[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 281934
SWOMCD
SPC MCD 281933
KYZ000-TNZ000-INZ000-282100-

Mesoscale Discussion 0578
NWS Storm Prediction Center Norman OK
0233 PM CDT Fri Apr 28 2017

Areas affected...Middle TN...Central KY

Concerning...Severe potential...Tornado Watch likely

Valid 281933Z - 282100Z

Probability of Watch Issuance...80 percent

SUMMARY...All modes of severe, included tornadoes, are possible
across the region this afternoon and evening. A tornado watch will
likely be needed by 21Z to cover this potential severe threat.

DISCUSSION...Airmass across the region continues to modify as
low-level moisture advects northward. Mid 60s dewpoints have now
reached southern portions of middle TN with mid 50s as far north as
northern central KY. Visible satellite shows an increasingly
agitated cumulus field from central KY southward into middle TN. The
cu field farther south into northern AL is flatter, confirming a
more stable airmass across this area. Visible satellite imagery also
reveals an area of more dense cloud cover, arching from the ongoing
cluster of storms across southern IL through southwest KY and into
middle TN. This band appears to be coincident with a subtle
shortwave trough and will likely act as the impetus for new
convective initiation or intensification of the ongoing storms
currently across southern IL once the downstream airmass is
sufficiently destabilized. Once convection initiation occurs, the
environment, which will be characterized by MLCAPE on the order of
2000 J/kg and strong 0-6 km bulk shear around 60 kt, will be
supportive of supercells capable of all modes of severe, including a
few tornadoes. A tornado watch will likely be needed to cover this
potential severe threat.

..Mosier/Grams.. 04/28/2017

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

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

LAT...LON   37898651 38678460 37978385 35728437 35688663 37898651
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