Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 06 2023 20:00:30 ACUS01 KWNS 062000 SWODY1 SPC AC 061959 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sat May 06 2023 Valid 062000Z - 071200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN TEXAS INTO EXTREME SOUTH-CENTRAL OKLAHOMA... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF IOWA...ILLINOIS...AND NORTHERN MISSOURI... ....SUMMARY... Intense severe thunderstorm development remains likely during the late afternoon and evening across a portion of the southern Great Plains. Very large hail and destructive wind events are possible across the Big Country and North-Central Texas into southern Oklahoma. Severe thunderstorms capable or producing a few tornadoes, very large hail, and damaging gusts remain a concern across parts of the Mid-Mississippi Valley States this evening into tonight. ....20Z Update... One of the primary changes made to the Day 1 Outlook was to remove the Category 1/Marginal Risk from LA. Multiple training MCSs have overturned the airmass in this region, reducing buoyancy and the associated severe threat. The only other change to the Day 1 Outlook was to adjust the severe probabilities over IA into northwestern MO to align with a baroclinic zone, where a focus for initial discrete supercells exists before storms potentially grow upscale into an MCS later this evening. Otherwise, the remainder of the Outlook remains on track, with severe hail and wind likely with outflow dominant storms across the southern Plains. An instance or two of large hail may still accompany a small convective cluster across central IL (see Mesoscale Discussion 0688 for more details). Likewise, a couple of severe wind gusts remain possible with storms overspreading a relatively dry boundary layer over parts of NE into SD. ...Squitieri.. 05/06/2023 ..PREV DISCUSSION... /ISSUED 1105 AM CDT Sat May 06 2023/ ....TX/OK... A broad/flat upper trough is present today over the western states, with a ridge axis across the MS Valley. A diffuse surface dryline is analyzed over west TX, and will mix eastward through the afternoon and provide the focus for intense thunderstorm development later today. Full sunshine will lead to dry-adiabatic lapse rates throughout most of the low/mid troposphere today near the dryline. High-based storms are expected to develop by mid-afternoon from near Wichita Falls southward to west of San Angelo, where high CAPE values and sufficient flow will support supercells storms capable of very large hail and damaging winds. These storms will persist through much of the evening and spread eastward. Richer low-level moisture profiles and strengthening low-level winds during the evening will maintain the wind/hail risk while also increasing the potential for a tornado or two, although early outflow dominance may complicate storm modes. ....IA/MO/IL... a small cluster of strong-severe storms is ongoing this morning over northeast MO. The air mass ahead of this activity is relatively cloudy and only marginally unstable, leading to considerable uncertainty regarding the longevity of the severe risk. A few 12z CAM solutions do show convective maintenance through much of the afternoon, so will maintain the SLGT risk into central IL for this scenario. Farther north and west, southeasterly low-level winds will continue to transport an increasingly moist airmass into parts of northern MO and southern IA. Partial afternoon heating is expected to lead to moderate CAPE and the development of isolated thunderstorms. The storms that form will track eastward through the late afternoon and evening across southern IA/northern MO and eventually into western IL. Confidence is low regarding the location and timing of development, so have opted to make few changes to the ongoing SLGT risk. However, there is relatively high conditional potential for supercell storm structures capable of large hail and isolated tornadoes for those storms that can develop. $$ = = = 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) .