Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed May 03 2023 17:18:31 ACUS02 KWNS 031718 SWODY2 SPC AC 031716 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1216 PM CDT Wed May 03 2023 Valid 041200Z - 051200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN PLAINS... ....SUMMARY... Severe thunderstorms capable of large hail, strong/damaging wind gusts, and a couple of tornadoes are possible across parts of the southern Great Plains Thursday afternoon and evening. ....TX/OK/KS... The upper ridge centered over the central/southern Plains will de-amplify on Wednesday as a series of shortwave impulses migrate through west/southwesterly flow. in response to modest height falls, a weak surface low is expected to develop over the western KS vicinity. A dryline will extend southward from the low across western OK into west-central TX. The day will begin with modest boundary-layer moisture across north TX into OK/KS. However, southerly low-level flow will transport a somewhat narrow corridor of low 60s F dewpoints northward across OK/KS through early evening. Deeper boundary-layer moisture will reside further south across central/southern TX where mid/upper 60s F dewpoints are expected. Uncertainty in convective initiation/evolution remains, especially from north TX into KS. A few scenarios are possible, with one point of uncertainty being potentially early ejection of a lead shortwave impulse around midday. If convection develops early in the afternoon, tied to the early shortwave impulse, elevated storms will be more likely. However, some guidance suggests decaying overnight convection and morning cloudiness over OK and vicinity could suppress early CI from the lead shortwave impulse. If this occurs, there may be better potential for late afternoon surface-based convection along the dryline in OK/southern KS. While this leads to a more uncertain/conditional forecast, a moist boundary-layer beneath steep lapse rates will support moderate destabilization. Furthermore, the nose of the midlevel jet will overspread the region during the afternoon and vertically veering profiles will result in 40+ kt effective shear. Supercells will a risk of large hail and strong gusts will be possible. If surface-based afternoon storms develop near the dryline bulge across northwest OK into south-central KS, backed low-level winds and effective SRH increasing to around 250 m2/s2 will support potential for a couple of tornadoes. Further south along the dryline in central TX, strong heating and mid/upper 60s F dewpoints will support MLCAPE values to around 2000-3000 J/kg by afternoon. Low to mid-level flow will be somewhat weak, but rapidly increase with height above 700 mb. Sufficient veering with height also will contribute to effective shear values greater than 40 kt. Supercells capable of large hail (some greater than 2 inches in diameter) will be possible. Given steep low-level lapse rates to around 850 mb and weak low-level winds, strong outflow and storm interactions may support some upward development into forward-propagating clusters by early evening. Damaging gusts in addition to large hail will be possible with this activity. ....Nebraska vicinity... Boundary-layer moisture will remain modest with northward extent into NE. However, steep midlevel lapse rates will support modest destabilization as temperatures warm to near 80 F ahead of a southward-progressing cold front. Modest deep-layer flow will limit longevity/better-organized updrafts, but marginally severe hail and strong gusts will be possible with more intense convection. ....Great Basin/Northwest... Scattered thunderstorms are expected in increasing southwesterly flow on the eastern periphery of the CA/NV upper low, and in the easterly flow regime on the north side of the low across ID toward the Cascades. Limited moisture and a deeply-mixed boundary-layer will result in high-based convection. Steep lapse rates will aid in modest destabilization with gusty winds and small hail possible. ...Leitman.. 05/03/2023 $$ = = = 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) .