Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Apr 30 2023 05:54:06 ACUS01 KWNS 300554 SWODY1 SPC AC 300552 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Sun Apr 30 2023 Valid 301200Z - 011200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CAROLINAS AND MID ATLANTIC AS WELL AS INTO CENTRAL AND SOUTHERN FLORIDA... ....SUMMARY... Severe thunderstorms will be possible across parts of the Carolinas into the Mid Atlantic, and also across parts of central and south Florida. Damaging winds and a few tornadoes will be the primary hazards, though isolated hail will also be possible. ....Synopsis... In the mid levels, 00z RAOB data showed an incipient omega block developing over the west-central CONUS with a broad cyclone over the eastern Great Lakes occupying the eastern node of the block. To the south of the closed low, a southern stream shortwave trough and accompanying jet streak were observed along the upper Gulf Coast. The shortwave and jet streak are forecast to move north across Southern and Mid Atlantic Seaboard through the day with an accompanying surface cyclone and trailing cold front. As the front and low move eastward, strong lift and deep moisture will support thunderstorm development ahead of the front from the Carolinas, southward across FL, before shifting offshore. By early evening, the deepening upper cyclone should absorb the shortwave as the omega block becomes established across much of the CONUS, and a second cold front crosses the Appalachians. ....Carolinas to the southern Mid Atlantic... By 12z, the sub-1000mb surface low should be located near the middle NC/SC border with the cold front tailing south over the western Piedmont. Widespread rain and cloud cover are expected over the Carolinas in the wake of previous day's convection. Pockets of insolation may support MLCAPE near 1000 J/kg given surface dewpoints the mid 60s F. Scattered thunderstorms are expected to form early in the morning and persist through midday ahead of the cold front. Strong meridional flow will support elongated, but mostly straight hodographs. Several bands or clusters of linear storms and a few supercells will likely organize with a risk for damaging wind gusts. A couple tornadoes will also be possible given enhancement of the low-level shear by a 40-50 kt low-level jet. As the surface low lifts northeastward through the morning, strong southerly low-level flow will quickly veer as the front sweeps eastward. Storms will shift northward into the Mid Atlantic by late morning and early afternoon. Strong vertical shear will remain in place as the shortwave and jet streak lift northward, supporting a continued risk for damaging gusts and perhaps a tornado. However, much weaker buoyancy is expected with northward extent, owing to weaker insolation and the northern limit of deeper surface moisture over southern VA with surface dewpoints in the upper 50s to low 60s F. Storms should gradually weaken through the late afternoon and early evening, as they cross into the cooler and more stable air mass. The cold front and surface low should finally move offshore early in the evening, ending the severe threat. Isolated severe storms may also develop in the lee of the central Appalachians across western NC/SC and VA ahead of the second polar front moving eastward. Confidence in severe coverage here is much lower owing to weaker buoyancy from previous convection and veered surface flow. Strong mid-level westerlies may still support the risk for a few damaging wind gusts with marginally organized short line segments or multicell clusters through the afternoon. ....South Florida... Along the southern end of the front, moist inland flow is expected through the morning hours across portions of South FL. Frontal forcing should support scattered to numerous thunderstorms from early to mid morning as the front moves southeast. Mid 70s F surface dewpoints and modest mid-level lapse rates near 6 C/km will support inhibition-free, 1500-2000 J/kg of MLCAPE early in the day. 50-60 kt of 500mb flow behind the departing shortwave will linger over the southern peninsula, supporting elongated hodographs and sufficient mid-level shear for storm organization. Short linear segments and or supercell structures may evolve with a risk for damaging gusts and isolated hail ahead of the front. A few tornadoes are also possible with any sustained supercells. Though low-level shear will be strongest early in the period before it gradually weakens through the day as low-level flow veers along the front. Storms should continue to move east/southeast with a risk for wind and hail through the early afternoon. The severe risk should end by late afternoon/early evening as storms and the front move completely offshore by 20-22z. ...Lyons/Kerr.. 04/30/2023 $$ = = = 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) .