Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Mar 25 2024 05:50:12 ACUS01 KWNS 250550 SWODY1 SPC AC 250548 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Mon Mar 25 2024 Valid 251200Z - 261200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF EXTREME SOUTHEAST ARKANSAS INTO NORTHEAST LOUISIANA AND CENTRAL MISSISSIPPI... ....SUMMARY... Severe thunderstorms with a threat for tornadoes and damaging winds are possible today through tonight from parts of east Texas through the Lower Mississippi Valley. An instance of hail or a brief tornado also cannot be ruled out over parts of the Midwest. ....Synopsis... A mid-level trough will traverse the central U.S. while progressing eastward and taking on a negative tilt. During the day, a 100+ kt 500 mb jet streak will overspread the central MS Valley as a 994 mb surface low tracks from the central Plains toward the Great Lakes. Deep-layer ascent and strong vertical wind shear ahead of the mid-level trough/surface low will support strong thunderstorm development along or immediately ahead of an eastward-advancing Pacific front. Storms should mature over the Mid-South during the afternoon and progress toward the Gulf Coast states by evening. Given adequate low-level moisture and overall buoyancy over the Mid-South, severe thunderstorms are possible. Closer to the surface low, and where temperatures are coldest aloft, an isolated severe threat may materialize, particularly over portions of the Midwest. ....Mid South toward the Gulf Coast Region... Thunderstorms should be ongoing along or immediately ahead of the Pacific front at the start of the period over portions of central or eastern TX. Despite widespread cloud cover likely over the entire warm sector, strong low-level warm-air/moisture advection (driven primarily by a 60+ kt southerly 850 mb jet) will contribute to a moistening boundary layer, as cooler temperatures aloft graze the Mid-South from the north and west. Mid 60s F dewpoints, overspread by 6-7.5 C/km mid-level lapse rates, will boost SBCAPE into the 500-1000 J/kg range by afternoon peak heating across portions of extreme eastern TX and LA into southern and central MS. Here, the overlapping of the intense low-level and mid-level jets will support rapidly veering/strengthening vertical wind profiles, contributing to sizeable clockwise-curved low-level hodographs with mid-level elongation. Effective SRH exceeding 400 m2/s2 will support the development of strong mesovortices embedded within a squall line. Damaging gusts and QLCS tornadoes are possible, especially over eastern LA into southern and central MS, where the best overlap of SRH and adequate surface-based buoyancy should precede a well-organized QLCS. A few strong tornadoes are also possible given the very strong low-level shear. Otherwise, the squall line should progress eastward into AL with an isolated damaging gust/tornado threat, though the severe threat should begin to wane sometime between 09-12Z as the line outpaces the warm sector. ....Portions of the Midwest... Near the surface low, very cold temperatures aloft will support 8+ C/km mid-level lapse rates beneath 60 F surface dewpoints, boosting SBCAPE to over 500 J/kg by late morning or early afternoon. Strong deep-layer ascent will support the development of several thunderstorms amid deep-layer southerly flow. Speed shear will contribute to elongated hodographs, and when considering the colder temperatures aloft, a couple instances of severe hail may accompany multicellular clusters. Furthermore, strong low-level convergence north of the surface low, in the vicinity of abundant surface vertical vorticity, may result in the development of a landspout or two with one of the stronger multicells as well. ...Squitieri/Darrow.. 03/25/2024 $$ = = = 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) .