SPC Dec 9, 2024 0700 UTC Day 2 Convective Outlook

SPC 0700Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1258 AM CST Mon Dec 09 2024

Valid 101200Z - 111200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF CENTRAL AND SOUTH AL...SOUTHWEST GA...AND THE ADJACENT FL
PANHANDLE...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of
central and south Alabama, southwest Georgia, and the adjacent
Florida Panhandle on Tuesday.

...Synopsis...
Deep upper troughing is forecast to extend from central CA into the
Southwest/northern Mexico Tuesday. This troughing will be anchored
by a shortwave trough expected to move from the southern 
High Plains eastward across the southern Plains and Lower MS Valley.
Progression of this shortwave will foster a more neutral tilt to the
parent upper troughing while also significantly strengthening the
mid-level flow through its eastern periphery. A belt of 100-120 kt
500 mb flow will likely extend from AL into the central Appalachians
early Wednesday morning.

A surface low initially near the ArkLaMiss region is expected to
move quickly northeast toward the upper Ohio Valley, with some
guidance showing secondary cyclogenesis later in the period along
the trailing cold front that will move across the Southeast.

...Southeast...
A moderately moist warm sector will precede the front forecast to
move across the region, with dewpoints increasing into the mid 60s
by the afternoon across central AL/GA and the FL Panhandle. Modest
secondary cyclogenesis appears possible along the front as it moves
through central AL and intersects slightly greater returning
low-level moisture. Buoyancy will remain modest, mitigated by poor
lapse rates and relatively warm profiles, but vertical shear will be
strong (i.e. 0-6 km bulk shear greater than 50 kt) and supportive of
organization with any deeper, more persistent updrafts. These deeper
updrafts appear most probable within the warm sector near the
developing secondary surface low (i.e. central/southern AL into
southwest GA and the adjacent FL Panhandle) during the late
afternoon. Any sustained cells/clusters within this environment
could pose a threat of isolated damaging gusts and possibly a
tornado. A gradually narrowing warm sector will likely limit the
northern and eastern extent of the severe threat, though a strong 
storm or two cannot be ruled out from north AL/GA into
middle/eastern TN. 

...GA/north FL in the Carolinas and Outer Banks late Tuesday night
into early Wednesday morning...
A strong south-southwesterly low-level jet is expected to develop
from Georgia through the eastern Carolinas late Tuesday night into
Wednesday morning, in response to the intensifying shortwave trough
moving into the Southeast. Warm-air advection associated with this
jet coupled with strengthening large-scale ascent is expected to
result in increasingly broad area of precipitation across the
region. Surface-based storms appears unlikely within this
environment, but robust wind fields could still support a strong
gust or two.

Greater low-level moisture may advect into the NC Outer Banks
vicinity early Wednesday morning, with low-level and deep-layer
shear increasing across the region as well. Any surface-based storms
could have some severe potential. However, guidance differs on how
far the mid 60s dewpoints penetrate inland, which, given the warm
mid-level temperatures, currently limits the predictability of
surface-based storms.

..Mosier.. 12/09/2024

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