SPC 1300Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0733 AM CDT Wed Sep 16 2020

Valid 161300Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
FLORIDA PANHANDLE...NORTHWESTERN FLORIDA...SOUTHEASTERN
ALABAMA...AND SOUTHERN GEORGIA...

...SUMMARY...
As Hurricane Sally moves further inland, it may produce a few
tornadoes over parts of the Florida Panhandle, northwestern Florida,
southeastern Alabama, and southern Georgia through tomorrow morning.

...Synopsis...
In mid/upper levels, an elongated cyclone over the northeast Pacific
will move slowly eastward, causing height falls across parts of the
Pacific Northwest.  Downstream, and past a prominent upper ridge
over the northern Rockies, the northern-stream cyclonic-flow field
across the Great Lakes and vicinity will amplify with height falls. 
This will occur as a strong cyclone digs southeastward across Hudson
Bay.  

Meanwhile, a weak but extensive area of troughing will move slowly
southeastward  across the Mid-South, southern Plains and northern
MX.  These processes will encourage recurvature of what now is
Hurricane Sally northeastward across AL toward western GA through
the period, per NHC forecast.  See NHC advisories for the latest
track/intensity guidance on Sally as the cyclone proceeds deeper
inland.

...Southeast...
See SPC tornado watch 491 and related mesoscale discussions for
near-term tornado threat with Hurricane Sally.  The center of this
hurricane made landfall near Gulf Shores, AL, around 1045Z, and is
forecast by NHC to turn northeastward and accelerate (while still
moving slowly) across southern AL.  

As that occurs, a favorable sector of the eastern semicircle --
south of a persistent/stabilizing precip shield -- will spread/
expand inland and also eastward, in step with that component of
Sally's translational vector.  Some expansion of the supercell-
supporting wind fields just above the surface also is possible
tonight as inland decay of the strongest core winds proceeds, with 
system-relative radial spread of enlarged low-level shear/hodographs
into more of the eastern semicircle, and across southern GA and
perhaps northwestern FL.  Rich inflow-layer moisture and low LCLs
are a given.  The main limiting factor will be buoyancy, though with
sustained favorable inflow off the Gulf amidst a more-southerly
surface wind component, advecting greater theta-e inland across the
FL Panhandle/I-10 corridor today and into portions of southern GA
from late afternoon onward.

..Edwards/Broyles.. 09/16/2020

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