Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 06 2023 05:47:28 ACUS01 KWNS 060547 SWODY1 SPC AC 060545 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CDT Sat May 06 2023 Valid 061200Z - 071200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN PLAINS... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SOUTHERN PLAINS ENH AND ACROSS PARTS OF THE MID-MISSISSIPPI VALLEY... ....SUMMARY... Severe thunderstorms are expected late afternoon/evening across portions of the southern Plains. Very large hail and severe wind gusts are the primary risks. Isolated severe thunderstorm potential will also exist across parts of the Mid-Mississippi Valley. Large hail is the main threat. ....Southern Plains... Main upper ridge has shifted east of the southern High Plains. This has allowed a few weak disturbances to eject northeast into this region the last few days, enhancing convection along/east of the dryline. While it's not entirely clear, latest water-vapor imagery suggests a weak disturbance may once again approach west TX around peak heating. This evolution suggests the dryline will retreat a bit farther west and models are more aggressive increasing 850mb flow across TX into OK by early evening. Early this morning, remnants of diurnally driven convection are progressing across central into east TX. This activity has disrupted boundary-layer moisture across north-central TX, but lower-mid 70s surface dew points are holding along the southwestern flank of the slow-moving MCS. Current thinking is moisture should easily advance north behind this convection during the day and very strong instability will evolve as temperatures warm rapidly into the lower 90s. NAM forecast sounding for ABI at 22z exhibits 5000 J/kg SBCAPE with very steep lapse rates, though surface-6km shear is not forecast to be that strong (20kt). Soundings exhibit very strong instability into southern OK by early evening. Convection should develop near/east of the dryline by 22z across west/northwest TX then spread/develop into southern OK. Initial activity may be supercellular in nature despite the marginal wind profiles; however, upscale growth may ultimately lead to an MCS that would track near the Red River after sunset. Very large hail can be expected with late afternoon/evening supercells. Otherwise, severe winds may accompany the MCS if it organizes adequately. ....Mid-Mississippi Valley... MCS has evolved and is propagating east across central NE early this morning, aided in part by a weak short-wave trough and LLJ. LLJ is forecast to veer to the southwest across eastern KS/MO by 18z which will focus a corridor of warm advection from IA into eastern MO/IL. Convection, in some form, will likely persist along the nose of the LLJ, possibly expanding in areal coverage within the warm advection zone. Forecast soundings suggest most of this activity should be elevated and the primary risk will be hail. There is considerable uncertainty how this activity will ultimately evolve. However, due to the westerly component, moisture/instability may spread farther east across IL into western IN late. This may be enough for a few strong/isolated severe thunderstorms late in the period. ....Southeast LA Region... Weak mid-level short-wave trough is associated with an MCS that is propagating into east TX early this morning. This feature will advance downstream and aid renewed convection across southeast LA where adequate moisture/instability currently reside. Deep-layer flow is not forecast to be that significant but hail/wind could be noted with stronger daytime storms. ...Darrow/Lyons.. 05/06/2023 $$ = = = 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) .