Mesoscale Discussion

759 
ACUS11 KWNS 301821
SWOMCD
SPC MCD 301821 
GAZ000-TNZ000-ALZ000-KYZ000-301915-
Mesoscale Discussion 0614
NWS Storm Prediction Center Norman OK
0121 PM CDT Sun Apr 30 2017
Areas affected...northeast Alabama...northwest Georgia...middle
Tennessee into extreme southern Kentucky
Concerning...Severe potential...Watch likely 
Valid 301821Z - 301915Z
Probability of Watch Issuance...80 percent
SUMMARY...Threat for isolated damaging wind and a couple of
tornadoes is expected to increase this afternoon over middle
Tennessee into southern Kentucky. Also additional storms farther
west across north central AL should eventually move into northeast
AL and northwest GA. A ww will likely be issued downstream from ww
182 prior to 19Z.
DISCUSSION...Early this afternoon a band of convection extends
across the western portions of middle TN with more organized
activity farther south into northern AL. The downstream atmosphere
is only marginally unstable with widespread clouds slowing diabatic
warming of the boundary layer. Nevertheless, as temperatures slowly
warm through the 80s F MLCAPE from 500-1000 J/kg will become
sufficient to support at least a modest threat for organized storms
given strengthening deep-layer, unidirectional winds, 30-40 kt
effective bulk shear, and around 200 m2/s2 0-1 km storm relative
helicity based on current storm motions. The convection is expected
to gradually increase or maintain intensity as it develops east next
few hours. Storms may organize with embedded meso-vortices and
bowing segments posing a risk for isolated damaging wind and a
couple of tornadoes.
..Dial/Grams.. 04/30/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MRX...FFC...LMK...OHX...BMX...HUN...PAH...
LAT...LON   34018624 35398694 36268754 36748734 36818630 35928533
            34278488 33568529 34018624