SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CDT Tue Oct 25 2022 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF WESTERN TENNESSEE INTO MISSISSIPPI AND CENTRAL ALABAMA... ...SUMMARY... Strong to severe thunderstorms are likely from the Lower Mississippi Valley into the Southeast States today. Damaging gusts and tornadoes will be possible. ...Synopsis... A negatively tilted mid-level shortwave trough will progress across the Lower Mississippi Valley as a 1002 mb surface low tracks from northern Arkansas to the Ohio Valley today. Adequate moisture and associated instability will advect ahead of the surface low across portions of the Southeast into the Tennessee Valley to support scattered to widespread strong thunderstorms. An organized severe threat may materialize across the Southeast where the stronger buoyancy and shear are expected to overlap. ...Portions of the Southeast into the TN Valley... Widespread clouds and precipitation are expected to precede the surface low and cold front at the start of the period. While the overall lack of insolation will hamper more robust buoyancy from materializing, mid to upper 60s F dewpoints should advect northward to the TN border through the afternoon, promoting 500-1000 J/kg of tall, thin MLCAPE (given 6 C/km mid-level lapse rates). Buoyancy should diminish with northward extent toward the OH Valley. A squall line should be ongoing at the start of the period across the Mid-South and is poised to move into a more unstable airmass across MS, AL and southwest TN by afternoon. In these areas, forecast soundings depict impressively sheared vertical profiles, characterized by long, largely curved hodographs with well over 50 kts of effective bulk shear and 300-500 m2/s2 of effective SRH. As storms intensify within the squall line, QLCS mesovortices may develop, with tornadoes and severe gusts being the main concerns. Farther north into Middle TN and points northward, scant buoyancy should limit the severe threat to a sparse damaging gust and perhaps a brief tornado. ..Squitieri/Darrow.. 10/25/2022
