk. A belt of slightly stronger westerly upper flow is forecast across the central High Plains which will act to elongate hodographs. Additionally, a plume of steep 700-500 mb lapse rates (7.5 to 9 deg C/km) will contribute to MLCAPE 2000-3000 by mid-late afternoon. The aforementioned low-amplitude disturbance over the central Rockies coupled with low-level upslope flow/orographic effects will result in initial thunderstorm development over the high terrain and the Cheyenne Ridge. The best overlap between buoyancy and shear is expected from western SD into northeast CO/WY/NE Panhandle border region. Model ensemble data suggest a few favored corridors for severe may result. The most notable area may focus near the Cheyenne Ridge and adjacent northeast CO where supercell potential appears greatest. Large to very large hail and a tornado or two are possible with this activity before gradually transitioning to primarily a risk for severe gusts. One other area of interest is across northwest SD, where an MCV moving slowly into the region could result in a focused area of thunderstorms. Increased low-level convergence and low-level vertical shear near this MCV could lead to a greater threat for all severe hazards, including large hail and perhaps a brief tornado or two. ....Carolinas into Georgia-Alabama-Mississippi... A seasonably moist airmass was sampled by 12 UTC area raobs this morning (near 16 g/kg lowest 100-mb mean mixing ratio). Visible-satellite imagery shows extensive low cloud cover across central and eastern NC near and behind the wind shift/cold front. Farther west, initial cumulus field development is noted over the southern Appalachians where strong heating is occurring and farther south/southeast over the Piedmont and to the coastal plain. As temperatures continue to warm through early afternoon, erosion of convective inhibition will result in scattered storms favoring the higher terrain and eventually near the wind shift. High PW (2 inches or greater) and diurnally steepened surface to 1.5 km lapse rates will support a risk for wet microbursts with the more intense water-loaded downdrafts. Localized gusts 50-65 mph are possible and scattered pockets of wind damage may result. $$ = = = 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) .