Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Sep 22 2025 06:02:07 ACUS01 KWNS 220602 SWODY1 SPC AC 220600 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Mon Sep 22 2025 Valid 221200Z - 231200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN NE INTO WESTERN IA/NORTHWEST MO...AND FROM WESTERN/SOUTHERN KS INTO WESTERN/CENTRAL OK AND THE EASTERN OK/TX PANHANDLES... ....SUMMARY... Severe thunderstorms will be possible this afternoon into tonight across portions of the central/southern Plains and the lower to mid Missouri Valley. Strong storms with locally damaging gusts will also be possible from parts of the Tennessee Valley into the lower Great Lakes. ....Synopsis... A rather complex upper-level pattern will cover the CONUS later today. A compact mid/upper-level low will move across the Upper Great Lakes region, while farther south, a low-amplitude shortwave trough (and possible embedded MCV) will move from the mid MS Valley into the OH Valley. Farther west, a shortwave trough initially over the interior Northwest will dig southeastward toward the central Rockies. At the surface, multiple weak surface lows may develop along a lee trough across parts of the central/southern High Plains. A cold front will move southward across the Upper Midwest and northern/central Plains. ....Central/southern Plains into the Upper Midwest... Steepening midlevel lapse rates atop seasonably rich low-level moisture will result in moderate to strong destabilization this afternoon across a large area from the central/southern Plains into parts of the Upper Midwest. Details regarding the location and coverage of diurnal storm development remain uncertain. At least isolated storms may develop near the southward-moving front from northeast NE into the Upper Midwest, and also potentially farther west and south near a surface trough and in the vicinity of any surface lows. Deep-layer flow will be relatively modest into the early evening, but sufficient to support 25-40 kt of effective shear (with the shear magnitude greater where winds may become locally backed). Initial development could evolve into strong multicells and perhaps a few supercells, with an attendant threat of large hail, localized severe gusts, and possibly a brief tornado. Some clustering will be possible with time, especially from western KS into northern OK, where an increasing low-level jet and the influence of the digging shortwave trough across the central Rockies could foster nocturnal MCS development. Any organized upscale growth would result in an increasing severe-wind threat, along with some brief-tornado potential as low-level SRH increases with time. While uncertainty remains, guidance still generally depicts relative maxima in storm coverage across eastern NE/western IA from late afternoon into the evening, and from southwest KS into northern OK during the evening and overnight. As a result, only minor modifications have been made to the Slight Risk areas. ....TN Valley into the lower Great Lakes... Scattered to numerous thunderstorms are expected later today across parts of the TN/OH Valleys, as a midlevel shortwave trough moves across a moist and uncapped environment. Guidance generally suggests an increase in low/midlevel southwesterly flow compared to yesterday, though deep-layer shear will remain modest and midlevel lapse rates are forecast to again be weak. One or more clusters may evolve and pose a threat for at least isolated damaging wind. If any pockets of stronger heating/destabilization can evolve, and/or MCV-related enhancement to the flow is stronger than currently forecast, then a Slight Risk upgrade may eventually be needed for parts of this region. ....Eastern AZ into NM... High-based convection is forecast to develop across eastern AZ and move across NM during the late afternoon and evening, within a strengthening unidirectional westerly flow regime. Buoyancy is expected to remain limited, but CAM guidance suggests potential for a relatively large outflow to develop and spread across NM, accompanied by strong to locally severe gusts. If confidence increases regarding maintenance of some organized convection associated with this outflow, then wind probabilities may eventually be needed. ...Dean/Squitieri.. 09/22/2025 $$ = = = 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) .