Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Aug 13 2023 05:52:49 ACUS02 KWNS 130552 SWODY2 SPC AC 130551 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CDT Sun Aug 13 2023 Valid 141200Z - 151200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE/UPPER OHIO VALLEY AND MID-ATLANTIC STATES... ....SUMMARY... Severe thunderstorms are possible Monday afternoon and evening across the Middle/Upper Ohio Valley and Mid-Atlantic States. ....Synopsis... A shortwave trough will begin the period extended from the Upper Midwest southwestward into central KS, with strong mid-level flow of 50-70 kt anticipated through its base. This shortwave is forecast to progress eastward throughout the day, with its attendant mid-level flow strengthening as it spreads eastward across the OH Valley. Primary surface low associated with this shortwave will likely be over eastern IA early Monday morning, before then progressing eastward across northern portions of OH Valley throughout the day. An attendant cold front will extend southeastward from this low, moving eastward/southeastward across the OH, TN, and Mid MS Valleys as the low moves eastward. ....OH Valley into the Mid-Atlantic... Surface pattern preceding the shortwave trough mentioned in the synopsis will be complicated by the evolution of thunderstorms Sunday night, with the low-level moisture field influenced by this overnight activity as well. Current expectation is for the cluster of showers and thunderstorms remaining from the overnight activity to be over OH and WV early Monday morning. Outflow from these storms will likely extend across northern KY to another surface low over the southern IL vicinity. This triple-point low is then forecast to progress east-northeastward across the OH Valley just ahead of the approaching cold front. As it does, the outflow will return north as a warm front, with low 70s dewpoints expected within the warm sector. This evolution is expected to result in airmass destabilization ahead of the cold front. Large-scale ascent associated with the shortwave trough will spread over the OH Valley as well. Thunderstorm development is anticipated along and ahead of the front as a result, with moderate vertical shear supporting some organized storm structures. Damaging gusts appear to be the primary threat, with storms expected to mature into bowing line segments. A somewhat separate scenario is anticipated during the afternoon and evening downstream across VA and NC, as the vorticity maximum left from the Sunday night's storms moves into the region during peak heating. Mesoscale ascent attendant to this vorticity maximum coupled with low-level convergence on a weak surface trough will likely result in thunderstorm development once the airmass destabilizes. Vertical shear will be weaker here, but strong buoyancy should still result in robust updrafts and a few strong to severe storms. ....Southwest... Mid-level moisture is expected to move through the western periphery of the southern Plains ridging and into the region on Monday. Widespread thunderstorm coverage is expected Monday afternoon and evening as the airmass destabilizes amid this favorable mid-level moisture and strong heating. A few strong downbursts are possible from these high-based storms. However, generally southerly flow throughout the column may keep storms out of the lower elevations where gusts are more likely. As such, no probabilities were introduced with this outlook. ...Mosier.. 08/13/2023 $$ = = = 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) .