Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Nov 24 2022 19:48:34 ACUS01 KWNS 241948 SWODY1 SPC AC 241946 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0146 PM CST Thu Nov 24 2022 Valid 242000Z - 251200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL INTO COASTAL/SOUTHEAST TEXAS AND SOUTHERN LOUISIANA... ....SUMMARY... Strong thunderstorms may impact parts of central into southeast Texas and southern Louisiana through tonight. It is possible that a few of these could pose some risk for severe weather. ....20Z Update... Only minor changes have been made to the prior outlook. Ongoing elevated thunderstorms over central TX may continue to pose a threat for mainly small hail given fairly modest MUCAPE depicted by latest mesoanalysis. But, with strong deep-layer shear present and some steepening of mid-level lapse rates, the more robust cores may be capable of producing isolated marginally severe hail through this evening. An ongoing, loosely organized cluster of thunderstorms will move over the Houston metro area over the next couple of hours. While deep-layer shear is strong enough to support supercells, depictions of the low-level flow from recent KHGX VWPs show fairly weak winds and low-level shear in the 0-1 km layer. Still, isolated damaging winds and perhaps a brief tornado may occur along/near the TX Coast if this convection can strengthen this afternoon. An isolated threat for mainly strong/gusty winds will probably continue through the evening and overnight hours across parts of southern LA as a band of thunderstorms shifts eastward across this area. Weak instability should temper the overall severe threat. ...Gleason.. 11/24/2022 ..PREV DISCUSSION... /ISSUED 1020 AM CST Thu Nov 24 2022/ ....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. $$ = = = 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) .