Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 28 2024 08:58:04 ACUS48 KWNS 280857 SWOD48 SPC AC 280856 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Aug 28 2024 Valid 311200Z - 051200Z ....DISCUSSION... Medium-range global models continue to suggest limited severe potential Days 4-5 (Saturday and Sunday) largely within the northeastern quarter of the country, followed by several days of what appears likely to be minimal severe risk through the remainder of the period. Day 4/Saturday, upper-level height falls are progged to shift across the Great Lakes/Midwest/Northeast, as a strengthening upper trough advances east-southeastward across Ontario and the Upper Great Lakes region. A weak cold front will cross the Lower Great Lakes/Appalachians, with likelihood for showers and thunderstorms accompanying this front. However, with stronger flow aloft limited to areas from Pennsylvania northward, where instability should remain limited, overall severe risk appears at this time to remain too low to warrant inclusion of a risk area associated with this frontal passage. Limited severe potential may also exist for a few hours in the afternoon and early evening over the Upper Mississippi Valley area, as a stronger/reinforcing cold front surges southeastward out of Canada across the Upper Mississippi Valley and Great Lakes region and into central Plains and Upper Midwest overnight. Though only modest moisture -- and thus weak afternoon pre-frontal destabilization -- is expected, low-topped convection is expected during the afternoon across parts of Upper Michigan/Wisconsin and perhaps Minnesota. Strong northwesterly flow aloft would support fast-moving storms, and possibly a risk for damaging winds locally. Again though, this potential appears too limited/uncertain to include a risk area at this time. Day 5, the surging cold front is forecast to shift southeastward into the Northeast/New England, and southward across the Ohio Valley area. Similar to Day 4 potential for low-topped storms farther northwest, convection will likely develop along the front through the afternoon -- particularly across the New England vicinity. However, given the frontal passage the prior day, questions with respect to available moisture -- and thus destabilization potential -- exist at this time. As such, despite the strong front and strong flow aloft, severe risk again appears limited and uncertain, precluding introduction of a risk area for now. The cold front is expected to have moved offshore of New England and the Mid-Atlantic region by the start of Day 6, becoming quasistationary in a west-to-east manner across the Southeast and Mid South, on the southern fringe of a Canadian High settling into the northeastern quarter of the country. While convection will likely occur near and south of this front where moist Gulf air will remain in place, this region will remain well south of the enhanced flow aloft. Therefore, severe risk appears minimal -- and should remain so through the end of the period. ...Goss.. 08/28/2024 = = = 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) .