Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 26 2023 07:30:16 ACUS03 KWNS 260730 SWODY3 SPC AC 260729 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Mon Jun 26 2023 Valid 281200Z - 291200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS...AND IN THE UPPER MIDWEST... ....SUMMARY... An isolated severe threat will likely develop on Wednesday across parts of the Upper Midwest, and in the central to northern High Plains. ....Upper Midwest... An anticyclone will be in place on Wednesday across the south-central U.S., with a subtle shortwave trough in the north-central states moving eastward over the top of the anticyclone. At the surface, a cold front will advance southeastward into the mid Missouri Valley and central Plains. A moist airmass will be in place southeast of the front across much of the mid to upper Mississippi Valley. Moderate to strong instability appears likely to develop over parts of this airmass by afternoon. In spite of this, model forecasts show warm air aloft and a strong capping inversion across much of the region. Ahead of the shortwave trough, thunderstorm development in the late afternoon and early evening should be mostly confined to Iowa and Minnesota, where the cap will be weaker and more large-scale ascent is forecast. The models vary on convective coverage, with some solutions showing little convection, and others developing isolated clusters. If a storm cluster can develop far enough south, then an isolated severe threat would be likely. NAM forecast soundings over northwest Iowa at 00Z/Thursday have 0-6 km shear near 40 knots with 700 mb lapse rates around 7.5 C/km. This would support a large-hail threat with any supercell that can develop, in spite of the warm air aloft. An isolated wind-damage threat will also be possible. Due to uncertainty concerning the cap and the resultant amount of cell coverage, a Slight Risk will not be introduced at this time. ....Central and Northern High Plains... An upper-level trough will move across the western U.S. on Wednesday, as southwest mid-level flow remains from the Four Corners region northeastward into the central High Plains. An axis of moderate instability may develop by afternoon from the central Plains northeastward into the northern High Plains. Convection that forms in the higher elevations of central and eastern Wyoming will move eastward toward the instability axis during the late afternoon. Forecast soundings in eastern Wyoming at 00Z/Thursday have MLCAPE around 1500 J/kg with 0-6 km shear near 40 knots and 700-500 mb lapse rates near 7 C/km. This could be enough for marginal severe threat during the late afternoon and early evening. ...Broyles.. 06/26/2023 $$ = = = 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) .