[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 111213
SWOMCD
SPC MCD 111212
TNZ000-KYZ000-ALZ000-INZ000-111345-

Mesoscale Discussion 0030
NWS Storm Prediction Center Norman OK
0612 AM CST Sat Jan 11 2020

Areas affected...Western KY...Middle TN...Northern AL

Concerning...Severe potential...Watch possible

Valid 111212Z - 111345Z

Probability of Watch Issuance...60 percent

SUMMARY...A downstream watch will likely be needed across middle TN
and northern AL, and perhaps as far north as western KY, as the
convective line continues eastward. Primary threats are strong wind
gusts and QLCS tornadoes.

DISCUSSION...Northern portion of the extensive convective line
stretching from southern IN southwestward into southern LA has
recently shown better overall organization, evidenced by a sharper
reflectivity gradient along the leading edge as well as increased
forward speed. This has occurred as the line continues eastward into
a very impressive kinematic environment. Recent mesoanalysis
estimates over 80 kt at 850 mb across far southwest KY and adjacent
northwest TN. Outside of this maximum, mesoanalysis shows a very
large area of 70+ kt at 850 mb. These very strong low-level winds
are supporting 0-1 km storm-relative helicity values from 600 to 800
m2/s2. Additionally, this portion of the line has become more
favorably aligned with the deep layer shear.

The downstream thermodynamic environment is not overly favorable but
dewpoints in the low 60s are now into middle TN with enough
instability anticipated for storm maintenance, particularly given
the very strong vertical shear.  All of these factors suggest the
potential for strong wind gusts and embedded QLCS tornadoes will
persist eastward into northern AL and middle TN. Instability will
lessen with northern extent, but some severe weather threat may
still exist into western KY.

..Mosier/Grams.. 01/11/2020

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

ATTN...WFO...LMK...OHX...HUN...PAH...MEG...

LAT...LON   37048808 37908755 38088688 37538643 34458650 34758808
            37048808
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