SPC MD 1703


MD 1703 Image

Mesoscale Discussion 1703
NWS Storm Prediction Center Norman OK
0654 AM CST Sun Dec 09 2018

Areas affected...Portions of the northern/central FL Peninsula

Concerning...Severe potential...Watch unlikely 

Valid 091254Z - 091500Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated strong/gusty winds and perhaps a tornado may
occur with storms moving eastward from the Gulf of Mexico this
morning. Watch issuance is unlikely at this time.

DISCUSSION...A broken line of thunderstorms ahead of a cold front
has intensified over the eastern Gulf of Mexico over the past couple
of hours. Strong low-level warm and moist air advection ahead of
this line along with modest diurnal heating should allow for some
destabilization across parts of the northern/central FL Peninsula
this morning. Recent surface observations across this region
indicate dewpoints have generally increased into the upper 60s, and
MLCAPE of 500-1000 J/kg should develop through mid-morning. The
strongest mid-level flow associated with a southern-stream shortwave
trough over MS/AL/TN will likely remain north of the warm sector in
FL. But, there will still be considerable veering and strengthening
of the low/mid-level winds based on RAP/HRRR forecast soundings.
40-50 kt of effective bulk shear will support updraft rotation with
supercells embedded within the line, and the KTBW radar has shown
some recent mid-level rotation with a couple of these cells
offshore. Isolated strong to perhaps damaging winds should be the
main threat with this convection as it moves quickly eastward this
morning and low-level lapse rates modestly steepen. A tornado cannot
be ruled out over the next couple of hours when hodographs will have
maximum curvature owing to a 35-40 kt low-level jet. Still, tendency
will be for instability to remain weak/marginal owing mainly to poor
mid-level lapse rates, and the overall severe threat will probably
remain too isolated to warrant watch issuance.

..Gleason/Guyer.. 12/09/2018

...Please see www.spc.noaa.gov for graphic product...


LAT...LON   27708173 27258189 26988213 26948239 27148257 27538284
            27878294 28178290 28408275 28608271 28808269 29048249
            29218230 29158197 28878177 28328169 27708173 

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