Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Apr 20 2023 16:28:14 ACUS01 KWNS 201628 SWODY1 SPC AC 201626 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Thu Apr 20 2023 Valid 201630Z - 211200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL U.S. FROM SOUTHERN WI TO SOUTH TX... ....SUMMARY... Scattered severe thunderstorms will be possible across a portion of the central states from southern Wisconsin to south Texas, mainly from mid-afternoon into this evening. Damaging winds and large hail should be the primary hazards in terms of coverage. A few tornadoes will also be possible, especially across northern Illinois and southern Wisconsin. ....Mid-MS Valley to southern WI... Elevated convection persists across portions of southern WI and IL, but appears to be weakening. Subsidence in its wake has yielded cloud breaks immediately ahead of the primary surface cyclone over central IA, which will yield destabilization into this afternoon across the Mid-MS Valley and IL to southern WI. The cyclone will initially track northeast into western WI before occluding northward, aided by an 80-90 kt 500-mb jetlet curling across IA into central WI. The degree of surface-based destabilization remains somewhat uncertain with a confined warm/moist sector ahead of the eastward-moving cold front. But guidance is largely insistent that a narrow plume of moderate MLCAPE of 1000-1500 J/kg should develop, as upper 50s to low 60s surface dew points in eastern IA and northeast MO advect northeast. The synoptic pattern will support strong effective bulk shear along with an enlarged low-level hodograph favorable for discrete supercells consolidating into small clusters. As such, have increased tornado probabilities and expanded the cat 2-SLGT risk northward. Otherwise, a mix of scattered large hail and damaging wind will be possible, but the overall threat will likely be spatially and temporally confined given the narrow warm/moist sector, resulting in severe potential rapidly weakening in the early evening roughly east of the IL/IN border longitude. ....Central/east TX to AR... The cold front surging south-southeast towards the Concho Valley of west-central TX and the Ozark Plateau is expected to help focus scattered to widespread thunderstorms along and ahead of it this afternoon and evening. Large buoyancy with MLCAPE in excess of 2500 J/kg, supported by steep mid-level lapse rates, will primarily reside across central to south TX where low-level shear should remain weak. But sufficient deep-layer shear, although somewhat parallel to the front, should support initial supercells consolidating into several clusters and one or more MCSs. Farther northeast across the Ark-LA-Tex into AR, low-level shear will be comparatively greater but buoyancy will be relatively less. Large hail can be expected with the more discrete storms (some in excess of 2 inch diameter, especially across central to south TX), and the potential for damaging winds will increase with upscale growth this evening. The tornado threat is expected to remain unfocused and short-lived, likely dependent on favorable storm-scale/boundary interactions. ...Grams/Thornton.. 04/20/2023 $$ = = = 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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .