[BNAWX] Severe Storm Outlook Narrative

Tue Mar 21 16:31:01 CDT 2017

ACUS11 KWNS 212130
SWOMCD
SPC MCD 212130
TNZ000-GAZ000-ALZ000-212300-

Mesoscale Discussion 0304
NWS Storm Prediction Center Norman OK
0430 PM CDT Tue Mar 21 2017

Areas affected...middle TN into northeastern AL and northwest GA

Concerning...Severe Thunderstorm Watch 76...

Valid 212130Z - 212300Z

The severe weather threat for Severe Thunderstorm Watch 76
continues.

SUMMARY...There is high confidence in scattered to widespread wind
damage from a forward-propagating MCS which will yield swaths of
50-70 mph gusts.

DISCUSSION...Radar mosaic and single-site imagery show a maturing
MCS over middle TN which is moving east-southeastward around 40-kt.
Linear extrapolation has the convective system near the GA/AL/TN
tristate area between 23-00z.  Steep lapse rates from the surface to
500-mb (around 8 degrees C/km) will favor a long-lived MCS this
evening.  The combination of appreciable water loading coupled with
horizontal momentum transport via a favorable lower-tropospheric
thermodynamic setup will likely result in swaths of 50-70 mph winds
and scattered to widespread tree damage.

Farther east, hail will be the primary threat with discrete cells
ahead of the line due to ample CAPE in the -10 to -30 degree layer
and sufficient deep-layer shear for severe multicells and transient
supercell structures.

..Smith.. 03/21/2017

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

ATTN...WFO...MRX...FFC...OHX...HUN...

LAT...LON   35038719 36228655 35838490 35148458 34618490 34538557
            35038719

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