Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Apr 20 2023 12:45:42 ACUS01 KWNS 201245 SWODY1 SPC AC 201244 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0744 AM CDT Thu Apr 20 2023 Valid 201300Z - 211200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM NORTHERN IL TO MO/AR AND CENTRAL/EAST TX... ....SUMMARY... Isolated to scattered severe thunderstorms capable of hail and severe gusts are possible from parts of mid Mississippi Valley southwestward into the Ark-La-Tex and central Texas this afternoon and tonight. ....Eastern MO to southern WI this afternoon... An embedded speed max over KS/NE this morning will progress north-northeastward around the periphery of a northern High Plains closed low, as an associated surface cyclone likewise develops from southwest IA toward western Lake Superior while occluding. Overnight convection has been slowly weakening this morning along the southern flank of a resultant MCV over southern IA. The future evolution of this convection will modulate the degree of destabilization by midday-mid afternoon from central IL to southern WI, with quicker weakening of the storms allowing greater destabilization, and more persistent storms interfering with the northward extent of the unstable surface warm sector. The southern fringes of the morning convection mark the areas most likely to recover, thus the SLGT risk has been expanded to the northeast in IL to reflect the somewhat conditional threat for damaging winds, large hail, and possibly a tornado or two given wind profiles with 40-50 kt effective bulk shear and the possibility of MLCAPE up to 1500 J/kg. ....Central/east TX through tonight... The cold front now surging into central OK and northwest TX is expected to continue into central and northeast TX by afternoon. Ascent along the front will help focus thunderstorm development in a broken band from central to northeast TX by mid afternoon, and storms will subsequently spread southeastward with the front through tonight. Deep-layer and low-level vertical shear will be rather modest along the front, with effective bulk shear of 30-40 kt and relatively straight hodographs. MLCAPE of 2500-3500 J/kg and steep midlevel lapse rates will favor strong updrafts in the moderately sheared environment. Thus, a mix of supercells and storm clusters is expected, along with a tendency for upscale growth by evening. Large hail can be expected with the initial, more discrete storms (some in excess of 2 inch diameter), and the potential for damaging winds will increase with upscale growth as convection moves from central TX toward southeast TX and the middle/upper TX coast. Any tornado threat is expected to remain rather isolated, and likely dependent on favorable storm-scale/boundary interactions. ...Thompson/Gleason.. 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) .