[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 161903
SWOMCD
SPC MCD 161902
OHZ000-KYZ000-INZ000-TNZ000-ILZ000-MOZ000-ARZ000-162130-

Mesoscale Discussion 0505
NWS Storm Prediction Center Norman OK
0202 PM CDT Sun Apr 16 2017

Areas affected...Portions of southeastern MO...far northeastern
AR...northwestern TN...KY...southern IL/IN...and southwestern OH

Concerning...Severe potential...Watch unlikely

Valid 161902Z - 162130Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated strong to damaging winds and perhaps marginally
severe hail may occur with thunderstorms across this region through
the afternoon. Watch issuance is unlikely owing to an overall
marginal severe weather threat.

DISCUSSION...Scattered to numerous thunderstorms are ongoing across
this region as of 1855Z along a pre-frontal trough extending from
northeast to southwest across the OH Valley, and with renewed
development in southeastern MO/northeastern AR along part of a MCS
that formed overnight across the southern/central Plains. The
airmass across the Mesoscale Discussion area is weakly unstable per
18Z RAP Mesoanalysis (MLCAPE generally 500-1250 J/kg), and is
forecast to remain so through the remainder of the afternoon owing
to modest 700-500 mb lapse rates (around 6.0-6.5 C/km). Still,
steepening low-level lapse rates with diurnal heating and generally
25-30 kt mid-level flow may promote some strong to damaging winds
with the more robust updrafts. This localized damaging wind threat
may be somewhat greater in association with the eastward moving
cluster of thunderstorms approaching southern IL/western KY. In
addition to the isolated wind threat, there may be a marginal hail
threat with any thunderstorm that can remain mostly discrete along
the pre-frontal trough, as weak effective bulk shear is forecast to
remain somewhat supportive of updraft organization. Overall, the
lack of both stronger instability and shear will likely limit the
magnitude of the severe threat, and watch issuance is unlikely.

..Gleason/Thompson.. 04/16/2017

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

ATTN...WFO...RLX...JKL...ILN...LMK...OHX...IND...PAH...ILX...
MEG...LSX...

LAT...LON   36689089 37879025 38838841 38748648 38768576 39078454
            39318389 39768276 39388225 38578250 38238281 37598404
            37438442 37118580 36308780 35959036 36149095 36689089
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