SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1205 AM CST Thu Jan 11 2024
Valid 121200Z - 131200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FRIDAY
AFTERNOON AND INTO FRIDAY EVENING ACROSS PARTS OF EAST CENTRAL AND
SOUTHEASTERN ALABAMA...MUCH OF CENTRAL GEORGIA AND SOUTH CAROLINA
INTO SOUTHERN NORTH CAROLINA...
...SUMMARY...
Severe thunderstorms, with potential to produce high winds and a few
strong tornadoes, are possible across parts of the Southeast Friday
through Friday evening.
...Discussion...
There appears little substantive change in the latest available
ECENS/ECMWF and GEFS concerning the forecast evolution for this
period. Strong surface cyclogenesis is likely to proceed Friday
across the Mississippi Valley through Atlantic Seaboard, as a
vigorous supporting short wave trough pivots northeast of the
southern Great Plains. It still appears that the center of the
growing cyclone will undergo a period of rapid deepening across the
lower Ohio Valley during the day, including minimum surface
pressures falling on the order of 15-20 mb in a 12 hour period,
though the 00Z NAM/03Z RAP take a track to the northwest of the
other guidance into the Great Lakes region through late Friday
night.
Regardless, associated strengthening of deep-layer wind fields
probably will including a developing swath of 90-120+ kt
cyclonic/southwesterly flow at 500 mb across the lower Mississippi
Valley, through portions of the Northeast and Mid Atlantic by the
end of the period. In the 850-700 mb layer, 50-90 kt south to
southwesterly flow is generally forecast to overspread the inland
advancing warm sector.
There remains some uncertainty concerning just how expansive of an
unstable warm sector may develop, with perhaps low-level warming and
moistening becoming sufficient, in the presence of strong forcing
for ascent, for weak boundary-layer destabilization northeast of the
lower Mississippi Valley through parts of the Tennessee and lower
Ohio Valleys during the day.
More substantive low-level moistening is probable off the north
central/northeastern Gulf of Mexico, into the eastern Gulf through
south Atlantic coast states. However, with the mid-level cold pool
forecast to shift north of this region, relatively warm layers
aloft, even in advance of mid-level subsidence warming nosing
east-northeastward across coastal areas, could inhibit
destabilization.
More problematic, concerning the severe weather potential, the NAM
and Rapid Refresh forecast soundings are slow to erode the initially
cool boundary layer, and maintain at least a shallow near surface
stable layer. If this verifies, convective potential will probably
be mitigated. However, a corridor of strong surface pressure falls
still appears likely to develop across the Southeastern Piedmont,
from Alabama through the Carolinas midday Friday through Friday
evening, near the southern periphery of the mid-level height falls.
Associated forcing may contribute to more rapid modification of the
boundary-layer, in the presence of an environment otherwise becoming
conditionally supportive of significant severe weather potential.
Strong to severe thunderstorm development, initiating Thursday night
across the southeastern Great Plains into the lower Mississippi
Valley, may be ongoing at the outset of the period, spreading
east-northeast of the Mississippi River Friday morning, before
perhaps weakening. Renewed thunderstorm intensification is then
expected near/ahead of a developing pre-frontal dryline structure
developing across east central/southeastern Alabama by early
afternoon, particularly near where it intersects a strengthening
frontal zone across the Piedmont. This probably will be maintained
while spreading east-northeastward across Georgia into the Carolinas
by late Friday evening.
Although the evolution of an organized convective cluster still
appears possible, discrete supercell development may remain the
primary convective mode, accompanied by a risk for strong tornadoes.
..Kerr.. 01/11/2024
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