Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Oct 14 2023 19:45:20 ACUS01 KWNS 141945 SWODY1 SPC AC 141943 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0243 PM CDT Sat Oct 14 2023 Valid 142000Z - 151200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THROUGH EARLY EVENING ACROSS COASTAL NORTH CAROLINA AND FAR SOUTHEAST VIRGINIA... ....SUMMARY... Isolated strong/damaging gusts and a brief tornado are possible through early evening over portions of coastal North Carolina and far southern Virginia. ....Coastal NC/southeast VA... Only minor adjustments have been made to the Marginal (level 1 of 5) risk area, mainly across NC, based on current location of the surface low and cold front. Some modest cumulus development has occurred along the front as weak destabilization occurs in a narrow corridor behind early showers/convection. A few strong storms producing locally strong gusts or a brief spin-up will remain possible through early evening. ...Leitman.. 10/14/2023 ..PREV DISCUSSION... /ISSUED 1117 AM CDT Sat Oct 14 2023/ Across the CONUS, moderate mid-level zonal flow, punctuated by several shortwave troughs, will slowly amplify through the forecast period. A broad upper low over the eastern Canadian Maritimes will retrograde westward while the primary positive tilt shortwave trough over the OH Valley deepens. A second vort max over the northern Plains will impinge on the western flank of the OH Valley shortwave further deepening the conglomerate into a broad upper low over the eastern US by the end of the forecast period. Behind the amplifying upper low, broad ridging will develop over the western US. At the surface, a broad area of low pressure over the OH Valley was trailing a cold front south toward the central Gulf Coast. A cool and stable post-frontal air mass within high pressure over much of the central and western CONUS will shunt thunderstorm probabilities eastward toward the Atlantic Coast. A second coastal low near the Carolinas will gradually move inland marking the effective edge of the remaining warm sector and isolated severe thunderstorm chances for today outside of the southern FL peninsula. ....Coastal North Carolina into far southern Virginia.... As the broad upper low over the eastern CONUS deepens, the primary shortwave over southern OH will shift southeastward overspreading much of the middle Atlantic Coast. Deep-layer ascent from the shortwave and moderate westerly flow will allow the coastal low to deepen slightly as it moves inland over portions of eastern NC and southern VA. Warm and moist surface flow (dewpoints in the upper 60s-70s F) should support a narrow, weakly unstable warm sector along the immediate coast through the afternoon. Ongoing cloud cover and modest to poor mid-level lapse rates will continue to limit buoyancy, but by early afternoon a few cloud brakes and inland warm advection will allow for weak destabilization of (500-1000 J/kg MUCAPE). This may support a few stronger updrafts as storms develop near the surface triple point while it moves into eastern portions of NC and eventually far southern VA. Despite limited buoyancy, deep-layer shear is favorable for storm organization into short linear segments and perhaps supercells. Strong lower tropospheric flow and water loading atop neutral lapse rates may support a few damaging wind gusts with the strongest storms. Clockwise curved, but relatively modest sized low-level hodographs may also allow for low-level updraft rotation and the potential for a brief tornado, especially with any sustained supercell structures over coastal parts of NC. While confidence in severe coverage is not overly high, isolated severe storms are possible for a few hours this afternoon as the low deepens before moving offshore this evening. ....OH Valley... As the broad surface low slowly merges with the secondary coastal low this afternoon, weak mid-level warm advection along and east of an occluding front may support low-topped thunderstorms from eastern OH into parts of the central Appalachians. With buoyancy generally below 250 J/kg owing to cooler and drier surface conditions, storms are not expected to be strong or organized. However, abundant vertical vorticity beneath the upper low and along the wind shift/frontal zone may support a few funnel clouds or small hail/graupel with the more sustained updrafts. Given the lack of greater severe potential owing to little buoyancy and shear, no Marginal Risk will be introduced. $$ = = = 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) .