Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 02 2023 19:56:09 ACUS01 KWNS 021956 SWODY1 SPC AC 021954 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0254 PM CDT Sun Jul 02 2023 Valid 022000Z - 031200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND EVENING ACROSS THE MISSOURI BOOTHEEL...ADJACENT PORTIONS OF NORTHEASTERN ARKANSAS AND SOUTHERN ILLINOIS...NORTHERN WESTERN AND MIDDLE TENNESSEE...MUCH OF KENTUCKY AND ADJACENT SOUTHERN INDIANA AND SOUTHWESTERN OHIO... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND EVENING ACROSS PARTS OF NORTHEASTERN NEW MEXICO...THE TEXAS AND OKLAHOMA PANHANDLES AND ADJACENT SOUTHEASTERN COLORADO AND SOUTHWESTERN KANSAS... ....SUMMARY... Potential for an organizing cluster of storms capable of producing damaging wind gusts appears highest across the lower Ohio Valley through mid to late evening. ....20Z Update... Adjustments have been made to the categorical and probabilistic lines to account for the progression of the synoptic and sub-synoptic features and their associated influence on destabilization. Convection continues to increase along a weak frontal zone to the south and southeast of a still well-defined mid-level low migrating across east central Illinois into west central Indiana. Although models continue to indicate that the low will become increasingly sheared and weaken later this evening, a seasonably moist boundary layer across the lower Ohio Valley has become characterized by large CAPE on the order of 2000-3000 J/kg. Modestly steep low-level lapse rates, coupled with shear/momentum associated with a belt of 40 kt 500 mb flow centered roughly across Kentucky, seems likely to support the evolution of an organizing convective system with increasing risk of producing damaging wind gusts into this evening. As activity continues eastward later this evening and overnight, a less unstable and/or stabilizing boundary layer across the Allegheny and Cumberland Plateaus, into and across the Appalachians, is expected to weaken convection and result in diminishing severe weather potential. ...Kerr.. 07/02/2023 ..PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Jul 02 2023/ ....Deep South to the OH Valley... A shortwave trough over IL will lose amplitude as it moves east across IN/OH through tonight. To the south of this trough, a belt of 35-45 kt mid-level west-southwesterlies will persist from the Mid-South to the central Appalachians. Numerous clusters are expected to develop by late afternoon within a broad southwesterly low-level flow regime amid moderate to large buoyancy characterized by an expansive plume of MLCAPE from 2000-3500 J/kg. Activity along the fringe of the stronger mid-level flow over the Deep South to TN Valley and with north extent in IN/OH will generally consist of multicell clusters. More organized clustering with a few supercells should emanate from the MS/OH River confluence and expand/spread across KY/TN and along the OH Valley later this afternoon. These may evolve into faster-moving line segments and embedded bowing structures with the main threat being damaging winds. ....Lower Mid-Atlantic States... A pair of MCVs, one in the vicinity of southwest VA and the other over western PA may help focus downstream scattered thunderstorm development this afternoon. With weak mid-level lapse rates persisting north of the lee of the southern Appalachians per 12Z observed soundings, robust boundary-layer heating will be necessary to destabilize across the region. This appears to be underway from NJ south across most of VA into NC. With relatively stronger mid-level westerlies compared to previous days, there will be sufficient deep-layer shear for organized multicell clustering and perhaps transient supercell structures. Overall setup should support a primary threat of isolated to scattered damaging winds into early evening. ....Southern High Plains... Downstream of a subtle mid/upper trough moving southeast over the southern Rockies, scattered thunderstorms will tend to be focused over the Raton Mesa/Sangre de Cristos later this afternoon. Within this northwest flow regime, deep-layer shear will be weak outside of the Raton Mesa to western Panhandles vicinity. A well-mixed boundary layer will support a primary threat of dry microbursts from slow-moving high-based storms. Somewhat greater potential for a briefly organized cluster remains apparent across northeast NM into the western Panhandles during the late afternoon to early evening. ....Northeast ND and northwest MN... The downstream influence of a pronounced shortwave trough shifting east across the Canadian Prairies will aid in a surface cyclone tracking from southeast SK across southern MB through this evening. Attendant surface cold front will likely increasingly overtake a leading surface trough this evening in northeast ND. While the greater severe threat will probably remain north of the international border, trailing convective development may brush far northeast ND/northwest MN with a threat for isolated large hail and damaging winds for a few hours centered around 03Z. $$ = = = 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) .