Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 090547
SPC MCD 090547

Mesoscale Discussion 1792
NWS Storm Prediction Center Norman OK
1147 PM CST Fri Dec 08 2017

Areas affected...central through south Florida

Concerning...Severe potential...Watch unlikely

Valid 090547Z - 090645Z

Probability of Watch Issuance...20 percent

SUMMARY...Storms may pose at least a marginal risk for a few locally
strong wind gusts and possibly a brief tornado into the early
morning. At this time, overall threat does not appear sufficient for
a watch, but trends will continue to be monitored.

DISCUSSION...Thunderstorms continue developing along and behind a
southeast-advancing cold front located from near Daytona Beach to
near the Tampa Bay area. The warm sector remains marginally unstable
with weak lapse rates and around 1000 J/kg MLCAPE within an
environment characterized by 35-45 kt effective bulk shear and
modest low-level hodographs. Given the positive orientation of the
upper trough, the deeper forcing for ascent will remain in the post
frontal regime. However, frontal convergence and a weak cap will
likely sustain convection through the early morning hours. Other
storms will persist within pre-frontal warm sector, though overall
tendency has been for this activity to weaken as it moves inland.
Latest HRRR runs indicate some intensification might occur toward
09Z, but other CAMS show an overall weakening trend. Current
thinking is that storms may occasionally develop bowing segments and
marginal supercell structures next several hours with strongest
storms likely in frontal zone. A marginal thermodynamic environment
and poor phasing of the deeper ascent and warm sector will remain
limiting factors for a more robust severe threat. Nevertheless, a
few locally strong to damaging wind gusts and a brief tornado remain
possible in this region through early morning.

..Dial/Grams.. 12/09/2017

...Please see for graphic product...


LAT...LON   27138235 27718170 28508083 27318038 26458088 26018165
            26618197 27138235 is the U.S. government's official web portal to all federal, state and local government web resources and services.