Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 11 2023 16:30:57 ACUS01 KWNS 111630 SWODY1 SPC AC 111629 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Sun Jun 11 2023 Valid 111630Z - 121200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT FOR THE MID-SOUTH AND TN VALLEY REGIONS... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON INTO EARLY TONIGHT FOR SOUTHEAST CO AND VICINITY...AND ACROSS NORTH TX... ....SUMMARY... Severe thunderstorms capable of damaging winds and hail are expected across a broad portion of the Tennessee Valley and Mid-South this afternoon and evening. Severe thunderstorms are also possible across the south-central High Plains and North Texas. ....Mid-South/TN Valley region through tonight... Around the southern periphery of a closed midlevel low over the upper Great Lakes, embedded shortwave troughs will move eastward over the lower OH and TN Valleys through early tonight. An associated surface cyclone will likewise develop eastward along and just north of the OH River, as a trailing pre-frontal trough and cold front move southeastward across the Mid-South and southern Plains through tonight. Clouds are fairly widespread as of late morning from the southern Appalachians northward into the OH Valley and westward into the mid MS Valley. A little south of the thicker clouds and surface cyclone track, there is a corridor of stronger surface heating from south central KY into the Mid-South, where temperatures will warm into the 80s with mid-upper 60s dewpoints. These surface conditions beneath midlevel lapse rates of 7-7.5 C/km will drive MLCAPE of 1500-2500 J/kg with minimal convective inhibition. Scattered thunderstorm development is expected by early-mid afternoon in the zone of weak low-level confluence/convergence associated with an embedded midlevel speed max, along the edge of the thicker clouds from central KY into western TN and AR. The moderate-strong buoyancy and midlevel flow near 40 kt will support a mix of multicell clusters/line segments capable of producing damaging winds and large hail. There will be somewhat stronger deep-layer flow/shear and a little greater potential for supercells across the Mid-South later this afternoon/evening. The convection will continue to spread eastward and southeastward across the TN Valley early tonight, with some continued damaging-wind threat. Other scattered thunderstorms could form this afternoon/evening to the west of the thicker clouds across the southern Appalachians. The stronger wind profiles/vertical shear will be west and north of this area through the afternoon, so the primary severe threats will be damaging downburst winds and marginally severe hail this afternoon/evening. Uncertainty increases with eastward extent due to the widespread clouds/rain from northeast GA into western NC and vicinity, and the primary increase in flow/shear will tend to occur after the muted diurnal cycle. ....Southern High Plains through tonight... Post-frontal, upslope flow is established this morning from eastern CO into northeast NM. Though not particularly large, buoyancy will be sufficient for supercells forming and moving eastward off the Raton Mesa, given easterly low-level inflow and relatively long hodographs. Large hail in excess of 2 inches in diameter and severe outflow gusts of 60-70 mph will be the primary severe threats, though an isolated tornado could also occur. Convection will likely persist into the overnight hours, immediately downstream from an embedded mid-upper speed max that will move east-northeastward from AZ to NM. Storm development is much less certain farther south into northeast NM and the TX Panhandle/South Plains. If a storm were to form along the stalled front this afternoon, it would potentially become supercellular with a conditional large hail threat. ....North TX late this afternoon into early tonight... Strong surface heating is underway to the south of a pre-frontal trough and weak cold front that are moving slowly southward across OK. As surface temperatures warm well into the 90s, convective inhibition will diminish and MLCAPE will increase to 3000-4000 J/kg. Low-level flow will remain rather weak, but deep-layer flow will be strong enough to support the potential for a few splitting supercells (given relatively straight hodographs with effective bulk shear of 35-40 kt). Isolated very large hail up to 2.5 inches in diameter and damaging gusts will be the main threat with these storms from late afternoon into early tonight. ....Great Basin this afternoon/evening... Embedded speed maxima will rotate northward around the eastern periphery of the midlevel low over southern CA. The ascent attendant to the speed maxima, in concert with daytime heating, will support clusters of high-based storms capable of producing a few strong-severe outflow gusts. ...Thompson/Thornton.. 06/11/2023 $$ = = = 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) .