2AM Day 3 Convective Outlook for Sunday, October 19. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE OHIO VALLEY AND APPALACHIANS
SUMMARY
Severe storms with a threat mainly for damaging winds are possible over parts of the Ohio Valley and Appalachians Sunday.
Synopsis
A strong neutral to slightly negative tilt upper trough over the OH Valley and Great Lakes is forecast to continue intensifying as it moves quickly eastward Sunday. At the base of the trough, a 90+ kt jet streak will lift northward into the upper OH Valley and Northeast deepening a surface low over the Great Lakes and eastern Canada. Strong southerly winds ahead of the low will support a modestly moist air mass from eastern OH/KY into western PA and WV. A cold front expected to move eastward with the low will serve as a focus for thunderstorm potential Sunday morning through Sunday evening.
OH Valley and Appalachians
A squall line is likely to be ongoing at the start of the period from central/eastern OH into northern KY ahead of the front and deepening surface low. Strong ascent from the trough/jet streak should maintain this shallow convective line into portions of PA/WV by early afternoon. With upper 50s to low 60s F dewpoints and only modest heating, buoyancy appears limited. However, the strong flow aloft should still support a risk for damaging gusts. Backed flow ahead of the surface low will favor large low-level shear which could support embedded rotation with the potential for a brief tornado or two. Storms will gradually weaken with eastward extent as available buoyancy wanes into the evening.
Central Gulf Coast and the Southeast
At the start of the period, a few storms may be ongoing along the front as it continues east/southeastward across southern MS/AL and western FL. With marginal buoyancy and on the southern fringes of the stronger flow aloft, a few strong wind gusts cannot be ruled out, but convection should weaken through the morning before moving offshore.
The cold front will continues eastward through the remainder of the day with remnant showers and cloud cover likely ahead of it. Still, some heating and destabilization is possible across the Southeast and southern Appalachians. However, weak subsidence is expected over much of the region as the primary upper trough and jet streak begin to lift away to the north. This currently suggests limited redevelopment will occur along the front Sunday afternoon, though there remains substantial uncertainty. While isolated storms cannot be ruled out, confidence remains too low for severe probabilities.