Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Dec 10 2022 12:39:38 ACUS01 KWNS 101239 SWODY1 SPC AC 101238 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0638 AM CST Sat Dec 10 2022 Valid 101300Z - 111200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THROUGH TONIGHT FROM WEST CENTRAL INTO EAST TX/WESTERN LA... ....SUMMARY... Isolated severe thunderstorms are possible through tonight from central TX to western Louisiana. ....TX and vicinity through tonight... In advance of a deep midlevel trough approaching the Pacific coast, a weakening southern stream shortwave trough will eject east-northeastward from Sonora toward central TX. At the surface, a cold front will move slowly southeastward across north TX and southern AR/northern LA by the end of the period. Rich low-level moisture is present along and south of the front, with boundary-layer dewpoints in the mid-upper 60s from central/north TX into LA this morning. Midlevel lapse rates exceed 7 C/km above the moist layer, and muted surface heating in cloud breaks will boost MLCAPE into the 500-1000 J/kg range by this afternoon along and south of the front. The convection this morning will remain elevated to the cool side of the front from OK eastward across AR/TN, with additional storm development expected closer to the front from west central into north TX by this afternoon. The weak-moderate buoyancy and effective bulk shear of 30-40 kt will be sufficient for some low-end supercell structures with an attendant threat for isolated large hail/damaging winds. Low-level flow/shear will remain rather weak through the period, but a brief/weak tornado may occur this evening into tonight as somewhat more discrete storms form along and just ahead of the front into southeast TX, coincident with the richest low-level moisture and the glancing influence of the Sonora midlevel trough. ....Northern/central CA through tonight... The primary baroclinic zone and forcing for ascent are approaching the northern CA coast this morning, with some weak/embedded mesovortex structures in a broken convective band. What limited buoyancy is present in this zone is likely rooted just above the surface, with the surface-based buoyancy increasing after frontal passage (when vertical shear will weaken). Farther inland, clouds will limit surface heating across the Sacramento and northern San Joaquin Valleys, and the colder midlevel temperatures/steeper lapse rates will not arrive until near or after local sunset. Isolated lightning flashes will be possible with low-topped convection through tonight, but the limited buoyancy and poor phasing with stronger vertical shear do not appear to warrant introduction of severe probabilities. ...Thompson/Leitman.. 12/10/2022 $$ = = = 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) .