Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 21 2025 17:41:03 ACUS02 KWNS 211740 SWODY2 SPC AC 211739 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1239 PM CDT Sun Sep 21 2025 Valid 221200Z - 231200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHWEST/SOUTH-CENTRAL KANSAS...WESTERN/CENTRAL OKLAHOMA... THE EASTERN TEXAS/OKLAHOMA PANHANDLES... AND SOUTHEASTERN NEBRASKA INTO SOUTHWESTERN IOWA/NORTHWESTERN MISSOURI... ....SUMMARY... Scattered severe thunderstorms will be possible on Monday across portions of the central/southern High Plains and the low to mid Missouri Valley. ....Synopsis... A broad troughing pattern with two embedded upper-lows will be in place from the Northern Rockies into the Great Lakes region, with high pressure building in across the West. A diffuse frontal boundary will extend from the upper Great Lakes region into the central High Plains. Much of the central/southern Plains is expected to remain strongly capped through much of the day, with late thunderstorm development expected as the front shifts southward overnight. ....Central and Southern Plains... Convection will move across Oklahoma late in the D1 period on Sunday. In the wake of this convection, appreciable MLCIN is expected across much of western Oklahoma into Kansas. Strong daytime heating is expected under broken mid to high level clouds. Daytime temperatures are expected to get into the mid to upper 80s with convective temps approaching and exceeding 90 F. This should delay thunderstorm development into the evening as the cooling from the upper wave and cold front approach from the west. Given the late development and linear forcing, mode is likely to be linear/MCS with potential for hail early on with any more discrete cells that can form along and ahead of the front in western Kansas. A southerly low-level jet is expected to steadily increase through the evening, with low level curvature of the hodographs noted from 00z onward. This may support embedded circulations within the more linear mode and potential for some tornado risk overnight. For now, confidence is low in a tornado risk developing because of the late timing of the upper wave and mode concerns. A Slight Risk was maintained and expanded eastward into eastern/northern Oklahoma with this outlook. ....NE/IA to Lake Michigan... Thunderstorm development is expected in the afternoon across the diffuse boundary from Nebraska to the Lake Michigan region. Modest lapse rates and moderate instability along this zone will support some multicells capable of some hail or damaging wind gusts. Confidence is greater in coverage of storms and more concentrated severe risk across portions of eastern Nebraska into southern Iowa. While deep layer shear will be modest around 20-30 kts, a few instances of large hail may be possible across eastern Nebraska before a transition to more of a damaging wind threat. A Slight Risk was added to account for this risk. ....Tennessee Valley to the Lower Great Lakes... A weak mid-level shortwave trough is forecast to move through the Ohio Valley on Monday with moderate instability forecast ahead of it. An uncapped air mass and some moderate upper-level support in a broader zone of weak, but persistent isentropic ascent should support scattered thunderstorm development. Lapse rates will be poor, but modest effective shear amid 20 to 30 knots of mid-level flow may support some organized multicells capable of damaging wind gusts Monday afternoon/evening. ...Thornton.. 09/21/2025 $$ = = = 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) .