SPC Jan 6, 2024 0830 UTC Day 3 Severe Thunderstorm Outlook

[NorthGeorgiaWX]

SPC 0830Z Day 3 Outlook

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0218 AM CST Sat Jan 06 2024

Valid 081200Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MONDAY THROUGH
MONDAY NIGHT ACROSS PARTS OF SOUTHEAST TEXAS...SOUTHERN
LOUISIANA...SOUTHERN MISSISSIPPI...SOUTHERN ALABAMA INTO THE WESTERN
FLORIDA PANHANDLE...

...SUMMARY...
Severe thunderstorms, accompanied by a risk for damaging wind gusts
and tornadoes, are possible across parts of southern Louisiana and
southern Mississippi into southern Alabama and the Florida Panhandle
by late Monday night.

...Synopsis...
As initially amplified ridging, within the prevailing split
mid/upper flow over the eastern mid-latitude Pacific, is suppressed
further by another vigorous short wave trough approaching the
Pacific Northwest, a significant evolving downstream trough is
forecast to turn east of the Rockies through this period.  Models
indicate that it will take on a more neutral tilt, and come in
better phase with another perturbation within a belt of westerlies
emanating from the subtropical eastern Pacific, as it progresses
across the southern Great Plains Monday night.

At least modest surface cyclogenesis may already by ongoing across
the Texas Panhandle vicinity by Monday morning.  However, there is
increasing spread evident within the latest model output concerning
subsequent developments across Oklahoma into the Ozark Plateau/Mid
South vicinity by early Tuesday.  A secondary surface low may
develop across and north-northeast of the upper Texas coastal plain
late Monday afternoon and evening.  It is unclear whether this will
merge with the primary cyclone Monday night.  But, the evolution of
a broad and deep primary surface cyclone still appears likely, late 
Monday night through Tuesday.

Low-level moisture return off a modifying boundary over the northern
Gulf of Mexico may contribute to considerable cloud cover and
precipitation across and inland of coastal areas.  Forcing for
ascent associated with the subtropical perturbation, aided by
low-level warm advection, may contribute to considerable
thunderstorm activity near/offshore of upper Texas into central Gulf
coastal areas prior to the inland advance of an unstable warm sector
boundary layer.  Still, the inland advection of mid 60s+ surface dew
points across mid/upper Texas into Louisiana coastal areas appears
probable Monday into Monday evening, and across at least
southeastern Louisiana, southern Mississippi, southwestern Alabama
and the western Florida Panhandle by late Monday night.  Models
continue to suggest that this will be sufficient to support
mixed-layer CAPE on the order of 500-1000 J/kg.

...Gulf Coast vicinity...
The extent of the organized severe weather potential across
mid/upper Texas into Louisiana coastal areas Monday afternoon and
evening, and the potential for hail in elevated convection farther
inland, remain at least somewhat unclear.  Much may depend on
sub-synoptic forcing, but with inland spread of a destabilizing warm
sector, there probably will be at least a window of opportunity for
scattered boundary-layer based convection, including supercells, in
an environment conditionally conducive to large hail and tornadoes.

The most significant severe weather potential still seems likely to
await the development of the stronger dynamic forcing for ascent,
and related rapid surface cyclone deepening, which may impact parts
of southeastern Louisiana and southern Mississippi into southern
Alabama and the western Florida Panhandle by late Monday night, if
not earlier.  Inland boundary-layer destabilization coupled with
intensifying wind fields, including south to southwesterly flow of
50-70+ kt in the 850-700 mb layer, could contribute to an
environment potentially supportive of strong tornadoes.  This may
accompany the evolution of both discrete supercells and an
organizing line or cluster of storms prior to 12Z Tuesday.

..Kerr.. 01/06/2024

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