11AM Day 2 Convective Outlook for Saturday, February 21. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE NORTHERN GULF COAST STATES TO THE SOUTHERN CAROLINAS .
SUMMARY
Thunderstorms are possible across parts of the eastern Gulf and south Atlantic coast states Saturday and Saturday night. A few stronger storms capable of damaging gusts and a brief tornado are possible.
Discussion
An initially low-amplitude zonal flow regime over the CONUS is forecast to amplify considerably as a shortwave trough over the lower MS Valley deepens while moving into the Southeast. A stalled frontal boundary will be in place from southern North Carolina southwestward toward the northern Gulf Coast. A surface low will develop along this frontal boundary during the day on Saturday in response to the amplifying mid-level trough before moving quickly out to sea by Sunday morning. Sufficient moisture and ascent will likely support widely scattered thunderstorms with some potential for damaging gusts and a brief tornado over parts of the Southeast and southern Carolinas Saturday and Saturday night.
Northeastern Gulf Coast States and the southern Carolinas
Early morning elevated storms should gradually become surface-based as they track east/southeastward ahead of a subtle wave low along the front. South of the front, modest diurnal heating amid mid to upper 60s F dewpoints will result in an environment with up to 500 to perhaps 1000 J/kg of most unstable CAPE. Driven mostly by low-level warm air advection, mid-level lapse rates will remain generally poor (~6.5 C/km) which in combination with the lagged primary upper forcing may tend to limit initial updraft intensity.
As the upper trough amplifies, the low will gradually deepen, potentially serving as a local focus for more sustained convection in southern GA and far southern SC. Long straight hodographs largely parallel to the frontal zone could allow a few more organized line/clusters Saturday afternoon/evening. Given the strong deep-layer shear and some buoyancy from heating, damaging gusts and a brief tornado are possible. Forecast guidance shows a few stronger storms in this region through Saturday evening. Should coverage and overall intensity increase, higher wind probabilities may be needed in future outlooks.
Farther west, the surging front will likely undercut convection across the western flank of the warm sector as the surface low deepens. However, stronger heating and relatively larger buoyancy suggests isolated strong gusts remain possible with any stronger storms able to persist. Convection should gradually diminish as it moves southeastward toward the Gulf Coast and FL Panhandle into early Sunday.