Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Sep 11 2023 05:47:39 ACUS01 KWNS 110547 SWODY1 SPC AC 110545 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CDT Mon Sep 11 2023 Valid 111200Z - 121200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHERN HIGH PLAINS... ....SUMMARY... Severe thunderstorms are possible over parts of eastern New Mexico into western and central Texas this afternoon and evening. Large hail and severe gusts are the main threats. ....Synopsis... A mid-level trough will amplify across the MS Valley while an embedded mid-level impulse traverses the Four Corners region and ejects into the southern Plains today. A surface cold front will continue to surge southward across the Southern Plains, bringing about cooler, stable air to the central U.S. However, ahead of the cold front, a surface low will develop and deepen across Far West Texas as the aforementioned mid-level impulse approaches. Surface low development will support a northwestward transport of low-level moisture beneath cooler temperatures aloft, resulting in adequate instability to support thunderstorm development. Stronger flow aloft from the approaching mid-level impulse will support strong vertical wind shear coinciding with the aforementioned instability across portions of the southern High Plains, resulting in a risk for severe thunderstorms. ....Portions of the southern High Plains... As the surface low deepens across Far West Texas during the day, low to mid 60s F surface dewpoints will advect northwestward toward the NM/TX border before the arrival of a southward-sagging cold front. Cloud cover and scattered showers will temper buoyancy across the warm sector to some degree through morning. However, stronger insolation is likely by afternoon, supporting surface temperatures over 90 F along and south of a west-east oriented baroclinic zone extending eastward ahead of the surface low. The boundary layer to south of the baroclinic zone should become deep and well mixed. 7-8 C/km mid-level lapse rates will overspread the warm sector during the afternoon, contributing to 2000-3000 J/kg SBCAPE. Westerly mid-level flow atop southerly low-level winds will support curved and elongated hodographs and corresponding 40+ kts of effective bulk shear. Storms are expected to form along the baroclinic zone, ahead of the surface cold front during the afternoon, with multicells and supercells the initial storm mode. Large hail and severe gusts are the main threats, though a tornado cannot be ruled out should a dominant supercell become anchored along the baroclinic zone, benefiting from locally higher streamwise vorticity. By evening, several of the storms should congeal into one or more southeastward-propagating MCSs, with severe winds becoming the dominant severe threat. ....Northeastern Florida Peninsula... Ample surface heating through the morning/early afternoon hours will boost surface temperatures to around 90 F amid 70+ F dewpoints, contributing to over 2000 J/kg SBCAPE despite mediocre mid-level lapse rates. Though tropospheric vertical wind profiles are not overly strong, enough low-level directional shear and upper-level speed shear may support the organization of multicellular clusters. Multicells will originate from storms initiating off of sea-breeze boundaries by afternoon. Water-loaded downdrafts will contribute to damaging gust potential with the stronger storms. ...Squitieri/Darrow.. 09/11/2023 $$ = = = 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) .