SPC AC 120826

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0226 AM CST Wed Dec 12 2018

   Valid 141200Z - 151200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FRIDAY INTO
   FRIDAY NIGHT ACROSS PARTS OF NORTHERN AND CENTRAL
   FLORIDA...SOUTHEASTERN GEORGIA AND THE COASTAL CAROLINAS...

   ...SUMMARY...
   Strong thunderstorms may impact parts of northern and central
   Florida, southeastern Georgia and the coastal Carolinas Friday into 
   Friday night, accompanied by at least some risk for severe weather.

   ...Synopsis...
   Split westerlies will continue to emanate from the mid-latitude
   Pacific, with several embedded amplified waves.  A couple of these
   are forecast to progress through one branch across the Pacific
   Northwest into the Canadian Prairies during this period.  A more
   prominent perturbation within another branch, including a deep
   lower/mid tropospheric cyclone, appears likely to progress more
   slowly, east/northeastward across the lower Mississippi Valley.

   In association with this latter feature, a plume of increasingly
   moist air, emanating from a more substantively modifying boundary
   layer over the central/eastern Gulf of Mexico, appears likely to
   advect into much of the Southeast, with highest moisture content
   overspreading southern and middle portions of the Atlantic Seaboard.
   This may include mid/upper 60s+ surface dew points within the warm
   sector of the cyclone, across much of Florida and perhaps parts of
   adjacent southeast Georgia into coastal areas of the Carolinas.

   Destabilization associated with the moistening, and large-scale
   ascent, is expected to support areas of scattered thunderstorm
   development Friday through Friday night.

   ...Southeast...
   Considerable spread remains evident in model ensemble output, and
   among the various deterministic model output, concerning the
   evolution and progression of the cyclone, including possible
   secondary surface wave development inland across northern Florida
   into the Carolinas.  Even where confidence is greatest concerning
   the most substantive boundary layer moistening, questions remain
   concerning the degree of associated boundary layer destabilization. 
   This may ultimately mitigate the overall severe weather potential,
   but at least isolated severe storms appear possible, particularly
   Friday across parts of northern and central Florida.

   To varying degrees, models indicate that strengthening of lower/mid
   tropospheric wind fields coupled with boundary layer moistening and
   destabilization will precede the inland advance of vigorous
   thunderstorm activity off the northeastern Gulf of Mexico during the
   day Friday.  As this occurs, it appears at least possible that the
   environment may become conducive to organized severe storm
   development, including supercells and a risk for a tornado or two,
   in addition to potential for severe hail and wind.

   ..Kerr.. 12/12/2018

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