Severe storms will be possible this afternoon through late tonight
over the central Gulf Coast states and eventually into far western
Georgia. The risk for a few tornadoes and scattered damaging gusts
will be the primary concerns.
...Central Gulf Coast states into GA...
A mid-level shortwave trough initially over east TX this morning
will quickly move east-northeast into the southern Appalachians and
weaken through the late afternoon/early evening. Amplification of a
larger scale mid-level trough will occur over the central U.S.
during the period as a 500-mb jet streak strengthens to 110 kt by
early Thursday morning over the lower OH Valley. In the low levels,
a convectively augmented frontal zone will initially be draped from
the upper TX coast eastward along the coastal plain of the central
Gulf Coast.
Model guidance indicates the early morning shower/thunderstorm
activity near the Sabine River will move east-northeast across the
lower MS Valley and into AL during midday into the afternoon. A
risk for stronger storms will probably coincide with the southern
portion of this convective cluster on the northern fringe of
appreciable buoyancy closer to the coast. Considerable uncertainty
remains regarding the northward penetration of a warm sector into
central AL as the boundary advances northward as a warm front. As a
result, the northern portion of the Slight Risk across central AL is
accompanied by a significant spread of varying model solutions
(e.g., 00z NAM/NSSL favoring more north and unstable warm sector vs.
a multitude of other model depictions). Nonetheless, it seems
plausible that diurnal destabilization along the Gulf Coast will aid
in the potential for isolated storm development away/south of the
frontal zone across LA/MS/AL. Forecast soundings generally show
500-1000 J/kg MLCAPE with moist boundary layer air and enlarged
hodographs. This likely environment --caveats in terms northward
extent-- will support organized storms. One potential scenario is a
relatively narrow/focused corridor for supercells, both ahead and
embedded within the main convective band, from near the southwest
AL/southeast MS vicinity east-northeast across south-central AL.
Confidence in a greater risk for tornadoes remains uncertain but
will be reassessed in later outlooks. During the evening, the
severe threat will gradually shift from west to east across MS into
mainly AL as the wind profile strengthens. It seems a risk for
severe will probably spread east into the FL Panhandle and western
GA during the overnight in the low CAPE/high shear regime.
