SPC Jan 16, 2024 1300 UTC Day 1 Convective Outlook

[NorthGeorgiaWX]

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0637 AM CST Tue Jan 16 2024

Valid 161300Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN CENTRAL
FLORIDA...

...SUMMARY...
A couple brief tornadoes and isolated damaging winds are possible
this morning into the afternoon over parts of the Florida Peninsula.

...Synopsis...
Broadly cyclonic flow in mid/upper levels will be maintained over
most of the CONUS, as a large cyclone meanders over the southern
Hudson Bay/northern ON region.  A basal shortwave trough was
apparent in moisture-channel imagery from Lower MI across southern
IL to the KS/OK border vicinity.  By 00Z, this perturbation is
expected to elongate further and pivot to northern NY, PA, WV, parts
of KY/TN, and AR.  By 12Z tomorrow, the trough should be over or
just offshore of the coast from New England to northeastern NC,
arching inland to the TRI area. 

At the surface, 11Z analysis showed two primary fronts:
1.  A warm to quasistationary boundary extended from a low near Cape
San Blas southeastward across central FL to a weak low near XMR,
then northeastward approximately along the western part of the Gulf
Stream past the NC Outer Banks.  This boundary should drift
northward over land through much of the day, potentially reaching
north-central FL before being overtaken by the next front.
2.  An Arctic cold front was drawn from the San Blas low
northeastward to another low between HKY-AVL, and southwestward
across the central Gulf.  This front will move offshore of all the
Atlantic Coast by 00Z, except central FL.  By 12Z, the cold front
should clear the entire FL Peninsula and Keys. 

...FL Peninsula...
Widely scattered to scattered thunderstorms are expected to move
roughly eastward across the area, both from the Gulf on either side
of the southern front, and from development over land along and
south of that boundary.  Isolated damaging to severe gusts are
possible -- mainly near and south of the southern front where
surface-based inflow is expected.  A tornado also may occur in the
same regime -- especially closer to the Atlantic Coast where more
potential exists for storm-scale interaction with sea-breeze and/or
favorably aligned outflow boundaries.  

For this outlook cycle, unconditional severe probability bins
overall are kept at marginal categorical level, but appear
nonuniform within that.  Overall, they would appear somewhat greater
to the east and lower to the west, if continuous/heatmap-style
coloring were available.  Activity over the central and especially
eastern parts of the peninsula -- along and south of the southern
then combined front -- will have access to a richly moist boundary
layer with the longest time frame for diurnal destabilization of the
inflow layer.  Somewhat muted diabatic heating through cloud cover
will slow the pace of destabilization, but still yield favorably
uninhibited buoyancy.  With surface dewpoints in the upper 60s to
low 70s F, that heating should offset weak low/middle-level lapse
rates enough to yield MLCAPE generally in the 1000-1500 J/kg range. 


With little change in either heights or height gradient aloft, mid/
upper-level winds and deep shear should remain favorable through the
day, albeit with some decrease as winds veer near the surface. 
Supercell and bowing/clustered modes are possible within the band(s)
of convection.  However, the veering will lead to gradual shrinking/
straightening of hodographs during the period of daytime
destabilization (offsetting factors).  This will make tornado
potential conditional on more storm- to local-scale effects. 
Activity should weaken with southward extent this evening as the
combined boundary moves into a nocturnally stabilizing airmass, with
still more veering of near-surface flow.

..Edwards/Dean.. 01/16/2024

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