Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Feb 14 2023 17:30:12 ACUS02 KWNS 141730 SWODY2 SPC AC 141728 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CST Tue Feb 14 2023 Valid 151200Z - 161200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE LOWER MISSISSIPPI VALLEY...AND INTO PARTS NORTHEAST TEXAS AND SOUTHEAST OKLAHOMA... ....SUMMARY... Widely scattered severe thunderstorms are possible over parts of Texas and Oklahoma beginning late in the day and into the evening on Wednesday. A severe threat will also develop overnight over the lower Mississippi Valley, with tornado risk. ....Synopsis... An upper trough will become positively tilted as it moves east from the Four Corners to the Plains through Thursday morning, with an elongated speed max extending from the base of the trough from the southern Plains across the lower MO Valley and toward Lake Michigan late. Ahead of the trough, an upper high will remain over the Bahamas, with rising heights through 00Z across much of the Southeast. At the surface, low pressure will translate east from NM into OK through 00Z, ahead of a cold front which will surge south into the OK/TX Panhandles. This low is not forecast to deepen, but will continue northeastward ahead of the cold front to the Ozarks by 06Z and lower OH Valley by 12Z Thursday. Southerly surface winds will aid low-level moisture return during the day, with mid 60s F dewpoints common by 00Z over eastern TX and the lower MS Valley. Low 60s F dewpoints are eventually expected to reach the lower OH River/western KY by 12z Thursday, with the more substantial moisture from about Memphis south. Strengthening 850 mb winds over 40 kt will aid moisture transport, with modest instability and strong shear aiding severe potential from TX to the lower MS Valley, primarily after 00Z. ....Northeast TX...southeast OK into western AR... Heating will occur over OK and TX ahead of the cold front and south of the low, steepening lapse rates. Eventually, persistent southerly winds will bring low 60s F dewpoints to the Red River, most likely near or after 00Z. Modestly cool midlevel temperatures and convergence along the front may then be enough to break the cap, resulting in a few severe storms. Supercell wind profiles will exist, favoring large hail. Should the boundary layer moisten sufficiently, a tornado risk could develop. Much of this area appears conditional given mixed CAM signals, late moisture return, relatively late time of day (evening) and potential for capping. In addition, various forecast soundings indicate subsidence in the midlevels. However, stronger heating near the boundary coupled with late moisture return should result in at least isolated storms with hail. ....LA...MS...eastern AR...western TN... Rapid moistening of the boundary layer during the day is expected to lead to clouds and keep temperatures relatively cool. This should minimize the potential for convection through 00Z as a capping inversion will exist at or below 700 mb. Rain and thunderstorms are likely to develop after 03Z over much of AR, northern MS, and western TN, as dewpoints rise into the mid 60s F beneath a 50 kt low-level jet core. After about 06Z, a plume of > 1000 J/kg SBCAPE is forecast to extend from LA into eastern AR, gradually shifting into northwest MS and perhaps western TN. As such, it is possible that initially elevated convection transitions to surface based, which would increase the risk of isolated tornadoes. Better lift along the cold front could become a more favorable focus for supercells with tornado threat into Thursday morning. In general, the lack of a substantial baroclinic zone may mitigate the overall severe risk for much of the period, given cool boundary-layer temperatures. However, effective SRH near 300 m2/s2 will conditionally favor tornadoes with any established supercells that develop late near the MS River. ...Jewell.. 02/14/2023 $$ = = = 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) .