Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jun 24 2023 06:01:32 ACUS01 KWNS 240601 SWODY1 SPC AC 240600 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sat Jun 24 2023 Valid 241200Z - 251200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM IOWA INTO CENTRAL/NORTHERN MISSOURI...SOUTHERN MINNESOTA...AND WESTERN ILLINOIS... ....SUMMARY... Severe thunderstorms, associated with wind damage, large hail and perhaps a couple of tornadoes, will be possible from parts of Iowa and Minnesota into the mid Mississippi Valley this afternoon and evening. ....Synopsis... A seasonably strong mid/upper-level cyclone is forecast to move eastward from the northern Great Plains toward the upper Midwest today. An attendant surface low is expected to move slowly eastward across the eastern Dakotas, as a cold front moves through parts of the northern/central Plains. ....Iowa into MN/northern MO/western IL... An MCS may be ongoing at the start of the period somewhere from extreme southeast SD/eastern NE into western/central IA and southern MN. This could pose a threat of localized severe gusts early in the day, though a general weakening trend is expected through most of the morning (except possibly farther south along the outflow). In the wake of morning convection, some recovery of low-level moisture and instability is expected, though the details remain unclear due to uncertainty regarding the outflow boundary position and potential for regenerative development through the day within a low-level warm advection regime. However, with a westerly midlevel jet expected to increase to the south of the mid/upper-level cyclone during the afternoon and evening, wind profiles will become increasingly favorable for organized convection across much of IA into northern MO and perhaps southern MN. A few supercells will be possible near/north of any remnant outflow boundary, and potentially along the cold front as it approaches the region from the west during the late afternoon and evening. Hail (possibly very large) will be possible with any supercell development. Some tornado threat may also evolve, depending on details regarding outflow modification in the wake of morning convection. Another area of brief tornado potential may develop into central/northern MN, where relatively low-topped convection may develop closer to the surface cyclone. Backed surface winds and sufficient low-level shear/SRH may support transient rotation with the stronger storms. ....Lower/mid MS Valley and vicinity... Convection may intensify or redevelop later today into parts of central/eastern MO, where the southern extent of outflow from the overnight MCS impinges upon strong buoyancy. While midlevel flow will be somewhat weaker compared to areas farther north, deep-layer shear will be sufficient to support a couple of supercells within this regime, with a threat of large hail and localized damaging gusts. Some upscale growth into a southeastward-moving MCS could occur, which would potentially spread a damaging-wind threat into a larger portion of the lower MS Valley. However, this scenario remains highly uncertain, and will depend on mesoscale details regarding the evolution of the early-morning MCS and its attendant outflow. Aside from the scenarios described above, widely scattered strong thunderstorm development will be possible across parts of LA into southern MS within a weakly forced but also weakly capped and strongly unstable environment. Midlevel flow will be relatively weak, but veering winds with height may support a few strong multicells and/or a marginal supercell capable of producing large hail and locally damaging gusts. ....Southwest into north-central TX... Widely scattered high-based convection will be possible this afternoon and evening from southwest into northwest/north-central TX, within a hot and well-mixed environment. Any deep convection within this environment would pose a threat for isolated downbursts. Deep-layer flow/shear may also be marginally sufficient to support a hail threat, especially from near the Big Country region into north-central TX. ...Dean/Lyons.. 06/24/2023 $$ = = = 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) .