Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 27 2024 17:11:23 ACUS02 KWNS 271711 SWODY2 SPC AC 271709 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1209 PM CDT Tue Aug 27 2024 Valid 281200Z - 291200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE DAKOTAS...AND FROM OHIO TO THE NORTHERN MID-ATLANTIC COAST... ....SUMMARY... Severe thunderstorms are expected on Wednesday from parts of Ohio to the northern Mid-Atlantic coast, and across parts of North and South Dakota. ....Mid-MS/OH Valleys to the Mid-Atlantic... Uncertainty remains this forecast cycle, particularly from around central PA eastward to the northern Mid-Atlantic Coast/Chesapeake Bay vicinity. Severe thunderstorm probabilities have been focused along and just ahead of a southward sagging cold front and instability gradient from central OH to the NJ coast. Rich boundary-layer moisture (dewpoints in the upper 60s to mid 70s F) will contribute to a corridor of MLCAPE around 2000-4000 J/kg from the Mid-MS Valley eastward to the NJ coast. Warm midlevel temperatures may lead to lingering inhibition, particularly across eastern portions of the Slight and Marginal risk areas. Height falls associated with troughing over eastern Canada will remain well north of the region, and resulting in somewhat nebulous large-scale ascent amid very modest vertical shear (effective shear magnitudes generally less than 25 kt). Convection from the Day 1/Tue period may be ongoing Wednesday morning across parts of the Great Lakes vicinity and shift east along the instability gradient/southward-sagging surface front through the afternoon. Vertical shear may be locally enhanced with any MCV that may be present with this activity, and damaging winds are possible as the downstream boundary layer destabilizes. Additional isolated thunderstorm development is possible from central PA/northern VA eastward to the coast. This activity could produce locally damaging gusts and perhaps small hail if capping can be overcome and longer-lived updrafts develop. Weak shear further west toward the Mid-MS Valley vicinity will likely preclude a more organized severe risk. However, strong heating amid the very moist/unstable airmass will support isolated strong/locally damaging gusts during the afternoon. ....Northern Plains... A robust upper cyclone will spread east from the northern Rockies to the northern Plains on Wednesday. Enhanced mid/upper southwesterly flow ahead of this feature will overspread the Dakotas, in conjunction with stronger height falls, from late afternoon into the overnight hours. At the surface, low pressure will deepen over the northern High Plains during the day, resulting in an increasing baroclinic zone across the northern Plains. Southeasterly low-level flow will transport 60s F dewpoints northwest ahead of a westward-advancing cold front. Steepening midlevel lapse rates and favorable boundary-layer moisture will support a corridor of strong instability (MLCAPE 2000-3000 J/kg). Forecast soundings indication supercell wind profile, with greater than 40 kt effective shear magnitudes and elongated/straight hodographs. Large hail, some potential to 3 inch diameter, will be possible in addition to severe wind gusts beginning near 00z and lingering into the nighttime hours. ...Leitman.. 08/27/2024 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .