Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 22 2023 16:36:03 ACUS01 KWNS 221635 SWODY1 SPC AC 221634 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Fri Sep 22 2023 Valid 221630Z - 231200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID-ATLANTIC STATES AND NORTH-CENTRAL HIGH PLAINS... ....SUMMARY... Severe thunderstorms are possible across parts of the north-central High Plains this afternoon and this evening. A few tornadoes are also possible over the coastal southern Mid-Atlantic/Tidewater region overnight into tomorrow morning. ....North-central High Plains... Scattered thunderstorms are still ongoing at midday across western portions of Nebraska/South Dakota, generally in association with a lead shortwave trough downstream of a more prominent upper trough over the northern Intermountain region. In this wake of this activity, the primary corridor of diurnal destabilization will be focused in a northwest/southeast-oriented corridor across eastern Wyoming into the Nebraska Panhandle and extreme southwest South Dakota. Aided by low-level upslope flow/differential heating and the approach of the upstream trough/speed max, the aforementioned corridor is where at least isolated severe storms are expected to develop into mid/late afternoon, and subsequently move through this relatively narrow corridor of modest instability (MLCAPE 750-1250 J/kg). Long hodographs with 40+ kt effective shear will support supercells capable of large hail (locally significant 2+ inch), and possibly some tornado risk given the relatively moist environment. These storms should spread east-northeastward across much of the north-central Plains tonight, with the potential for large hail and locally damaging winds continuing possibly into the overnight. ....Coastal southern Mid-Atlantic/Tidewater... The potential for supercells and a few tornadoes is expected to increase late tonight as Potential Tropical Cyclone 16 approaches the coast. Reference the National Hurricane Center for the latest track/intensity forecast details. While inland areas are currently stable with respect to surface-based convection, higher theta-e air will accompany a warm front shifting toward the coast late tonight, all while low/mid-level winds strengthen on the northern periphery of the Potential Tropical Cyclone. Supercell-favorable ingredients are expected to be maximized across coastal eastern North Carolina into far southeast Virginia. This is where MLCAPE in the 500-1500 J/kg range is possible, despite midlevel lapse rates only slightly greater than moist adiabatic. Enlarging and well-curved hodographs are expected, with effective SRH of 300-500 m2/s2. A few tornadoes are possible mainly during the overnight into early Saturday. ....Iowa... An MCV continues to drift east-northeastward across western Iowa at midday. While plentiful cloud cover and some showers/thunderstorms precede the MCV, modest destabilization should gradually occur mainly across eastern Iowa this afternoon. Some stronger to locally severe storms could develop accordingly, aided by influences of the MCV. ....Eastern Oklahoma/ArkLaTex... While a few stronger storms could occur today, severe potential is expected to remain very limited across the region as warm advection abates and mid-level lapse rates remain modest. ...Guyer/Squitieri.. 09/22/2023 $$ = = = 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) .