Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jun 21 2023 06:03:51 ACUS01 KWNS 210603 SWODY1 SPC AC 210602 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0102 AM CDT Wed Jun 21 2023 Valid 211200Z - 221200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL HIGH PLAINS INTO THE SOUTHERN PLAINS... ....SUMMARY... Isolated to scattered severe thunderstorms are possible on Wednesday across portions of the Plains. Large hail and severe gusts will be the main hazards with this activity. Isolated strong storms also will be possible across parts of the Southeast, with an accompanying risk for damaging gusts. ...Central High Plains... Near the northeastern Colorado/southeastern Wyoming intersection of the northern Plains cold front and the trailing/High Plains segment of the southern U.S. front, afternoon thunderstorm development is expected. This anticipated initiation will occur as an unusually moist boundary layer heats through the afternoon, resulting in 2500 to 3500 J/kg mixed-layer CAPE. While mid-level southwesterly flow is not progged to be particularly strong, low-level southeasterlies veering with height will provide sufficient shear (given the very favorable thermodynamic environment) to support organized/supercell storms. Potential for isolated instances of very large hail, and a few strong/damaging wind gusts, will be possible, along with potential for a couple of tornadoes. Risk should gradually diminish across southeastern Wyoming and the Nebraska Panhandle into the later evening hours, though some CAMs suggest potential for evening storm initiation over east-central/southeastern Colorado, with upscale growth into a south-southeastward/moving MCS possible. A few strong wind gusts would be possible in this scenario. ....Southern Plains... Substantial uncertainty exists with respect to convective initiation potential near the dryline, across eastern portions of the Texas Panhandle/south Plains area. From a large-scale perspective, a very moist but capped boundary layer will likely be maintained into the afternoon given presence of short-wave ridging aloft. Atop the cap, very steep lapse rates will support extreme CAPE -- in excess of 5000 J/kg. Meanwhile, with moderate westerly mid-level flow across this area atop low-level east-southeasterlies, shear would support rotating storms -- particularly given the thermodynamic environment. Given the cap, some CAM runs (particularly the HRRR) limit development to a couple of late-afternoon, isolated supercells. Given conditional/background risk for giant hail and strong/damaging wind gusts, any storm that does develop would be capable of producing significant severe weather. Other CAM runs however, are much more aggressive/widespread with respect to convective development/coverage, primarily those which develop convection over the central Plains prior to the start of the period, and shifts into Oklahoma early in the period. As remnant outflow spreads west-southwestward across Oklahoma toward the Texas Panhandle through the day, and eventually interacts with the dryline, much more widespread storm development occurs. With time, these more aggressive CAMs then shift a developing MCS southeastward across central Texas during the evening, with some severe risk extending as far southeastward as the Texas Coastal Plain overnight. While this scenario remains conditional/uncertain, will maintain 15% hail/wind (SLGT risk) across eastern portions of the Texas and Oklahoma Panhandles and into the Texas South Plains and western North Texas. ....Florida... Episodes of convection will affect parts of Florida today and tonight, on the southern periphery of the southern Appalachians upper cyclone. The most widespread of the thunderstorm activity will likely exist from late morning through late afternoon, with bands of storms spreading eastward from the eastern Gulf across central portions of the Peninsula. With moderate west-southwesterly flow aloft forecast across the area, stronger storms/bands of storms will likely produce gusty winds, locally near or exceeding severe levels. ...Goss/Wendt.. 06/21/2023 $$ = = = 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) .