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Mesoscale Discussion 11
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   Mesoscale Discussion 0011
   NWS Storm Prediction Center Norman OK
   1259 PM CST Mon Jan 02 2017

   Areas affected...Portions of east-central/southeastern
   AL...western/central GA...FL Panhandle.

   Concerning...Severe potential...Watch possible 

   Valid 021859Z - 022100Z

   Probability of Watch Issuance...40 percent

   SUMMARY...A destabilizing air mass ahead of strong-severe convection
   in WW 3 may compel additional WW issuance in the next 1-2 hours,
   mainly near and south of a warm-frontal zone described below.

   DISCUSSION...Surface mesoanalysis located two primary baroclinic
   zones at 18Z, associated with these boundaries:
   1.  Quasistationary damming/wedge front located from central SC to
   central GA than arching northwestward over middle TN;
   2.  Marine/warm front, intermittently diffused by convection, from
   coastal SC to south-central GA, southern AL, and southern MS.  This
   boundary will continue to move slowly northward across southeastern
   AL and southwestern GA before being overtaken by convection later
   this afternoon into evening, and some parts of this front will merge
   with the other one over central/northern GA.  Between the two
   boundaries, a transition zone exists wherein boundary-layer theta-e,
   surface dew points, PW and MLCAPE diminish northward, across
   south-central AL and southwestern GA.  This transition zone will
   shift slowly northward with time, in step with the surface warm
   front to its south.  The northern portion of a wavy, strong-severe
   thunderstorm cluster now over east-central through southwestern AL
   will outrun the associated destabilization; its severe threat will
   diminish into northwestern GA.  However, the remainder of the band
   appears to be getting better organized -- a trend likely to continue
   given the warm-sector destabilization underway that is related to
   both patchy areas of favorable insolation and to boundary-layer warm

   Deep shear already is favorable across this area, with
   effective-shear magnitudes generally 40-50 kt and supercell-favoring
   SRH maximized near those fronts.  Deep shear may increase slightly
   through this evening inland, as the shortwave trough now ejecting
   northeastward out of east TX enhances height gradients aloft. 
   Meanwhile the large-scale lift associated with that trough's DCVA
   regime, as well as the coupled-upper-jet UVV field and low-level
   warm advection, will encourage convective maintenance both with the
   existing activity and any newer, relatively discrete storms that can
   form in the weakly capped warm sector.

   ..Edwards/Weiss.. 01/02/2017


   LAT...LON   32028690 32528749 33048649 33178550 33038479 33018388
               32668224 31978290 30918475 29988547 30288597 30458675
               31308656 32028690 

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