Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun May 21 2023 06:01:28 ACUS02 KWNS 210601 SWODY2 SPC AC 210600 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sun May 21 2023 Valid 221200Z - 231200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND SOUTHERN HIGH PLAINS AS WELL AS PORTIONS OF THE SOUTHEAST AND FLORIDA... ....SUMMARY... Isolated severe thunderstorms are possible across portions of the northern and southern High Plains as well as portions of the Southeast and Florida. ....Synopsis... A shortwave trough is expected to progress from the interior Pacific Northwest through the northern Rockies on Monday, as it rotates through the base of an upper low forecast to gradually move eastward over British Columbia. Weak upper flow is anticipated elsewhere throughout the CONUS, with upper ridging persisting over the northern/central Plains and broadly cyclonic flow over the Great Lakes and Northeast. Weak, nondescript upper flow is expected across the southern third of the CONUS. Surface pattern will likely feature expansive ridging across much of the eastern CONUS, with any low-level moisture relegated to the Southeast and southern Plains (on the southern/southwestern periphery of the ridging). Lee troughing is forecast to deepen throughout the day, contributing to modest southerly flow across the Plains. ....Southern High Plains... Southerly surface winds mentioned in the synopsis will result in modest moisture advection across the region, with dewpoints likely in the upper 50s and low 60s across the eastern TX Panhandle by Monday afternoon. Most guidance depicts a localized vorticity maximum (left from preceding thunderstorms) somewhere in the CO/OK/KS border vicinity. This MCV then contributes to a zone of southeasterly surface winds, increasing low-level convergence and supporting thunderstorm development. Additional storm development is anticipated across the higher terrain, and perhaps even the lee trough, farther west. Given the potential for multiple areas of development, overall convective evolution is uncertain. Initial supercells are possible over the eastern area, while high-based, outflow-dominant storms are more likely farther west. Any hail or tornado threat would likely be confined to the eastern area where supercells are possible. Damaging gusts are possible areawide. Some potential for upscale growth also exists, taking the threat for damaging winds into western OK and northwest TX. ....Northern High Plains... Thunderstorms are expected to develop over the northern Rockies amid increasing mid-level moisture and ascent attendant to the approaching shortwave trough. Moderate mid-level flow will be in place, contributing to some potential for hail with the initial development over the higher terrain. Storms will likely continue eastward into the lower elevations of central MT, where a well-mixed boundary layer will support strong outflow and the potential for a few severe gusts. ....Southern AL/GA and FL... Widespread thunderstorm development is expected across the region during the afternoon, fostered by ample low-level moisture, surface convergence (along a weak frontal zone and sea-breeze boundaries), and larger scale ascent attendant to a weak shortwave trough. A predominantly multicellular mode is anticipated, with generally brief storm lifecycles. However, vertical shear may be just strong enough for a few more organized storms capable of damaging downbursts. ...Mosier.. 05/21/2023 $$ = = = 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) .