Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Nov 24 2022 16:22:02 ACUS01 KWNS 241621 SWODY1 SPC AC 241620 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1020 AM CST Thu Nov 24 2022 Valid 241630Z - 251200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY THROUGH TONIGHT ACROSS THE MID AND UPPER TEXAS INTO SOUTHERN LOUISIANA COASTAL PLAIN...AND PERHAPS PARTS OF CENTRAL TEXAS... ....SUMMARY... Strong thunderstorms may impact parts of central and southeastern Texas into southern Louisiana today into tonight. It is possible that a few of these could pose some risk for severe weather. ....Synopsis... The westerlies appear to be trending more progressive across the northern mid-latitudes of the Pacific through North America, while remaining more amplified in the southern mid- and subtropical latitudes. The latter regime still includes prominent ridging along an axis from the subtropical eastern Pacific into the Pacific Coast states, with a significant downstream low digging along the higher terrain of New Mexico. Models suggest that the mid-level low will continue southward into northern Chihuahua through late tonight, while mid-level ridging develops eastward across and east of the northern Rockies, and downstream short wave troughing digs across the Upper Midwest and Great Lakes region. In lower levels, expansive cold surface ridging is in the process of shifting off the Atlantic Seaboard, but potentially cold air associated with it still lingers across much of the Southeast, and as far southwest as Louisiana/adjacent southeast Texas coastal areas. Only a gradual further modification is forecast, with a reinforcing intrusion of cold air already surging southeast of the Rockies, as far south as the Texas/Oklahoma Panhandle vicinity. As this air spreads across the southern Great Plains toward northwestern Gulf coastal areas, potential for surface cyclogenesis likely will remain suppressed to the lee of the southern Rockies. ....Texas/Louisiana... Sufficient low-level warming and moistening has occurred, in association with southerly return flow around the southwestern periphery of the retreating surface ridge, to contribute to sufficient destabilization for increasing thunderstorm development. Initially, this has been mostly rooted within a lower/mid tropospheric warm advection regime across central through northeastern Texas, above a residual near-surface stable layer. However, this stable layer has become increasingly shallow in a corridor across parts of the Edwards Plateau and Hill Country into the mid/upper Texas coastal plain. In advance of the digging mid-level low, a belt of westerlies emanating from the subtropical eastern Pacific has become increasingly cyclonic across and east of the lower Rio Grande Valley, with some building of downstream ridging across the lower Mississippi Valley into the Southeast. This will generally be maintained through this period, but a smaller-scale short wave perturbation is in the process of progressing through this regime, and may be contributing to recent thunderstorm initiation across parts of Deep South Texas into the upper Texas coastal plain. It appears that this activity will increase in coverage through the day, before spreading into/through the lower Mississippi Valley overnight. This convection will at least inhibit further near-surface destabilization inland of mid/upper Texas coastal areas, if not tend to stabilize the environment, but modest boundary-layer destabilization (CAPE on the order of 500-1000 J/kg) still appears possible near immediate coastal areas. In the presence of strong deep-layer shear (beneath 50+ southwesterly 500 mb flow), any convection supported by inflow of this unstable boundary-layer air may tend to gradually organize. While this could eventually include a couple of supercell structures, the tendency for low-level flow to remain modest or weaken and veer through the day will maintain smallish low-level hodographs and limit the overall severe weather potential. ...Kerr/Thornton.. 11/24/2022 $$ = = = 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) .