Subj : DAY1SVR: Day 1 Convective Outlook Resent 1 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 13 2025 16:47:27 ACUS01 KWNS 131646 SWODY1 SPC AC 131646 Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 1146 AM CDT Wed Aug 13 2025 Valid 131630Z - 141200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH DAKOTA AND NORTH-CENTRAL NEBRASKA... ....SUMMARY... Scattered severe wind gusts and isolated large hail may occur across parts of the northern/central Plains this evening and overnight. Thunderstorms across portions of the Northeast and Mid-Atlantic may produce occasional damaging winds this afternoon. ....Northern/Central Plains... Recent satellite imagery shows a low-amplitude shortwave trough moving through southwest MT. This shortwave is forecast to continue eastward along the MT/WY border vicinity today, before continuing through the Dakotas/NE tonight. The airmass preceding this shortwave across southeast MT/northeast WY is relatively dry, with dewpoints currently in the low to mid 50s. Greater low-level moisture is in place farther east, with dewpoints increasing into the low 60s across south-central SD and north-central NE. Southerly low-level flow is anticipated throughout the day, helping to offset some of the mixing expected amid strong diurnal heating. This should result in a modestly moist, deeply mixed airmass across the southeast MT/northeast WY/western SD vicinity by the late afternoon when the forcing for ascent attendant to the approaching shortwave reaches the region. This modest large-scale ascent show work in tandem with robust daytime heating and localized orographic effects near the Black Hills to initiate thunderstorms. High-based storms are anticipated initially, which could result in strong outflow with any more mature storms. A few instances of hail as possible as well. Greater low-level moisture and buoyancy will be in place farther east (i.e. into more of western/central SD), which will combine with persistent large-scale forcing for ascent and a strengthening low-level jet to support upscale growth into a convective line. This should foster a continued threat for damaging gusts into south-central SD and far north-central NE this evening. The threat should diminish with eastern extent given nocturnal stabilization and increasing convective inhibition. ....Northeast/Mid-Atlantic... Dewpoints currently range from the low 70s over the northern Mid-Atlantic into the low 60s across northern NH/VT. Thunderstorms are already developing within this moist and moderately buoyant airmass as large-scale ascent attendant to upper troughing advancing eastward over Ontario/Quebec glances the region. Deep-layer vertical shear is expected to remain weak throughout the day (i.e. effective bulk shear generally less than 25 kt), which should limit overall storm strength and organization. Even so, steep low-level lapse rates could aid in the development of occasionally damaging gusts with any of the deeper convective cores. Greater buoyancy could result in a relatively higher probability for damaging gusts from the NY Hudson Valley into eastern PA/NJ. Refer to recently issued MCD #1938 for additional information. ...Mosier/Squitieri.. 08/13/2025 = = = 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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .