Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 19 2025 05:08:13 ACUS01 KWNS 190508 SWODY1 SPC AC 190506 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1206 AM CDT Fri Sep 19 2025 Valid 191200Z - 201200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO TONIGHT ACROSS PARTS OF SOUTHWESTERN NEBRASKA INTO WESTERN AND CENTRAL KANSAS... ....SUMMARY... Strong thunderstorms may impact parts of southwestern Nebraska into western and central Kansas late this afternoon and evening, accompanied by at least some risk for severe hail and wind. ....Discussion... Little change to the larger-scale pattern is forecast through this period, with the stronger/more amplified flow remaining confined to the northern mid-latitudes. This includes a significant, slow moving trough with several embedded perturbations pivoting around a mid-level circulation digging through the Canadian Maritimes. It appears that this will support renewed offshore cyclogenesis, with trailing intrusions of cool air continuing to overspread the Northeast and Mid Atlantic. Upstream, the exit region of a strong mid/upper jet may continue to nose across the northeastern Pacific through British Columbia coast vicinity. In between, and at lower latitudes, weaker split flow will persist across much of the U.S., with embedded troughing in one branch slowly shifting east of the northern Great Plains, while troughing in another remains quasi-stationary across the Southeast and offshore of the California coast. ....Central Great Plains... On the southwestern flank of the troughing slowly shifting toward/into the mid/upper Mississippi Valley vicinity, a notable smaller-scale perturbation is generally forecast to continue digging southwest through south of the Black Hills vicinity, before turning eastward near/northeast of the lower Missouri Valley later today through tonight. It appears that this will be accompanied by moderate strengthening of northwesterly mid-level level flow (to 30-50 kt around 500 mb), near the southern periphery of a modest mid-level cold pool (-12 to -14 C around 500 mb). With sufficient destabilization, associated strengthening of deep-layer shear and forcing for ascent may become at least conditionally supportive of supercells and perhaps an organized upscale growing cluster. Although there is notable spread among the various model output, a zone of strengthening differential surface heating, to the northeast of a modest developing lee surface low, may provide the focus for destabilization and thunderstorm initiation across parts of southwestern Nebraska into northwestern Kansas late this afternoon. By this evening, as convection progresses toward west central/central Kansas, forcing for ascent on the nose of a modestly strengthening southwesterly low-level jet (in excess of 30 kt around 850 mb) may maintain convective development and support an upscale growing, east-southeastward propagating cluster into the overnight hours. ...Kerr/Halbert.. 09/19/2025 $$ = = = 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) .