Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Oct 03 2023 17:32:41 ACUS02 KWNS 031732 SWODY2 SPC AC 031730 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Tue Oct 03 2023 Valid 041200Z - 051200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN PLAINS... ....SUMMARY... Scattered severe thunderstorms appear likely Wednesday afternoon and evening across parts of the southern Plains. Large to very large hail and severe wind gusts, some of which could be significant, will be the main threats. ....Synopsis... An upper trough over the Plains and Rockies Wednesday morning will advance eastward towards the MS Valley through the period. The primary surface cyclone is forecast to be located over Ontario, and it should continue developing northeastward through the day. A trailing cold front will sweep east-southeastward across the Upper Midwest and mid MS Valley, while the trailing/southern portion makes slower southward progress across the central/southern Plains. A weak surface low may be in place across parts of northwest TX, and a dryline is forecast to mix eastward over portions of the southern High Plains through late Wednesday afternoon. ....Southern Plains... Thunderstorms may be ongoing at the start of the period Wednesday morning across parts of northern/central OK and vicinity. This convection will likely remain elevated and tied to modest low-level warm advection. While some hail risk may exist with this activity given ample MUCAPE forecast, the overall severe threat should remain rather isolated through the morning. A moist low-level airmass, with surface dewpoints generally in the mid to upper 60s, will continue advecting northward across the southern Plains through the day. Organized severe thunderstorm potential will likely remain confined by the cold front on the northern extent, and the eastward-mixing dryline across west TX. Diurnal heating of the moist warm sector, along with modestly steepened mid-level lapse rates, will aid in the development of moderate to locally strong instability from parts of west TX into southern/central OK and north TX. Most model guidance suggests MLCAPE of at least 2000-3000 J/kg will become increasingly prevalent across this region by late Wednesday afternoon. With the southern Plains forecast to remain on the southern extent of large-scale upper troughing, low-level flow (below 6 km) should remain fairly modest. But, mid/upper-level west-southwesterly winds should quickly strengthen with height to 90-110 kt around 250 mb. Corresponding deep-layer shear of 40-55 kt will easily support supercells with initial development along/south of the front and along/east of the dryline. Robust convection appears increasingly likely by early to mid Wednesday afternoon as parcels reach their LFCs. With moderate to strong buoyancy expected, somewhat steepened mid-level lapse rates, and long/generally straight hodographs forecast at mid/upper levels, isolated very large hail may occur with any supercells that can remain discrete. By late Wednesday afternoon or early evening, most guidance shows one or more thunderstorm clusters consolidating and sweeping east-southeastward across southern OK and into parts of north TX. Severe wind gusts will likely become the primary concern as this mode transition occurs, with isolated significant severe gusts possible where the greatest instability and steepened low-level lapse rates reside (western north TX vicinity into southwestern OK). Some strong/gusty wind risk should persist through Wednesday night across parts of north/central TX, but a gradually stabilizing boundary layer and increasing MLCIN should tend to limit the overall severe threat with southward extent into central TX. Based on recent trends in guidance, have expanded the Slight Risk to include more of OK and west/north TX. ...Gleason.. 10/03/2023 $$ = = = 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) .