Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 03 2023 08:30:08 ACUS48 KWNS 030830 SWOD48 SPC AC 030828 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0328 AM CDT Thu Aug 03 2023 Valid 061200Z - 111200Z ....DISCUSSION... ....Days 4-5/Sun-Mon -- Mid-MS/OH Valley east to NY/PA/MD/VA... A rather potent mid/upper shortwave trough for this time of year will develop eastward from the Mid/Upper MS Valley to the Northeast/Mid-Atlantic vicinity Sunday and Monday. At the surface, a deepening low will move across IA and WI/MI on Sunday, before lifting east/northeast across Ontario and Quebec on Monday. A trailing cold front will sweep across the Midwest and likely be approaching the I-95 corridor by Tuesday morning. Enhanced midlevel southwesterly flow associated with upper trough atop a very moist/unstable boundary layer will set the stage for a multi-day severe weather episode ahead of the eastward-advancing cold front. All severe hazards appear possible on Sunday from portions of eastern IA through southern WI/MI into much of IL/IN, northern KY, and western OH, as a linear convective system moves east across the region. Tornado potential likely will be focused closer to the surface low track, and along a warm front extending from the low east/southeast across parts of southern WI/MI into northern IL/IN. The system will continue east on Monday, impacting portions of the upper OH Valley/Lower Great Lakes/central Appalachians vicinity. The surface low will be shifting further northeast into Canada. Nevertheless, large-scale ascent associated with the upper trough, and moderate vertical shear atop very moist and unstable boundary layer will continue to support severe convection ahead of the eastward advancing cold front. Damaging winds will likely be the greatest concern on Monday. ....Day 6/Tue -- Northeast and the Central Plains... An upper trough and surface cold front will continue to move across New England on Tuesday. Some severe potential could continue across the region ahead of the front. However, uncertainty in timing of these features, along with potential detrimental impacts for widespread showers/cloudiness ahead of the front, preclude 15 percent severe probabilities at this time. Further west, 40 kt northwesterly flow will overspread the central Plains. While large-scale ascent appears somewhat nebulous, a moist and unstable airmass will be in place. Any modest vorticity maxima floating across the Rockies amid southeasterly upslope flow could support at least isolated severe thunderstorm potential. However, confidence in this scenario is too low to include 15 percent probabilities at this time. ....Days 7-8/Wed-Thu -- MO Valley to OH Valley vicinity... Forecast guidance suggest another amplified upper trough will track east across central portions of the CONUS at the end of the period. This could bring another bout of severe storms to portions of the MO/MS/OH Valley vicinity. Enough spread exists in guidance to preclude severe probabilities at this time, but trends will be monitored and probabilities may become necessary is later outlooks. ...Leitman.. 08/03/2023 = = = 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) .