Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Dec 31 2024 19:39:36 ACUS01 KWNS 311939 SWODY1 SPC AC 311938 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0138 PM CST Tue Dec 31 2024 Valid 312000Z - 011200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL APPALACHIANS TO THE MID ATLANTIC... ....SUMMARY... Damaging gusts, isolated hail, and a brief tornado remain possible this afternoon from the central Appalachians into parts of the Mid-Atlantic. ....20z Update... The previous forecast remains valid with minimal changes. The western edge of the Marginal Risk area has been removed from portions of eastern KY and western WV, as the aforementioned upper trough has moved eastward. Weak buoyancy (200-400 J/kg MUCAPE) is present across parts of WV and VA where clear skies have allowed surface temperatures to warm to near 60 F beneath the mid-level cold core. Despite very minimal surface moisture (dewpoints in the 30 to 40s F) steep mid and low-level lapse rates (7-7.5 C/km) will continue to allow for 35-50 kt of 0-3 km flow to mix down to the surface. Several gusts of 45+ kt have been observed with low topped convective bands ahead of and along the cold front. As these storms move eastward, they will continue to pose a risk for damaging winds through the afternoon. Isolated small hail and perhaps a brief tornado also remain possible with any stronger rotating cells, given relatively strong low-level speed shear. See the prior discussion and MCD 2322 for more info. ...Lyons.. 12/31/2024 ..PREV DISCUSSION... /ISSUED 1025 AM CST Tue Dec 31 2024/ ....KY to the Mid Atlantic Region... A potent, negatively-tilted shortwave trough will move from the upper OH Valley into NY/PA today, with an associated 80-100 knot mid-level speed max nosing across the Carolinas. Strong large-scale forcing and low-level warm advection is resulting in sufficient lift for the development of multiple lines/clusters of low-topped convection (some with lightning) across parts of OH/KY/TN/WV. This activity will move quickly eastward through the day across the central Appalachians and into the Mid Atlantic region this afternoon/evening. Forecast soundings show cold mid-level temperatures, resulting in steep lapse rates aloft. This will continue to support a threat of thunderstorms through tonight. Low-level moisture is quite limited, and forecast CAPE values are below 500 J/kg. Nevertheless, low and mid-level wind fields are very strong, which could easily mix down within any more-organized convection. Low-level shear is also strong enough to support updraft rotation (as already noted in a few cells this morning in KY) which could pose a risk of a brief tornado or occasional hail through the period. $$ = = = 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) .