Subj : DAY1SVR: Day 1 Convective To : All From : Mike Powell Date : Fri Jan 26 2024 08:55:00 ACUS01 KWNS 261249 SWODY1 SPC AC 261247 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0647 AM CST Fri Jan 26 2024 Valid 261300Z - 271200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Isolated strong thunderstorms are possible this afternoon over parts of west Texas, and tonight near the central Gulf Coast and over Louisiana. Organized severe weather appears improbable. ....Synopsis... The mid/upper-level pattern will remain progressive over the CONUS this period, with a trough now over CO and NM being the main convective influence aloft. This perturbation will house an intermittently closed 500-mb low -- initially over east-central/ northeastern NM. That low should move roughly eastward across the southern High Plains today, reaching the Caprock Escarpment between LBB-CDS around 00Z, then moving roughly down the Red River Valley to near I-35 in southern OK or extreme north-central TX by 12Z tomorrow. By that time, the positively tilted trough should extend from there southwestward to northern Coahuila. At the surface, a broad, wavy baroclinic zone was analyzed across the northern Gulf, modulated on the mesoscale by convective boundaries. This feature should shift north but still remain mostly offshore through the period, except for some warm-frontal incursion into the MS/AL/western FL Panhandle region possible near the end of the period. This would occur southeast of frontal-wave low development over the northwest Gulf, offshore from the TX Coast, in response to the approaching mid/upper trough. The low should move northeastward close to a LCH-JAN track overnight, with a synoptic warm front/inverted trough northeastward into the southern Appalachians. ....West TX... An organized thunderstorm or two may move southeastward across the southern South Plains and/or northern Permian Basin regions of west TX this afternoon, with potential for strong gusts and/or hail approaching severe limits. Though surface temperatures will remain cool over this region today (50s to low 60s in general), cooling aloft with the approaching trough will steepen low/middle-level lapse rates enough to support isolated strong convection, amid 30-40-kt effective-shear magnitudes. Inflow-layer parcels may even become briefly surface-based, depending on cloud breaks and insolation duration locally, with MLCAPE in the 300-700 J/kg range possible along the southern rim of the cold-core region. Lack of more-substantial inflow-layer moisture/buoyancy should preclude an organized/areal severe threat. ....Gulf Coast States... Strong convection is evident over open Gulf waters south of LA, in IR satellite pictures, lightning data and imagery from distantly located radar(s), with an extensive area of downstream anvil material and precip from that also being shown in radar composites. This precip may be under-depicted in composites, given the unavailability of the closest (former Slidell) radar while it is being relocated westward. This convection, being surface-based over a well-modified and relatively high-theta-e boundary layer, is likely to remain both organized and over the Gulf through the day and into much of tonight. Meanwhile, a relatively stable boundary layer to its north should be maintained and reinforced by: 1. Its own continuing downshear precip plume, and 2. Additional, widely scattered to scattered thunderstorms expected to form over east TX and LA from this afternoon through tonight, as elevated warm advection and moisture transport occur beneath steepening midlevel lapse rates overnight. Any sustained/discrete convection overnight in LA may produce hail with MUCAPE up to about 1500 J/kg and 40-50-kt effective-shear magnitude possible. However, with a lack of elevated MUCINH reasonably apparent in forecast soundings, storm mode may become clustered/messy fairly quickly. For now any severe-hail threat appears too conditional/isolated for probabilities. One area of interest for the last few hours of the period may be the coastal corridor around BIX-MOB-PNS, where theta-e advection may render surface-based parcels if earlier convection and related boundaries move away long enough beforehand. For now the predictability of such mesoscale processes remains too low to introduce unconditional severe probabilities, but this potential will be monitored through remaining outlook cycles. ...Edwards/Gleason.. 01/26/2024 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .