Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Sep 09 2023 12:53:23 ACUS01 KWNS 091253 SWODY1 SPC AC 091251 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Sat Sep 09 2023 Valid 091300Z - 101200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF EASTERN WY TO CENTRAL NE AND NORTHWEST KS...AND THE MID-ATLANTIC STATES... ....SUMMARY... The most likely corridors for potentially scattered severe thunderstorms will be across parts of the central Great and northern High Plains centered on the late afternoon to evening, and across parts of the Mid-Atlantic States this afternoon. ....NE/KS to the northern High Plains... Deep-layer wind profiles will be conducive to discrete supercells from late afternoon into this evening, focused along a surface front from central NE to northwest KS and within a post-frontal weak upslope regime to the northwest across the northern High Plains. A ribbon of around 1 inch PW values depicted in GOES imagery and sampled by the 12Z LBF sounding should be maintained from western KS into central NE. This combined with surface temperatures warming through the 80s along with steep mid-level lapse rates will support a confined corridor of 1000-2000 J/kg MLCAPE. A few to several high-based supercells should develop with large hail as the primary hazard, along with isolated severe wind gusts, initially across central NE and then southwestward into northwest KS. A strengthening southerly low-level jet during the evening may yield a small cluster evolving south over western KS with a continued wind/hail threat. The northern High Plains portion should similarly see a few to several supercells developing off the higher terrain in WY/far southern MT/southwest SD. While buoyancy will be weaker here and the boundary layer not as deep, 35-45 kt effective shear will be conducive to a few long-track cells capable of producing sporadic hail swaths up to around golf ball size, centered on eastern WY. ....NC to NY... While overall severe coverage will be less than the past couple days after prior overturning and increasingly meridional and weaker wind profiles, at least isolated damaging winds will be possible across much of the region. One area of focus for slow-moving multicell clustering will be downstream of an MCV over southwest PA. Here, pockets of moderate insolation should support a plume of 1000-2000 J/kg MLCAPE centered on the DE Valley. As storms develop and impinge on this buoyancy plume this afternoon, coincident with a mesoscale belt of slightly stronger mid-level flow as sampled by recent CCX VWP data, the potential for sporadic damaging winds along with isolated, marginally severe hail should increase. Farther south, convection attendant to an MCV near the coastal SC/NC border will likely expand in coverage northward, especially from midday to mid-afternoon. Relatively greater insolation early in the day should support a broad plume of weak to moderate buoyancy and steepen low-level lapse rates adequately for localized damaging wind gusts. With somewhat weaker mid-level lapse rates and slightly less deep-layer shear relative to farther north, potential for a more organized severe threat appears nebulous at this time. ....South-central to southeast TX... Remnant outflow associated with convection that has recently spread into the northwest Gulf should serve as a focus for renewed late afternoon to early evening thunderstorm development. Hot temperatures in excess of 100 F will again be common to the west of this boundary in central and south TX. There is uncertainty in just how far northwest convection may form in central TX, with greater confidence closer to the coastal plain. While some initial large hail will be possible near the coast, the primary threat should be sporadic severe wind gusts. The overall threat coverage appears most likely to be isolated at this time, but a mesoscale corridor of greater severe wind gust potential may become evident later. ....Great Basin... Along the leading periphery of gradually increasing PW values from the southwest, at least isolated high-based thunderstorms should develop later this afternoon. Within a modest zonal mid-level flow regime, any of these high-based storms will be capable of producing dry microbursts reaching severe criteria. ...Grams/Mosier.. 09/09/2023 $$ = = = 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) .