Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Feb 12 2023 12:58:05 ACUS01 KWNS 121257 SWODY1 SPC AC 121256 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0656 AM CST Sun Feb 12 2023 Valid 121300Z - 131200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Isolated thunderstorms are possible through midday over the Tidewater region of North Carolina and southeastern Virginia, and late tonight in parts of Arizona. ....Synopsis... The mid/upper-level pattern over the CONUS is dominated by progressive but fairly low-amplitude northern stream from the northern Rockies to New England, and two similarly sized and deep cyclones to the south. The western low -- evident in moisture- channel imagery off southern CA -- is expected to pivot eastward across northern Baja this evening, reaching the YUM area by 12Z tomorrow. The associated circulation should maintain similar size and strength throughout the period, spreading cyclonic, difluent flow over the Desert Southwest in the process. Enough low/middle- level moist advection may underlie favorable cooling/lapse rates aloft to support isolated thunder very late tonight, across portions of western/southern AZ. Meanwhile, the eastern cyclone -- now centered over western/central GA -- will move east-northeastward over the Carolinas through this evening, centered near ILM by 00Z. It then should move offshore and shrink, as a strong northern-stream trough digs out of the Canadian Prairie Provinces to the Upper Great Lakes. Two surface lows are associated with this system: an occluded low analyzed at 11Z southwest of ATL near LGC, and a triple-point low moving northeastward just offshore from MYR. The latter will become the center of the principal surface cyclone, which should move east of HSE by 00Z, with cold front offshore from all the U.S. Atlantic Coast to its south. The low should be well offshore by 12Z, east of the Delmarva Peninsula and south of New England. ....Southern Outer Banks... At least a dozen small supercells have been evident for the past several hours in radar velocity imagery, over Atlantic waters south of the ILM-HSE coastal corridor. This includes a few ongoing northeast of the low and in the warm sector, merging with a band of offshore convection ahead of a midlevel dry slot that appears to be passing the ILM area currently. A couple of mini-supercells have approached the southern Outer Banks and dissipated in the process, while penetrating deeper into an extensive area of precip that is acting to maintain unfavorable boundary-layer stability. Continued northeasterly winds along the coastline, and associated cold trajectories relative to the offshore air, have maintained surface temperatures in the 50s over the beaches, though enough warm advection may occur to lead to low/mid 60s out by HSE. Regardless, the potential for a tornadic supercell to reach the coast has become too conditional and low to maintain an outlook area. ...Edwards.. 02/12/2023 $$ = = = 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) .