Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Mar 08 2024 05:36:17 ACUS01 KWNS 080536 SWODY1 SPC AC 080534 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1134 PM CST Thu Mar 07 2024 Valid 081200Z - 091200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY INTO TONIGHT ACROSS PARTS OF NORTHEASTERN TEXAS...SOUTHERN ARKANSAS...MUCH OF LOUISIANA...CENTRAL AND SOUTHERN MISSISSIPPI AND ALABAMA AND AN ADJACENT PORTION OF THE FLORIDA PANHANDLE... ....SUMMARY... Strong to severe thunderstorms may impact a corridor from parts of the southeastern Great Plains through the Gulf Coast states today through tonight. Some may be accompanied by potential for tornadoes, in addition to severe hail and wind, particularly across parts of southern into central Mississippi and Alabama late this afternoon into tonight. ....Synopsis... An amplified regime within a belt of westerlies emanating from the mid-latitude Pacific may continue to develop eastward through this period. This may include at least a short-lived evolution of a high center across the northern U.S. Intermountain region, within broader scale mid/upper ridging spreading inland of the Pacific coast through the eastern Canadian Prairies and portions of the northern U.S. Great Plains. Downstream of this ridging, significant troughing is forecast to dig across the Upper Midwest/upper Mississippi Valley vicinity, perhaps gradually beginning to come in phase with a lead impulse, within broad mid/upper troughing slowly emerging from the Southwest, before the end of the period. Substantive spread is evident within/among the various model output concerning this evolution, and model depictions of associated surface frontal wave development/cyclogenesis across and east of the Mississippi Valley are rather varied. A significant low-level cold intrusion to the lee of the Rockies is forecast to surge through the remainder of the southern Great Plains and northwest Gulf Coast vicinity today through tonight, while advancing a bit slower across/east of the middle Mississippi Valley and into the lower Mississippi Valley. It does appear that a more modest ongoing cold intrusion to the lee of the Appalachians will stall, with a frontal zone becoming better defined across the southern Piedmont by 12Z Saturday. A more substantive return of low-level moisture is ongoing across the northwestern Gulf of Mexico and northwestern Gulf coastal plain vicinity. This is likely to continue to advect northeastward, and may include surface dew points increasing to near 70F across and east of the lower Mississippi Valley. How far north and east will hinge on at least a couple of factors, including the impacts of outflow from persistent convective development forecast to spread east of the lower Mississippi Valley vicinity, and the extent of the development of a possible trailing surface low. Both of these remain uncertain, and could considerably impact the extent of the severe weather potential for this period. ....Gulf States... Convection rooted in ascent associated with lower/mid-tropospheric warm advection, near the northwestern periphery of low-amplitude subtropical ridging, may be ongoing at 12Z this morning across the lower Mississippi Valley, and persist through much of the period, gradually spreading eastward across the remainder of the Gulf into southern Atlantic Coast states. Substantive low-level moistening appears likely to follow in its wake, with trailing convective outflow at least initially limiting the northern extent of the better boundary-layer moistening. By mid to late afternoon, a zone of stronger differential surface heating may become best defined across parts of southwestern Alabama and south central Mississippi into northeastern Louisiana, near a developing surface low. Coupled with the boundary-layer moistening, weak to moderate CAPE (500-1000+ J/kg) may develop along this zone and contribute to the initiation of new thunderstorm development, in the presence of continuing low-level warm advection, beneath broadly difluent mid/upper flow. Beneath seasonably strong west-southwesterly mid/upper flow, the environment may become conducive to the evolution of sustained discrete supercells. Moderate southerly low-level flow across this region may also promote sizable clockwise curved low-level hodographs, with conditional potential for a strong tornado or two, depending on the evolution of the near surface thermodynamic profiles. It is possible that this activity could persist into the evening, and perhaps overnight, with a tendency for the lingering focusing surface boundary to develop east-northeastward across parts of southern into central Alabama and Georgia. Again much will depend on the upstream surface low evolution, which remains unclear. ...Kerr/Thornton.. 03/08/2024 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .