Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Dec 17 2022 12:29:09 ACUS01 KWNS 171229 SWODY1 SPC AC 171227 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0627 AM CST Sat Dec 17 2022 Valid 171300Z - 181200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Thunderstorms are possible today over parts of south Florida and the Keys. Organized severe weather appears unlikely. ....Synopsis/Discussion... In mid/upper levels, a deep/stacked cyclone -- centered initially over northern WI -- is forecast to move erratically eastward across the Upper Great Lakes through the period, reaching the neck of ON by 12Z tomorrow. Fast, nearly zonal flow aloft is apparent in satellite imagery well to its south, across the Gulf Coast and southern Atlantic Coast States. This flow belt is downstream from a positively tilted shortwave trough -- evident in moisture-channel imagery from southeastern MO across southern OK to far west TX. This trough will race eastward today, reaching a position from the Delmarva Peninsula across northern GA to southern MS by 00Z, and entirely offshore from the Atlantic Coast shortly after 06Z. In response to these developments, a stalled surface front initially over the Straits of Florida, very near the Keys, should move slightly northward as a warm front today, ahead of a weak frontal- wave low moving eastward from the central Gulf. This will spread a more-favorable, maritime/tropical boundary layer (with 70s F surface dewpoints) back into parts of south FL, conterminous with gradual/ modest diabatic surface heating, under considerable cloud cover. Accordingly boosted boundary-layer theta-e should support overland MLCAPE in the 1000-1500 J/kg range, beneath sufficiently strong mid/upper winds for 35-40-kt effective-shear magnitudes. General thunderstorm potential exists very near and south of the front across much of south FL and the Keys. Isolated strong thunderstorms may develop this afternoon, especially along the eastern parts of the front and/or sea-breeze boundary very near the immediate Atlantic coastline, then move offshore. However, overall organization and severe potential will be minimized by a combination of midlevel stable layer(s) and weak low-level flow (limiting boundary-layer shear and hodograph size). ...Edwards/Kerr.. 12/17/2022 $$ = = = 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) .