Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Mar 28 2023 07:19:38 ACUS03 KWNS 280719 SWODY3 SPC AC 280718 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0218 AM CDT Tue Mar 28 2023 Valid 301200Z - 311200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND EASTERN NEBRASKA...AND PARTS OF OKLAHOMA INTO NORTHERN TEXAS... ....SUMMARY... Isolated strong storms may produce hail across parts of central/eastern Nebraska Thursday evening. A more conditional threat for severe thunderstorms will exist late Thursday afternoon into early Friday morning across parts of Oklahoma and northern Texas. ....Synopsis... An upper trough extending from the northern Rockies to southern CA will shift east on Thursday, extending from the northern Plains to the southern Rockies by Friday morning. Strong deep-layer southwesterly flow will overspread much of the southern/central Plains toward the Mid-MO Valley and Upper MS Valley by late afternoon into the overnight hours. A surface lee cyclone is forecast to deepen as the upper trough and stronger height falls spread east over the Rockies. The resulting increase in southerly low-level flow will quickly transport moisture northward across TX/OK into eastern portions of the central Plains during the afternoon and continuing through the overnight hours. A conditional risk of severe storms will exist near/just east of a surface dryline across parts of OK/north TX. Meanwhile, elevated thunderstorms ahead of the surface low across parts of NE are expected during the evening and may pose a marginal hail threat. ....Central/Eastern NE... Strong warm advection through the first half of the period will transport 50s surface dewpoints northward across eastern NE ahead of the surface low tracking northeast across the central Plains. Steepening midlevel lapse rates will contribute to modest elevated instability amid strong vertical shear and increasing large-scale ascent. This may be sufficient to support a marginal hail threat with convection developing near 00z. ....OK/TX Vicinity... The severe risk across the southern Plains will likely remain conditional from late Thursday afternoon into early Friday morning. The main upper trough will remain too far west for strong ascent and height falls to overlap increasing boundary-layer moisture and favorable vertical shear until near the end of the forecast period. Capping will likely preclude convection through peak heating. However, forecast soundings indicate varied strength of the cap, and the 00z GFS/ECMWF/GEFS show a weak QPF signal near the dryline by 21-00z. There are some indications that a weak lead shortwave impulse may eject from northern Mexico/southwest TX toward OK during the afternoon. It is uncertain if this will provide sufficient forcing along the dryline to establish convection. If a storm can develop, low to mid 60s F surface dewpoints and steep midlevel lapse rates will support 1000-1500 J/kg MLCAPE amid supercell wind profiles. If a storm can become sustained, all severe hazards would be possible. However, this scenario is highly conditional. Overnight, a southwesterly low-level jet will increase and stronger height falls/large-scale ascent will begin to impinge on the area. Elevated thunderstorms may develop, posing a hail threat, toward Friday morning. ...Leitman.. 03/28/2023 $$ = = = 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) .