Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Feb 15 2023 19:29:03 ACUS01 KWNS 151928 SWODY1 SPC AC 151927 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0127 PM CST Wed Feb 15 2023 Valid 152000Z - 161200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN ARKANSAS INTO WESTERN TENNESSEE AND NORTHERN MISSISSIPPI... ....SUMMARY... Severe thunderstorms with large hail are possible over parts of north Texas and southern Oklahoma this afternoon and evening. A threat for tornadoes, severe-thunderstorm winds and isolated hail will also develop overnight over the lower Mississippi Valley/Mid-South region. Little change was made to the previous outlook. Low-level moisture continues to increase across the southern Plains, although total precipitable water values remain quite low with the northern portion of the 50+ F dewpoints plume. Eventually, strong heating and continued moisture advection will lead to an uncapped air mass with scattered storms developing over western north TX into southern OK. Large hail will be the main concern, mainly after 00Z. Overnight, a tornado threat is expected to develop over eastern AR, northern MS, and western TN, beneath a strong low-level jet and with access to an instability plume extending southwest through the ArkLaTex. Effective SRH near 300 m2/s2 and MLCAPE over 1500 J/kg may support a strong tornado or two. ...Jewell.. 02/15/2023 ..PREV DISCUSSION... /ISSUED 1032 AM CST Wed Feb 15 2023/ ....Synopsis... A closed upper low and attendant shortwave trough located over the Four Corners this morning will continue to shift east toward the southern Rockies and adjacent central/southern Plains through tonight. A lead shortwave impulse was noted in 15z water vapor imagery as of 15z ejecting over the southern Rockies in NM into the southern High Plains. Increasing ascent and a strengthening low-level jet associated with this feature will drive convective initiation by late afternoon/early evening across northern TX/southern OK. At the surface, strengthening cyclogenesis is expected to ensue over the next few hours across the southern High Plains. As this occurs, increasing southerly low-level flow will continue to transport Gulf moisture northward across the eastern half of TX into southeast OK, and eastward across the Lower MS Valley. A sharpening dryline/Pacific front oriented north to south from south-central OK into central TX, and a warm front lifting north of the Red River will focus initial thunderstorm development in the 21-00z time frame. ....Southern OK/Northern TX... Most guidance, including CAMs, initially develops supercells near the I-35 corridor in south-central OK/north TX in the 21-00z time frame. Modified forecast soundings for expected afternoon dewpoints near 60 F and temperatures in the mid/upper 70s indicate strong MUCAPE around 1500-2500 J/kg. Much of this instability is focused in the mid and upper levels of the sounding profile. Rapidly increasing and vertically veering winds with height are producing enlarged low-level hodographs, becoming elongated above 3 km. This thermodynamic and kinematic profile will favor initial supercell development. Furthermore, many significant hail sounding analogs are noted and hail in excess of 2 inches in diameter appears possible early in thunderstorm evolution. Deeper low-level moisture and a more established warm sector will remain somewhat east of this area. As a result, initial thunderstorms may have a higher LCL with some low-level dryness above the surface to around 1-1.5 km. This could enhance downdraft strength and also result in isolated to widely scattered damaging gusts as well. As a low-level jet increases after 00z, SRH values are forecast to increase from around 150 m2/s2 to over 250 m2/s2 and low-level moistening will increase with eastward extent. At this point, any semi-discrete convection will likely become more linear. Nevertheless, strong low-level shear and favorable 0-3 km hodographs will support rotation within embedded cells and mesovortices. ....Arklatex/East TX, to TN Valley/Mid-South... The severe threat will shift east across the Arklatex vicinity toward the Mid-South this evening into the overnight hours. Damaging gusts, isolated large hail, and tornadoes (a couple EF-2+ in strength) are expected. A more conditional severe threat will exist this afternoon/early evening across east TX into southern/central LA. Large-scale ascent will remain weaker across this area, and the surface front will remain well east of this area until late in the period. However, a quality warm sector will reside across this area with mid to upper 60s surface dewpoints expected. Low-level confluence and some influence on the margins of strong low/midlevel flow could support the development of a supercell or two. If this occurs, all severe hazards will be possible. However, this scenario remains uncertain and too conditional and will maintain a categorical Slight risk. Between 03-06z a southwesterly low-level jet will increase to 50-60 kt and overspread AR into northern MS and western TN, and eventually into KY and vicinity by 12z Thursday. Multiple bands/clusters of thunderstorms will be possible in low-level confluence within the northward developing low-level moisture plume. Embedded supercells will offer all severe hazards. The most favorable overlap of rich boundary-layer moisture and favorable low-level hodographs and SRH will exist across eastern AR into northwest MS/western TN vicinity after 00z. The tornado threat will be greatest across this area, with environmental parameter supporting the potential for a couple of significant tornadoes (EF-2+ intensity) in addition to damaging gusts. With northward extent, instability will become less toward western KY and vicinity later tonight. Nevertheless, strong shear and sufficient instability will support damaging wind potential into early Thursday morning. $$ = = = 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) .