Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jun 27 2023 19:56:03 ACUS01 KWNS 271955 SWODY1 SPC AC 271954 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0254 PM CDT Tue Jun 27 2023 Valid 272000Z - 281200Z ....THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHERN KANSAS AND FAR NORTHWEST OKLAHOMA ALONG THE BORDER... ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF SOUTHERN KANSAS AND NORTHERN OKLAHOMA...AND OVER WESTERN NEBRASKA... ....SUMMARY... Supercells evolving into a narrow bowing complex appear likely across parts of southern Kansas and northern Oklahoma from late afternoon through tonight. Very large hail and perhaps a tornado will be the main threat initially, followed by potential for a swath of destructive wind gusts in excess of 80 mph. ....KS/OK area... Air mass recovery is being closely monitored in the wake of the earlier storms which have moved into central AR. Cool air currently resides over northeast OK and southeast KS, but winds have continued to veer and warming is underway. Areas of midlevel clouds do exist but substantial heating is occurring over much of the area. As such, the air mass should continue to destabilize, especially from western OK and the Panhandles into southwest KS within the 70s F dewpoint axis. Midday soundings from AMA show very steep lapse rates through a deep layer, approaching 9 C/km from the surface to 500 mb. Stronger mid and high-level flow exists just north of this area (40-60 kt at DDC), which will support supercells capable of very large hail with the activity now forming over northeast NM and southeast CO. These storms should merge over time, producing a substantial cold pool with a narrow corridor of destructive winds forecast near the KS/OK border. For more information see MCD 1307. ...Jewell.. 06/27/2023 ..PREV DISCUSSION... /ISSUED 1130 AM CDT Tue Jun 27 2023/ ....Raton Mesa to the Ozarks and Lower MS Valley... A stout mid-level anticyclone will remain anchored across central TX with a couple of ridge-riding MCSs possible around it. A plume of large to extreme buoyancy will become centered from southwest KS to the Ark-La-Miss at peak heating amid 70s surface dew points and very steep mid-level lapse rates of 8-9 C/km atop the moist axis. A small elevated cluster in eastern OK may track southeast along the pronounced buoyancy gradient, with a possibility for surface-based development downstream of it along the effective front towards the Ark-La-Miss. The weak large-scale forcing for ascent lowers confidence in the overall scenario, but there is potential for multicell clusters to spread southeast into the Lower MS Valley later this afternoon. Primary threat will be scattered damaging winds. Outflow from the morning complex in OK has reinforced the baroclinic zone across central to southern OK, but the leading edge of 70s surface dew points in southwest OK will advect north into northwest OK by late afternoon. Initial thunderstorm development is expected by mid afternoon in the Raton Mesa vicinity, and storms will subsequently spread into southwest KS and the northern Panhandles by early evening. The initial storms will likely consist of a few supercells capable of producing very large hail of 2-3 inches in diameter. An increase in low-level shear this evening and increasing moisture with eastward extent could result in a window of opportunity for a tornado or two with the more discrete supercells. Thereafter, upscale growth into a small but particularly intense MCS appears probable, due to storm interactions/mergers in the very steep lapse rate environment and strengthening low-level jet. Localized swaths of destructive severe wind gusts from 80-110 mph will be possible into tonight across southern KS/northern OK. The overall threat will likely remain spatially confined owing to the pronounced EML/capping to its south and residual influence of this morning's convection, especially with eastern extent towards the Ozarks overnight. ....Northwest KS to ND... In the wake of elevated morning storms associated with warm advection near 700 mb, low-level moisture advection and surface heating will contribute to stronger destabilization from northwest KS into southwest SD where MLCAPE of 1500-3000 J/kg should be common. Farther north, more modest boundary-layer moisture will result in MLCAPE of 1000-2000 J/kg. Lee cyclogenesis across eastern CO will help sharpen the dryline by late afternoon close to the longitude of the CO/KS border, which should focus widely scattered thunderstorm development in northwest KS and western KS. Additional storms should develop over the Black Hills, with more isolated activity also possible into ND. With a mid-level jetlet crossing the southern Rockies into the central High Plains, relatively long/straight hodographs will favor a few intense supercells capable of producing very large to giant hail and isolated severe wind gusts centered on western NE. Some clustering may occur during the evening as a southerly low-level jet intensifies but pronounced MLCIN and lack of instability with eastern extent suggest the severe threat should wane into central to eastern portions of NE/KS/SD. ....Mid-Atlantic into eastern NY... A mid-level trough with embedded perturbations and an associated surface cold front will move slowly eastward across NY/PA and toward the Mid-Atlantic coast. Lapse rates, buoyancy and vertical shear have all been reduced compared to yesterday, in the wake of prior widespread convection and as the primary jet moves offshore. Still, slightly cool mid-level temperatures and surface heating with residual moisture in cloud breaks could support isolated damaging winds in the strongest storms today. $$ = = = 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) .