Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 27 2023 12:44:28 ACUS01 KWNS 271244 SWODY1 SPC AC 271242 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0742 AM CDT Sat May 27 2023 Valid 271300Z - 281200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR PARTS OF THE SOUTHERN AND NORTHERN HIGH PLAINS... ....SUMMARY... Isolated to scattered severe thunderstorms appear possible across much of the High Plains this afternoon and evening. Large hail and severe gusts are the primary hazards. ....Synopsis... A Rex block persists from the Great Lakes to the Southeast, and as part of the blocking pattern, a baroclinic cyclone will drift northward toward the SC coast. The surface warm sector will remain offshore until later tonight, at which time the cyclone will be slowly weakening. Given the weakening flow aloft with time and poor phasing of stronger low-level shear with greater surface-based buoyancy, the threat for surface-based supercells to move inland appears low. Farther west, weak lee troughing will persist across the length of the High Plains from eastern NM to eastern MT, as subtle/embedded shortwave troughs northeastward and northward across the High Plains. ....Northern High Plains this afternoon/evening... Similar to yesterday, scattered thunderstorms are expected to form this afternoon near the lee trough and spread northeastward before weakening by late evening. Moderate buoyancy (MLCAPE of 1000-2000 J/kg) and effective bulk shear of 25-35 kt will favor a mix of multicell clusters and some marginal supercells initially, with storms growing upscale into bands during the evening. Occasional large hail and severe outflow gusts of 60-70 mph will be the main threats. ....Southern High Plains through early tonight... A couple of thunderstorm clusters have persisted since last night - one is east of Lubbock and the other is along the NM/TX border west of Amarillo. These storms will slowly weaken while moving southeastward the remainder of the morning, with residual clouds and outflow slowing surface heating from northwest TX into the TX Panhandle. Farther west and southwest, boundary-layer dewpoints in the mid 50s to low 60s persist across eastern NM and southwest TX. Surface heating in cloud breaks will again result in moderate-strong buoyancy (MLCAPE 1500-2500 J/kg), though vertical shear will be a little weaker compared to the previous couple of days. Scattered thunderstorms are expected to form along the east slopes of the higher terrain, as well as the weak lee trough and any lingering outflow boundaries later this afternoon, and spread eastward into this evening. The moisture/buoyancy and modest vertical shear will support the potential for some large hail with initial supercells, and isolated severe outflow gusts with any upscale growth into clusters. ...Thompson/Broyles.. 05/27/2023 $$ = = = 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) .