[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 271750
SWOMCD
SPC MCD 271750
WVZ000-OHZ000-VAZ000-KYZ000-TNZ000-INZ000-271915-

Mesoscale Discussion 0863
NWS Storm Prediction Center Norman OK
1250 PM CDT Sat May 27 2017

Areas affected...Portions of central/eastern KY...middle/eastern
TN...southern IN/OH...western WV...and far western VA

Concerning...Severe potential...Watch possible

Valid 271750Z - 271915Z

Probability of Watch Issuance...60 percent

SUMMARY...Large hail and damaging wind threat will increase with
thunderstorms developing along an outflow boundary and stalled front
this afternoon. Watch issuance is possible within the next several
hours.

DISCUSSION...Visible satellite and radar imagery depict an outflow
boundary from earlier convection extending from parts of
south-central KY into northern middle TN. The airmass downstream of
this boundary has destabilized with temperatures warming into the
upper 70s and lower 80s, and dewpoints in the mid to upper 60s.
Steep mid-level lapse rates of 7-8 C/km are supporting MLCAPE
generally 1000-2000 J/kg across this region. A convectively enhanced
mid-level vorticity maximum moving eastward this afternoon will
likely encourage scattered thunderstorms to form along the outflow
boundary over the next several hours. Additional thunderstorms will
likely develop along a stalled front across southern OH into WV. A
belt of strong westerly mid-level winds of 40-50 kt (locally higher)
associated with the low amplitude shortwave trough/vorticity maximum
and a veering wind profile with height is resulting in effective
bulk shear values of 35-55 kt, stronger across KY/TN. This expected
combination of moderate to strong instability with sufficient shear
will support supercell structures, with both a large hail and
damaging wind threat. Eventual growth into clusters/line segments is
probable, with perhaps a greater damaging wind threat later this
afternoon if this occurs.

..Gleason/Hart.. 05/27/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...RLX...MRX...JKL...ILN...LMK...OHX...IND...

LAT...LON   36888250 36058351 35878402 35998493 36258561 36688638
            37108682 37638678 38648654 39088578 39748391 39748265
            39488116 39188102 37888143 37398197 36888250
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