Subj : DAY2SVR: Nws Storm Predic To : All From : Mike Powell Date : Sat Apr 15 2023 08:54:00 ACUS02 KWNS 150602 SWODY2 SPC AC 150601 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Sat Apr 15 2023 Valid 161200Z - 171200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEAST...CAROLINAS...SOUTHERN AND CENTRAL APPALACHIANS...OHIO VALLEY AND SOUTHERN GREAT LAKES... ....SUMMARY... Marginally severe thunderstorms, associated with isolated damaging winds and hail will be possible in parts of the Southeast and Carolinas, northward into the Appalachians and southern Great Lakes ....Ohio Valley/Central Appalachians/Southern Great Lakes... An upper-level low will move northeastward into the western Great Lakes region on Sunday. A belt of strong mid-level flow and large-scale ascent, along the eastern edge of the upper-level system, will translate eastward through the Ohio and Tennessee Valleys. At the surface, a cold front will advance eastward across the Ohio Valley, as a warm front moves into the lower Great Lakes. A pre-frontal trough will extend southward into the central Appalachians. Surface dewpoints ahead of the cold front are forecast to be mostly in the mid 50s to lower 60s F, which will contribute to weak destabilization by midday. As surface temperatures warm, convective development is expected along the instability axis, with storms moving northeastward from the Ohio and Tennessee Valleys into the central Appalachians. NAM forecast soundings along the instability axis at 21Z generally have MLCAPE in the 500 to 1000 J/kg range, along with about 40 knots of 0-6 km shear, and 0-3 km lapse rates near 8.0 C/km. This should be favorable for isolated damaging winds with the stronger multicell line segments. Hail will also be possible. Due to the limited instability, any severe threat is expected to be marginal. ....Southeast/Carolinas... An upper-level trough is forecast to move through the lower to mid Mississippi Valley on Sunday. At the surface, a cold front will advance eastward into the southern Appalachians. Surface dewpoints will likely be in the lower 60s F ahead of the front from central and eastern Georgia into parts of the Carolinas. As surface temperatures warm, MLCAPE is generally forecast to peak in the 500 to 1000 J/kg range. The latest model trends have down-trended on instability, mainly because convection near the Gulf Coast early in the day is forecast to limit destabilization further to north. Although forecast soundings suggest that deep-layer shear will be strong enough for an isolated severe threat, the relatively weak instability should keep any threat marginal. For this reason, have downgraded to marginal across parts of the Southeast and Carolinas for Sunday. ...Broyles.. 04/15/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .