Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 24 2025 19:54:17 ACUS01 KWNS 241954 SWODY1 SPC AC 241952 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Jul 24 2025 Valid 242000Z - 251200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDWEST/GREAT LAKES... ....SUMMARY... Locally damaging thunderstorm wind gusts are possible from parts of the Great Lakes to the central and southern Plains this afternoon and evening. Isolated severe storms will also pose a risk of hail and severe wind gusts over portions of the northern and central High Plains. ....20z Update... The previous forecast largely remains on track. Thunderstorm development is underway across portions of northern IL, which should intensify and track into northern IN and southern MI through the evening hours. Severe hail/wind risk probabilities were reduced across far northern lower MI due to the recent passage of deep convection and an influx of cooler/lower theta-e air. See the previous discussion below as well as MCDs #1771 and #1772 for additional details. ...Moore.. 07/24/2025 ..PREV DISCUSSION... /ISSUED 1134 AM CDT Thu Jul 24 2025/ ....Northern Lower Michigan... Ahead of an MCV, a well-organized cluster of storms will pose at a short-term severe risk across far northern Lower Michigan early this afternoon, although there is some potential for additional development southwestward along the front this afternoon. ....Midwest/Lake Michigan vicinity to south-central Plains... Aside from an MCV nearing northern Lake Michigan, at least one additional eastward-moving MCV exists across eastern Iowa, nearing the southwest Wisconsin/northwest Illinois border vicinity as of midday. Some multi-layer cloud debris still persists, and a pre-frontal veering of winds (westerly component) has occurred in some areas. However, heating of a very moist air mass (70s F surface dewpoints) will lead to strong destabilization (2500-4000 J/kg MLCAPE) and relatively weak boundary-layer inhibition this afternoon near/ahead of the front. Most 12z global guidance/HREF members are more aggressive in the coverage/intensity of convection than morning HRRR/RRFS/MPAS runs, particularly for northern portions of Illinois/Indiana into Lower Michigan. Where deep convection does develop/sustain this afternoon, MCV-aided enhancement of low/mid-tropospheric flow will support some well-organized bands/clusters of storms with wind damage as the most common severe risk across northern Missouri, northern portions of Illinois/Indiana, into Lower Michigan. A more localized/pulse-type severe risk is anticipated farther southwest into southern Kansas/northwest Oklahoma. ....High Plains... Moderate instability will develop across parts of the northern/central High Plains this afternoon. Large-scale ascent will tend to be weak behind a departing mid-level shortwave trough. Even so, convective development should occur near the adjacent higher terrain this afternoon. Effective shear of 25-40 kt will support some updraft organization. Initially discrete cells may pose an isolated threat for hail. Some outflow amalgamation/mergers could eventually occur, with a threat of strong to locally severe gusts spreading eastward into the evening before convection eventually weakens. Farther south across portions of the southern High Plains, scattered to numerous thunderstorms are also expected to develop this afternoon/early evening. Deep-layer shear will remain weak across this region, but localized strong to severe outflow gusts may still be possible. $$ = = = 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) .