Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jun 03 2023 19:38:57 ACUS01 KWNS 031938 SWODY1 SPC AC 031937 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0237 PM CDT Sat Jun 03 2023 Valid 032000Z - 041200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER RIO GRANDE VALLEY IN SOUTH TX... ....SUMMARY... A swath of severe wind gusts may occur between about 8 PM to Midnight CDT along a portion of the Lower Rio Grande Valley. Otherwise, isolated severe thunderstorms with wind and hail will be possible across parts of the south-central and northeastern states, mainly through this evening. ....20Z Update... ....Far eastern NM to South TX... Thunderstorm initiation has already occurred across the higher terrain, with deepening cumulus along the lee trough as well. Expectation is for these storms to move eastward over time, posing a threat for isolated severe gusts and perhaps a few instances of hail. Cumulus is deepening just south of SJT as well, along a remnant outflow boundary. Continued development is anticipated, with scattered thunderstorm coverage likely by the late afternoon. Shear is limited, but strong buoyancy is in place, supporting the potential for robust updrafts capable of hail and damaging gusts. ....Lower Rio Grande Valley... Conditional scenario outlined in the previous discussion still appears plausible this evening and overnight, with recent CAM solutions contributing to its validity. Expectation is for persistent development over the higher terrain of Coahuila to eventually move eastward as an MCS. This supports continuing the 15% wind across the RGV. ....Mid-Atlantic/Central Appalachians/Upper OH Valley... Thunderstorms initiated a few hours ago along a southward/southwestward progressing cold front moving through central PA. A few stronger storms are possible within the eastern periphery of this region, particularly eastern PA, where slightly stronger flow overlays the unstable airmass. Mesoanalysis indicates effective shear of 30-40 kt across this region. Flow weakens with westward extent and storms will tend to be more disorganized within this weakly sheared environment. Even so, sufficient buoyancy and steep low-level lapse rates may support localized downbursts and small to briefly severe hail. ....Arklatex to Southern LA... As mentioned in MCD #931, a Marginal risk for hail and gusty winds remains through the afternoon from the Arklatex into southern LA. Moderate buoyancy is in place, but weak shear should limit storm organization and strength. Isolated gusty winds and hail are the primary severe threat. ...Mosier.. 06/03/2023 ..PREV DISCUSSION... /ISSUED 1125 AM CDT Sat Jun 03 2023/ ....Far eastern NM to south TX... An elongated, low-amplitude upper trough will stay anchored from the Great Basin to the southern High Plains through tonight. The attendant belt of moderate mid-level westerlies will largely remain confined across northern Mexico into Deep South TX. Several areas of isolated to scattered thunderstorm development are expected later this afternoon into the evening: 1) the higher terrain of northern Coahuila into perhaps the Big Bend, 2) a remnant outflow boundary over the Concho Valley, and 3) the far eastern NM/west TX border area from the Raton Mesa to the Permian Basin. Areas to the north of south TX will be in a more modest deep-layer shear environment with effective values around 20-30 kt. This should generally support weak and transient mid-level updraft rotation and multicell clustering. Owing to continued steep mid-level lapse rates, large hail and severe wind gusts will be possible with overall coverage expected to remain isolated. A relatively greater but largely conditional severe threat may occur over a portion of the Rio Grande Valley in south TX later this evening if supercell clusters over Coahuila can develop an adequate cold pool prior to the nocturnal increase in MLCIN. The 14Z HRRR is the most insistent of morning CAMs with its depiction of an MCS moving east of the international border. Guidance is fairly consistent that negative low-level theta-e advection will shift west from the northwest Gulf across Deep South TX tonight, likely yielding weakening of convection as it spreads farther east of the Rio Grande. ....Mid-Atlantic/Central Appalachians/Upper OH Valley... Isolated to scattered thunderstorms should develop along a west to southwest-moving cold front, with initial development expected in PA based on a swelling cu field already. A pocket of moderate buoyancy with MLCAPE of 1000-1500 J/kg will similarly form just ahead of this portion of the front. Guidance suggests there may be a belt of somewhat greater north-northeasterly mid-level winds in the eastern PA vicinity. But the lack of a 12Z ALB observed sounding or VWP data high enough to sample this lowers overall confidence. CAM guidance does suggest that a couple of southwest-moving cells that initiate in this region may contain mid-level updraft rotation which could result in a meso-beta corridor of relatively greater hail and wind potential. Elsewhere, weaker deep-layer shear and buoyancy will serve to limit potential to locally strong gusts from sporadic microbursts amid steep low-level lapse rates and a relatively deep mixed boundary layer. ....Ark-La-Tex to south LA... Scattered to widespread thunderstorms are expected later this afternoon within a moderately buoyant and weakly sheared environment. The strongest storms will be capable of locally strong wind gusts. $$ = = = 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) .