Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Feb 07 2023 12:53:06 ACUS01 KWNS 071253 SWODY1 SPC AC 071251 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0651 AM CST Tue Feb 07 2023 Valid 071300Z - 081200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHEAST TEXAS... ....SUMMARY... Isolated strong to severe thunderstorms are possible this evening and overnight across portions of southeast Texas. ....Synopsis... The mid/upper-level pattern over the CONUS is dominated by a positively tilted trough in the process of splitting. The northern-stream segment -- initially located from Lake Superior across the upper Mississippi Valley to eastern NE and northern KS -- will move quickly eastward across the Great Lakes, Ohio Valley, Mid-Atlantic and New England through the period, while gradually weakening. The southern part -- apparent in moisture-channel imagery over CO, northwestern NM and AZ -- is developing a closed low near the central NM/AZ line. The 500-mb low should pivot/ redevelop southward today, turn eastward across southern NM this evening, then pivot northeastward overnight. By 12Z tomorrow, the southwest/northeast-elongated cyclone's center should cross the Llano Estacado in the area between LBB-TCC, with troughing from southwestern KS to southern Chihuahua. At the surface, 11Z analysis showed a wavy cold front -- nearly stationary in a few places -- from near STL across northwestern AR, southeastern OK, western north TX, the Edwards Plateau, and the lower Pecos Valley of southwest TX. By 00Z, the front should extend from central/western AR across northeast TX, through a frontal wave near DAL, then southwestward near and parallel to the curve of the Balcones Escarpment, to near DRT. By 12Z, the frontal wave should evolve into a closed surface low over northeast TX between PRX-TXK, with cold front across east TX to near VCT, to the Rio Grande Valley between LRD-MFE. ....Southeast TX... Widely scattered to scattered prefrontal thunderstorms are expected to develop and gradually expand in coverage tonight over parts of the middle TX Coastal Plain, expanding inland and eastward with time into southeast TX. Isolated, marginally severe gusts are possible, and a conditional/brief tornado potential may develop as well. Substantial height falls and DCVA will lag the cold front, leaving warm advection and the front itself as the primary sources of lift across the outlook area. Return flow will mature gradually through the period following the early stages of marine airmass modification, resulting in a field of 60s F surface dewpoints but modest low-level lapse rates across the region. Though forecast soundings yield effectively surface-based lifted parcel calculations, a shallow, near-surface stable layer is apparent. This is reasonable, given the late nocturnal cycle, and likely presence of precip over some of the area. Still, MLCAPE to near 1000 J/kg may develop, amidst well-curved, LLJ-enlarged hodographs, with 150-300 J/kg effective SRH, and modest deep shear (effective- shear magnitudes only about 30-35 kt). Lack of greater deep shear and near-surface instability, and of more sharply focused lift, preclude more than a marginal severe threat before 12Z. ...Edwards/Leitman.. 02/07/2023 $$ = = = 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) .