Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Aug 07 2023 12:46:21 ACUS01 KWNS 071246 SWODY1 SPC AC 071244 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0744 AM CDT Mon Aug 07 2023 Valid 071300Z - 081200Z ....THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FAR EASTERN KY/NORTHEAST TN/NORTHWEST NC...WESTERN AND NORTHERN VA...SOUTHERN AND EASTERN WV...CENTRAL MD...AND FAR SOUTH-CENTRAL PA... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SEPARATELY OVER THE CENTRAL HIGH PLAINS... ....SUMMARY... A severe weather outbreak is possible across parts of the eastern U.S. today with widespread damaging winds, locally destructive, and isolated tornadoes as the greatest threats from the southern and central Appalachians to the Mid-Atlantic States. ....Southeast to the Upper OH Valley to the Mid-Atlantic States... A shortwave trough over the Lower OH Valley will advance across the northern Appalachians by this evening. A pair of 500-mb speed maxima from 55-65 kts are expected to be centered by late afternoon across eastern KY/TN and southern WV into western VA/NC, and separately over the Mid-South. Peak flow within an expansive 700-mb jet should be centered between the 500-mb maxima across the TN Valley. A plume of large potential buoyancy supported by high PW and steep mid-level lapse rates, and centered over the Mid-South/TN Valley will expand east-northeast towards the central/southern Appalachians with an expansive swath of MLCAPE from 2000-3500 J/kg expected by peak heating. The 12Z BNA sounding well-sampled this potentially volatile environment. To the north of the steeper mid-level lapse rate plume, minimal inhibition will result in scattered thunderstorms forming by midday centered on far southern OH across eastern KY ahead of the aforementioned trough. This activity will progress into an increasingly favorable thermodynamic and kinematic environment downstream, yielding many supercells capable of producing large hail, damaging winds, and tornadoes. Upscale growth into several linear clusters with embedded supercells is anticipated during the afternoon as convective coverage becomes widespread from PA/MD south-southwest across the southern Appalachian states. Forecast soundings suggest the greatest tornado threat will probably exist across eastern KY/TN northeast across southern/eastern WV, western VA, central MD and into southeast PA. Given the supercell wind profiles, significant severe wind gusts will also be possible on a localized basis. Across the Southeast, the separate mid-level speed max approaching the Mid-South, aiding in the low-level warm-advection regime of elevated thunderstorms over OK/AR this morning, will likely support scattered surface-based thunderstorms forming across the TN Valley by early afternoon. With large buoyancy downstream within the gradient of the strong low to mid-level flow, an extensive linear MCS will likely develop and spread east-southeast across the Carolinas and GA. Widespread damaging winds will be possible here as well, with convection likely weakening towards/after sunset as it approaches the south Atlantic coast. ....Central High Plains... A 50-60 kt mid-level speed max should become centered near the NE/CO/KS border area by late afternoon with approach of a low-amplitude shortwave impulse currently over southeast ID. This will overlap a confined north/south-oriented corridor of moderate buoyancy with MLCAPE of 1500-2500 J/kg along a lee trough across the similar tri-state area. Initial high-based thunderstorm development is anticipated off the higher terrain of CO/WY and will intensify as it impinges on the larger buoyancy during the early evening. A few supercells with very large hail will be possible along with a meso-beta scale corridor favorable for a tornadic supercell or two. Clustering of supercells may yield a short-duration uptick in severe wind gust potential across parts of western KS before convection spreads away from the relatively narrow instability plume and encounters increasing MLCIN after sunset. ...Grams/Broyles.. 08/07/2023 $$ = = = 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) .