Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jun 27 2023 12:53:31 ACUS01 KWNS 271253 SWODY1 SPC AC 271251 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0751 AM CDT Tue Jun 27 2023 Valid 271300Z - 281200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM SOUTHWEST KS AND THE OK PANHANDLE ACROSS NORTHERN OK/SOUTHERN KS... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT ACROSS WESTERN/NORTHERN NE INTO SOUTHERN SD... ....SUMMARY... Storms producing severe winds of 60-85 mph and very large hail of 2-3 inches in diameter are probable in a corridor from southwest Kansas and the Oklahoma Panhandle across northern Oklahoma and southern Kansas this afternoon into tonight. More isolated large hail and damaging winds will be possible across parts of Nebraska and southern South Dakota. ....KS/OK to the Ozarks through tonight... A midlevel high will shift slowly eastward across TX, as a shortwave trough ejects east-northeastward from the central Rockies to the central Plains through tonight. This pattern will support lee cyclogenesis across eastern CO and the north/northwestward return of the richer low-level moisture (68-72 F dewpoints) from southern OK and the TX South Plains toward KS through the afternoon. The ongoing storms in central OK (and southwest AR) may persist through the day while moving eastward/southeastward along the moisture/buoyancy gradient and the edge of the stronger cap. In the wake of this morning convection, large buoyancy is expected (MLCAPE near 4000 J/kg) in a corridor from central/northern OK into southwest KS, as a result of 9 C/km midlevel lapse rates atop the moist axis, and along the north edge of the hottest surface temperatures. This same corridor will lie beneath the southern fringe of the stronger mid-upper west-southwesterly flow (40-50+ kt). Thunderstorm development is expected by mid afternoon immediately downstream from the Raton Mesa area in southeast CO, and storms will subsequently spread into southwest KS and possibly the OK Panhandle this evening. The initial storms will likely be supercells capable of producing very large hail of 2-3 inches in diameter. Temperature-dewpoint spreads will be higher in CO, but 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 an MCS appears likely, due to storm interactions/mergers in the steep lapse rate environment with intense downdraft potential. Swaths of severe gusts of 60-85 mph will be possible into tonight across southern KS/northern OK, and the threat for at least isolated damaging winds could persist into northern AR overnight. ....Northwest KS/NE/southern SD through tonight... In the wake of elevated morning storms associated with warm advection near 700 mb, moisture advection and surface heating will contribute to destabilization through the afternoon from northwest KS across NE into southern SD. Lee cyclogenesis across northeast CO will help sharpen a dryline by afternoon close to the longitude of the CO/KS border, which should focus widely scattered thunderstorm development later this afternoon into NE and possibly northwest KS. Moderate-strong buoyancy and relatively long/straight hodographs will favor supercells capable of producing isolated very large hail (2 to 2.75 inches in diameter) and isolated damaging winds. Though a relative gap is possible somewhere near northwest KS, confidence in the details is low, and the entire zone conditionally favors supercells. Otherwise, storms will be possible from northeast WY into western SD, and some elevated convection may persist while spreading eastward toward northeast NE overnight. Isolated large hail and strong-damaging gusts will be possible. ....Mid-Atlantic into eastern NY this afternoon/evening... A midlevel 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 have all been reduced compared to yesterday, in the wake of prior widespread convection and as the primary jet moves offshore. Still, slightly cooler midlevel temperatures and surface heating with residual moisture in cloud breaks could support isolated storms with gusty winds. ...Thompson/Mosier.. 06/27/2023 $$ = = = 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) .