Valid 261300Z – 271200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THROUGH THIS
EVENING FROM EASTERN MS ACROSS AL INTO THE FL PANHANDLE AND WESTERN
GA…
…SUMMARY…
A few strong/severe thunderstorms are possible today across eastern
Mississippi, Alabama, the Florida Panhandle, and western Georgia. A
brief tornado or locally damaging wind gust are the primary threats.
…MS/AL/GA through this evening…
The remnants of tropical cyclone Olga have moved inland across
southeast LA and into south central MS this morning, and there have
been a few measured gusts in excess of 50 kt with the remnant
convective core. In the short term, the 12z Jackson sounding and
WSR-88D velocity data suggest additional potential for strong
gradient gusts and some downward momentum transfer with the deeper
convection near the remnant tropical cyclone core. In the longer
term, the cyclone will continue north-northeastward to IL/IN/Lower
MI by tonight, in advance of a midlevel shortwave trough ejecting
northeastward from northeast TX.
East and southeast of the low, low-topped rotating convection has
been noted this morning across southeast MS, where low-mid 70s
boundary-layer dewpoints are contributing to weak surface-based
buoyancy where 0-1 km SRH is near 400 m2/s2. This overlapping zone
of weak buoyancy and strong low-level shear will tend to develop
north-northeastward toward AL today as the surface cyclone moves
northward and a trailing cold front progresses eastward. However,
the surface cyclone and stronger low-level shear will also develop
away from the tropical moisture source region in time, leaving a
shrinking window of opportunity for rotating storms through the day
and into this evening, which is corroborated by recent HRRR runs and
the HREF. Given that clouds will likely slow surface heating and
lapse rates aloft will remain poor in the warm sector, the overall
tornado and damaging wind threat is expected to remain marginal.
The lingering effects of stronger daytime heating east of the
thicker clouds could allow a few strong storms to persist just ahead
of the cold front this evening into western GA.
..Thompson/Smith.. 10/26/2019
$$