Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Mar 29 2023 05:26:40 ACUS02 KWNS 290526 SWODY2 SPC AC 290525 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Wed Mar 29 2023 Valid 301200Z - 311200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST NEBRASKA INTO SOUTHEAST SOUTH DAKOTA...AS WELL AS WESTERN NORTH TEXAS INTO EASTERN KANSAS... ....SUMMARY... Isolated strong storms may produce hail across parts of northern Nebraska into southeast South Dakota Thursday evening. A more conditional threat for severe thunderstorms will exist late Thursday afternoon into early Friday morning across parts of western north Texas, Oklahoma and eastern Kansas. ....Synopsis... A large-scale upper trough oriented from the northern Rockies to southern CA Thursday morning will pivot eastward through the period. The trough should be located from the northern Plains to the southern High Plains by 12z Friday. Stronger height falls will mostly occur over the southern/central Plains vicinity after 00z and intense deep-layer southwesterly flow will overspread the region. At the surface, lee cyclone development is expected across the central High Plains during the late afternoon/evening. The low will continue to deepen as it tracks east/northeast toward northeast NE/southeast SD/northwest IA by Friday morning. Increasing southerly low-level flow will quickly transport moisture northward across TX/OK ahead of a dryline extending southward from the low across central KS/western OK/west-central TX. Near-60s F dewpoints should be as far north as the OK/KS border by 00z, with a corridor of mid/upper 50s extending northward across eastern KS/NE to the surface low center by the end of the period. ....NE/SD... Elevated thunderstorms are expected to develop ahead of the approaching surface low in a strong warm advection regime during the evening. Cool boundary-layer temperatures beneath an EML will preclude surface-based instability. However, steep midlevel lapse rates will contribute to 500-1000 J/kg MUCAPE amid strong vertical shear (effective shear greater than 40 kt). This environment may support isolated hail with stronger cells Thursday evening. ....TX/OK/KS... Conditional severe probabilities will be maintained for Thursday. Stronger ascent is not forecast to impinge on the southern Plains vicinity until overnight. However, some guidance suggests a weak lead shortwave impulse will migrate across western TX/OK during the afternoon. It is uncertain if this will provide enough forcing in conjunction with strong low-level warm advection to overcome the EML between 850-700 mb. Some CAMs guidance show attempts at deep convection in the 21-00z period, with the most aggressive FV3 developing supercells along the dryline in western north TX and western OK. If storms can develop and become established, supercell wind profiles, steep midlevel lapse rates and moderate instability will support all hazards (tornado, hail and wind). Toward the end of the period, stronger ascent and more pronounced height falls will overspread the region. Forecast guidance suggests isolated thunderstorms may develop ahead of the eastward advancing dryline/Pacific cold front from eastern KS into OK. If this occurs, initial convection may be elevated. Regardless, steep midlevel lapse rates and strong vertical shear will support a hail threat. ...Leitman.. 03/29/2023 $$ = = = 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) .