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ACUS02 KWNS 091737
SPC AC 091735

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1135 AM CST Sat Dec 09 2023

Valid 101200Z - 111200Z


Isolated severe thunderstorms will be possible through Sunday
evening across parts of the Southeast States, mainly in the form of
sporadic damaging winds and a few brief tornadoes.

A highly amplified upper trough will move from the MS Valley toward
the East Coast on Sunday, with a primary embedded speed max ejecting
quickly from the northern Gulf Coast toward the Mid Atlantic. At the
surface, a cold front will push east across the Appalachians during
the afternoon, with the strongest frontal surge across the Southeast
late in the day and into the evening.

Ahead of the cold front, a surface trough will gradually deepen from
MD southwestward to the FL Panhandle, with 40-50 kt southerly 850 mb
flow aiding moistening. Front-parallel winds aloft as well as modest
destabilization will likely lead to scattered storms, with a few
becoming severe across the region.

...Parts of the Southeast and East Coast...
Scattered storms are likely to be ongoing along the front from
southern AL and the western FL Panhandle across northern GA and the
Appalachians Sunday morning, with substantial low clouds across much
of the region. Lack of appreciable heating will generally reduce
available instability, but sufficient boundary layer moisture with
low to perhaps mid 60s F dewpoints will result in a few hundred J/kg
MLCAPE ahead of the cold front. The strongest cooling aloft will
occur behind the boundary, as the upper trough will be quite
amplified with meridional flow aloft.

Storms across the Southeast may eventually become linear as the cold
front accelerates, and this may yield a few damaging gusts.
Low-level shear may also favor isolated supercells with brief
tornado threat, with the main mitigating factor being lack of
heating. Any pockets of strong heating that do develop could yield
mesocale areas of higher potential, and the southeastern area will
be monitored going into the Day 1 period.

Farther north into the Mid Atlantic, boundary layer stability will
likely reduce severe potential to Marginal Risk levels due to the
combination of weak lift/convergence combined with the
cloudy/saturated profiles. Still, strengthening mean winds in the
lowest few km may support strong to perhaps damaging gusts.

..Jewell.. 12/09/2023