Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 090116
SPC MCD 090116

Mesoscale Discussion 1791
NWS Storm Prediction Center Norman OK
0716 PM CST Fri Dec 08 2017

Areas affected...central Florida

Concerning...Severe potential...Watch possible

Valid 090116Z - 090345Z

Probability of Watch Issuance...60 percent

SUMMARY...Some increase in severe threat might occur this evening
into the overnight over central Florida. Primary threats will be a
few locally strong to damaging wind gusts and perhaps a couple of
tornadoes. Trends will continue to be monitored for a possible WW.

DISCUSSION...This evening a quasi-stationary front extends from the
Gulf Stream southwest across north central FL to about 70 miles
north of Tampa Bay where it transitions to a cold front. This front
will begin to accelerate southeast as a weak surface low develops
over the Gulf stream. The 00Z evening RAOB data from Tampa and
Melbourne indicate weak lapse rates, but around 1000-1200 J/kg
MLCAPE supported by a very moist boundary layer. Storms continue
developing along NW-SE oriented front with the stronger cells just
offshore and northwest of the Tampa area. Radar trends indicate
modest organization with some bowing segments and marginal supercell
structures including weak mid-level updraft rotation. Despite weak
forcing aloft, a persistent southwesterly low-level jet and
southeast acceleration of the front might contribute to some
increase in intensity this evening or overnight. Additional storms
developing offshore within a pre-frontal convergence band could also
move inland. The kinematic environment will remain favorable for
organized storms. However, given the limiting factors including loss
of daytime heating, weak forcing aloft and a modest thermodynamic
environment, confidence in a more robust severe risk is not
particularly high. Therefore any watch issuance will ultimately
depend on convective trends.

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

...Please see for graphic product...


LAT...LON   26588207 27638268 28388258 28808205 29108120 28728078
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