Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Apr 21 2023 17:28:55 ACUS02 KWNS 211728 SWODY2 SPC AC 211727 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Fri Apr 21 2023 Valid 221200Z - 231200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM COASTAL SOUTH CAROLINA NORTHWARD INTO PARTS OF THE MID-ATLANTIC STATES... ....SUMMARY... Widely scattered severe storms are possible from parts of the Carolinas into the Mid Atlantic states Saturday afternoon and evening. Damaging gusts, large hail, and perhaps a brief tornado are possible. ....Synopsis... A negative-tilt upper trough will swing northeastward across the OH Valley and across the Appalachians during the day, with strong height falls into the Mid Atlantic by late afternoon or early evening. To the west, moderate west/northwest flow aloft will persist over the southern Plains with an upper ridge over the West. In the low levels, a surface low near Lake Erie Saturday morning will occlude as it moves northward into Ontario and southern Quebec. A trailing cold front will move east across the Carolinas, VA and PA during the afternoon. Ahead of the front, 50s F dewpoints will be common into PA and NJ, with 60+ dewpoints from southeast VA southward. Aiding moisture advection will be a 40+ kt low-level jet at 850 mb, which will also increase low-level shear. Elsewhere, moisture return will occur from Deep South TX up the Rio Grande Valley, reaching parts of central TX late as an east-west oriented cold front makes southward progress through the period. ....Carolinas/Mid Atlantic... A band of showers and isolated thunderstorms will likely be ongoing over the upper OH Valley extending southward into the southern Appalachians during the morning. Cloud breaks ahead of this precipitation will lead to a destabilizing airmass through early afternoon. Model guidance generally shows around 500 J/kg MLCAPE over VA to 1000-1500 J/kg farther south over the Carolinas. Effective shear supporting organized storms will promote organized multicells and perhaps a couple of transient/weaker supercells. The primary change from the previous outlook was to reduce severe probabilities over parts of GA/southern SC where the stronger forcing for ascent will become increasingly displaced from the region, and lower storm coverage is expected as a result. A few isolated strong to localized severe storms are possible over FL coincident with the diurnal heating cycle. The thunderstorm activity will likely weaken by early evening across FL and the severe risk will diminish as storms push east of the coast into the western Atlantic for areas farther north. ....Parts of central Texas... Little in the way of large-scale lift will exist over the area for much of the day as instability builds with heating and moisture advection. A plume of steep low-level lapse rates is forecast ahead of the front, and isolated storms will be possible after 00Z in the uncapped air mass and near the cold front. Long hodographs will favor hail in the stronger cells, and locally strong gusts. ...Smith.. 04/21/2023 $$ = = = 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) .