Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Sep 17 2025 05:51:28 ACUS01 KWNS 170551 SWODY1 SPC AC 170550 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CDT Wed Sep 17 2025 Valid 171200Z - 181200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE SOUTH-CENTRAL HIGH PLAINS... ....SUMMARY... Isolated severe thunderstorms are possible, mainly during late afternoon to mid-evening, across parts of the south-central High and Great Plains. The most likely corridor is over the Raton Mesa, where large hail, severe gusts, and a brief tornado are possible. ....South-central High Plains to southern KS/northwest OK... An upper-level jetlet will become centered across the southern Rockies/Sangre de Cristo Mountains this afternoon, south of multiple shortwave impulses drifting across the central Rockies and Great Plains. Overnight convection should aid in a consolidated outflow/cold front arcing from parts of KS to the Raton Mesa vicinity. Post-frontal upslope flow will aid in a moist airmass with a lobe of weak to moderate buoyancy banked to the I-25 corridor in southeast CO. Robust boundary-layer heating will occur in the progressively drier/more well-mixed air mass with southern extent in the southern High Plains to OK. Initial thunderstorm development will occur along the higher terrain by mid-afternoon and spread east-southeast into the evening. Additional storms should also form along the arcing front/outflow towards northwest OK/south-central KS. Convection near the Raton Mesa will be characterized by a spatially confined but favorable wind profile for a longer-lived supercell or two. A swath of large hail should be the primary hazard, with a brief tornado and localized severe gusts also possible. Overall severe threat should diminish after dusk with negative theta-e advection from the south. ....Central/eastern NE and northern KS... Moderate mid-level southwesterlies should remain confined to the central Great Plains, attendant to a shortwave impulse drifting from CO/WY to NE/SD. Confidence is very low in whether this flow regime will overlap adequate airmass recovery in the wake of extensive convective overturning this morning. Some degree of recovery might occur by late afternoon, mainly supportive of a marginal severe hail threat. But given the conditionality, will defer to later outlooks for a possible highlight. ....Western MO to northern WI... Larger buoyancy ahead of ongoing outflow in IA to KS should be relegated to a confined corridor, displaced east within a predominately weak deep-layer shear regime. This suggests more of a pulse-type strong-storm threat during peak heating in this region. ...Grams/Squitieri.. 09/17/2025 $$ = = = 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) .