11AM Day 2 Convective Outlook for Friday, February 20. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN GULF COAST STATES
SUMMARY
Scattered thunderstorms, with a few stronger storms capable of hail, are possible Friday night and early Saturday over parts of the Southeast.
Synopsis
Low amplitude but progressive mid-level flow will continue across the southern CONUS Day2/Friday. A shortwave trough and 100+ kt mid-level jet over the southern Great lakes will move quickly eastward and deamplify as subtropical ridging build to the south. A second shortwave, initially over the Desert Southwest will move quickly northeastward reaching the lower MS Valley by early Saturday. A deep surface low over the Great Lakes will gradually fill as its associated cold front surges eastward toward the Atlantic coast. Trailing portions of the front will slow and eventual stall, east to west over portions of the lower MS valley and northern Gulf Coast States.
Thunderstorms are expected to persist from Day1/Thursday east of the surface low early Friday across the eastern Great Lakes and Mid Atlantic vicinity. However, scant low-level moisture and weak buoyancy will preclude severe potential. Scattered storms are expected overnight across portions of the northern Gulf Coast States.
Northern Gulf Coast States .
Mid-level flow is expected to remain quite strong over much of the Southeast Friday as weak subtropical ridging builds in behind the departing eastern shortwave. With weak to neutral mid-level heights, large-scale ascent will be muted for much of the day. Continued southerly flow off the Gulf will support moistening south of the stalled front with dewpoints climbing into the mid 60s F. Low/mid-level warm advection is expected to increase later Friday evening into early Saturday. While the primary ascent from the Southwest US shortwave should remain along the cool side, slight enhancement of the low-level jet is expected to be sufficient for elevated destabilization over parts of northern LA, MS, AL into northern GA and far southern TN. While not overly large, MUCAPE ~ 500 J/kg amid strong deep-layer shear (50+ kt) may allow for a few instances of hail with the stronger elevated storms overnight and early Saturday.
Upper OH Valley
East of the occluding surface low, modest low-level moistening is expected early Friday morning. A narrow plume of relatively higher dewpoints (40s and 50s F) ahead of the surging front could support shallow convection across eastern OH, southwest NY and western PA. Current forecast guidance shows little if any buoyancy. However, given the strong ascent, shallow convective elements are possible along the front. With 100+ kt of mid-level flow, sporadic damaging wind gusts cannot be ruled out should any stronger convective showers develop. Cooler and more stable air farther east into the Mid Atlantic should limit any further wind gust potential later Friday.