Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 25 2023 01:01:31 ACUS01 KWNS 250101 SWODY1 SPC AC 250059 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 PM CDT Thu Aug 24 2023 Valid 250100Z - 251200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN GREAT LAKES... ....SUMMARY... Severe thunderstorms associated with a swath of wind damage will be likely this evening across parts of southern Lower Michigan, northeast Ohio and far northwest Pennsylvania. Localized significant severe wind gusts in excess of 75 mph, along with a few tornadoes will be possible. A potential for wind damage and isolated large hail is also expected this evening in parts of the northern Plains. ....Great Lakes/Upper Ohio Valley/Southern and Central Appalachians... Water vapor imagery currently shows a mid-level anticyclone over the south-central U.S. On the northeastern periphery of this system, mid-level flow is west-northwesterly across the Great Lakes. A shortwave trough is evident over western and northern Lower Michigan. Large-scale ascent associated with this shortwave will provide support for continued thunderstorm development this evening. Ahead of this shortwave, thunderstorms are currently ongoing in central Lower Michigan. This convection is forecast to gradually grow upscale into a progressive line segment this evening into tonight, as the low-level jet strengthens. The linear MCS is expected to move east-southeastward across southeast Lower Michigan, Lake Erie, northeast Ohio and far northwest Pennsylvania. RAP analysis currently shows a strongly unstable airmass located ahead of the developing MCS. In addition, the WSR-88D VWP at Detroit has 0-6 km shear near 45 knots, with veered westerly flow in the low to mid-levels, and some speed shear in the mid-levels. This, combined with the strong instability and surface dewpoints in the upper 70s to mid 80s F will be favorable for damaging wind gusts along the leading edge of the MCS. Wind gusts greater than 65 knots will be possible near the more intense parts of the MCS. RAP forecast soundings by mid evening also have 0-3 km storm relative helicity increasing to between 200 and 250 m2/s2 suggesting a tornado threat will also be possible. The threat for tornadoes will exist with discrete supercells, and with bowing line segments near the leading edge of the MCS. Supercells will also likely be capable of isolated large hail. ....Northern and Central Plains... An upper-level ridge is currently evident on water vapor imagery across the central and northern Plains. A subtle shortwave trough is currently moving eastward through the northern Plains. Ahead of this feature, scattered thunderstorms are ongoing along a corridor of moderate instability. Along this corridor, the RAP is showing MLCAPE in the 1000 to 2000 J/kg range. These storms will move eastward toward a moist axis this evening, where surface dewpoints are generally in the mid to upper 60s F. In addition, RAP forecast soundings to the east of this convection show moderate deep-layer shear, with 30 knots of southwest flow at 800 mb and 50 knots of westerly flow at 500 mb. This may be favorable for a severe threat this evening with the stronger multicell line segments and rotating storms. Hail and isolated wind damage will be the primary threats. A marginal severe threat will also be possible across parts of northern Nebraska and western South Dakota this evening. ...Broyles.. 08/25/2023 $$ = = = 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) .