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ACUS11 KWNS 221856
SPC MCD 221856

Mesoscale Discussion 0116
NWS Storm Prediction Center Norman OK
1256 PM CST Sun Jan 22 2017

Areas affected...Portions of north FL and extreme southeastern GA

Concerning...Tornado Watch 21...

Valid 221856Z - 222030Z

The severe weather threat for Tornado Watch 21 continues.

SUMMARY...Portions of north FL and extreme southeastern GA are being
monitored for an ongoing increase in the severe-thunderstorm/tornado
potential. While activity presently developing farther west will
more likely pose a greater potential for significant tornadoes later
today as it spreads across the region, the tornado risk may already
be increasing.

DISCUSSION...Convection spreading northeastward from the northeast
Gulf appears to have developed in association with a gravity wave
that advanced across the region. Some of this activity is ingesting
surface-based effective inflow, owing to diabatic heating of the
moist boundary layer. With a modified 18Z Tampa sounding indicating
around 1250 J/kg of MLCAPE and little MLCINH, additional storm
intensification may occur across the area in the short term.

While stronger deep ascent resides farther west, the aforementioned
sounding indicates around 60 kt of deep shear that could support
organized convective structures including supercells. Tornadoes will
be possible, along with damaging winds and severe hail. The greatest
tornado risk will extend across parts of far northeast FL into
adjacent far southeastern GA, where stronger low-level SRH exists in
the recovering/sheltered boundary layer in the wake of earlier
convection (per Jacksonville FL VAD wind profile). Local spatial
extension of the Tornado Watch may be necessary in the short-term,
if intensification of the ongoing activity were to extend over a
broader area, though uncertainty in this scenario persists. A much
more substantial tornado risk will spread across the area later

..Cohen.. 01/22/2017

...Please see for graphic product...


LAT...LON   29388308 30608252 30788161 29948136 28948214 28958272
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