Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Apr 18 2025 16:34:41 ACUS01 KWNS 181634 SWODY1 SPC AC 181633 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1133 AM CDT Fri Apr 18 2025 Valid 181630Z - 191200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND SOUTHWESTERN GREAT LAKES... ....SUMMARY... Scattered severe thunderstorms are possible from parts of the southern Plains northeastward through the mid Mississippi Valley and southwestern Great Lakes, mainly from late afternoon into early Saturday morning. Large to very large hail and severe wind gusts should be the main hazards, especially across the southern Plains where storms will be more concentrated. A few tornadoes also appear possible. ....Southern Plains to the Ozarks... Strong southwesterly mid to high-level flow will extend from the southern High Plains northeastward into the Great Lakes, downstream of a mid- to upper-level low over the Four Corners states. A cold front was analyzed from the Low Rolling Plains northeastward through central OK late this morning. This portion of the front will continue southeastward into the I-44 corridor but decelerate towards late afternoon. A dryline extends southward from the front over the TX Big Country. Despite widespread mid/high-level cloudiness, filtered heating of a moist/destabilizing airmass will likely result in a weakened cap by late afternoon. Initial supercell development should pose a threat for large to very large hail, potentially up to 2-3 inches in diameter. Model forecast hodographs and ample PW suggest a strong tendency towards upscale growth into an HP supercell and linear segment this evening from south-central OK northeastward towards the western part of the Ozark Plateau. Coincident with this expected convective mode evolution, an increase in the severe/damaging wind threat is anticipated. The threat for a few tornadoes remains apparent, especially across parts of OK along/south of the front, as favorable low-level shear will be present this evening where surface-based supercells and mesovortex potential may still exist. ....Lower MI to Mid Mississippi Valley... In wake of weakened thunderstorm activity across Lower MI, a warm sector will attempt to spread northward and destabilize across parts of the mid MS Valley and southern/central Great Lakes this afternoon. An upper trough will only slowly encroach on the Upper Midwest through late tonight. As a result, southwesterly flow aloft will be maintained and limited southeastward progression of a cold front is forecast. Model guidance continues to indicate surface-based thunderstorm development will be inhibited until peak heating, when frontal forcing and gradual erosion of the cap leads to isolated storms developing from MO northeastward towards the southwest Great Lakes. Uncertainty remains regarding timing, overall thunderstorm coverage, and the exact evolution of this activity. Nonetheless, strong shear through a deep layer and adequate buoyancy (due in part to steep mid-level lapse rates), will support organized thunderstorms. The stronger thunderstorms will probably pose a risk for severe hail and damaging winds. This severe threat may persist for much of the evening, and perhaps continuing into the early overnight hours. ...Smith/Thornton.. 04/18/2025 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .