Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jul 04 2023 19:53:28 ACUS01 KWNS 041953 SWODY1 SPC AC 041951 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0251 PM CDT Tue Jul 04 2023 Valid 042000Z - 051200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EAST-CENTRAL CO...NORTHERN KS...AND SOUTHERN NE... ....SUMMARY... Scattered severe thunderstorms are possible from the southern Rockies to the Upper Midwest through mainly this evening. The most probable corridor for significant severe wind and hail is across a portion of eastern Colorado, northern Kansas, and southern Nebraska. ....Discussion... The only notable change this outlook update is to reduce severe probabilities across parts of the Upper Midwest due primarily to observational trends (i.e., visible satellite, surface observations, model-derived instability fields) showing weaker instability and a lessening risk for severe thunderstorms. ...Smith.. 07/04/2023 ..PREV DISCUSSION... /ISSUED 1130 AM CDT Tue Jul 04 2023/ ....Southern Rockies and the central Great Plains... Scattered thunderstorms will develop over the higher terrain near the UT/WY/CO border area east to the Front Range of CO/WY later this afternoon amid 40s to mid 50s surface dew points this morning. Steep mid-level lapse rates and fast mid-level westerlies centered over WY will support potential for a couple long-tracked supercells capable of large hail and severe wind gusts. This should evolve into a scattering of supercells over the central High Plains by early evening within a post-frontal, upslope flow regime. These will likely consolidate into an MCS as they spread away from the stronger mid-level flow and towards the deeply mixed boundary layer south of the front. The corridor immediately along the frontal zone will have the relatively greatest threat for significant severe wind gusts and a tornado or two. This MCS may merge with downstream convection that will likely develop separately in NE along the cold front. Overall, the hail threat should be mainly focused along the initial corridor of severe development and within the post-frontal regime, while the wind threat becomes the dominant hazard downstream until convection gradually subsides overnight. ....Upper Midwest... Remnants of a morning MCS have persisted across a portion of the Mid-MO Valley into the Twin Cities area. Attendant overturning and remnant cloud coverage is delaying diurnal destabilization, which 12Z guidance appears to be poorly handling overall. There appears to be a confined pocket of clearing behind the MCS outflow near a minor surface wave along the cold front. It is quite unclear whether there will be adequate recovery time across southeast SD northeastward across MN in the wake of this morning's activity. Conditionally, it will be a favorable setup for potential late afternoon to early evening redevelopment. Along the fringe of the stronger mid flow centered on the northern Great Plains overlapping the immediate frontal zone, 25-35 kt effective bulk shear would support organized multicell clusters and transient supercell structures. Primary change this outlook is to revamp the underlying hail probabilities which were forecast to be of equal weight and spatial extent as the wind probabilities. The large hail threat should be mainly focused along the initial corridor of severe development, with the wind threat largely being the dominant hazard downstream given the convective mode and weakness in the hodograph above the mid-levels. ....Mid and South Atlantic Coastal Plains to the Red River Valley... Primary change this outlook is to remove much of the hail probabilities which were forecast to be of equal weight as the wind probabilities for what will undoubtedly be a predominant sporadic damaging wind threat. A broad swath of moderate buoyancy with pockets of large buoyancy (MLCAPE around 3000 J/kg) are expected across parts of the Atlantic coastal plain across the Southeast through the Deep South to the Red River Valley. Weak to modest deep-layer shear and ill-defined synoptic/mesoscale features to help focus a more probable severe threat area, suggests a broad cat 1/MRGL risk remains warranted. Relatively greater potential for loosely organized multicell clusters and/or deeper updrafts is apparent over the eastern Carolinas and the Ark-La-Miss vicinity. $$ = = = 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) .