Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 152351
SWOMCD
SPC MCD 152351
OHZ000-INZ000-ILZ000-160215-

Mesoscale Discussion 0067
NWS Storm Prediction Center Norman OK
0551 PM CST Thu Feb 15 2018

Areas affected...southeast Illinois through central and southern
Indiana into southwest Ohio

Concerning...Severe potential...Watch unlikely

Valid 152351Z - 160215Z

Probability of Watch Issuance...20 percent

SUMMARY...At least a marginal risk for a few strong to damaging wind
gusts and a brief tornado will persist through early evening,
initially from southeast IL through central and southern IN and
eventually southwest OH.

DISCUSSION...As of early this evening, a band of convection
including a few thunderstorms, continues to increase from southeast
IL through central IN within zone of low-level warm advection and
isentropic ascent just north of a warm front. A very strong west
southwesterly low-level jet (55-65 kt) coupled with a progressive
mid-upper jet interacting with the warm front and a
southeast-advancing cold front should continue to support convective
development next few hours. Primary limiting factor is weak buoyancy
(MLCAPE around 300 J/kg) with modest low to mid-level lapse rates
relative to the very strong (70+ kt) effective bulk shear. This
suggests updrafts may struggle to remain upright. Nevertheless,
storms may eventually consolidate into line segments, especially as
this activity is intercepted by the southeast-advancing cold front.
Despite limited instability, some storm organization might still
occur within this environment including a few embedded bowing
segments, meso-vortices and some updraft rotation next few hours.

..Dial/Hart.. 02/15/2018

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

ATTN...WFO...ILN...IWX...IND...ILX...

LAT...LON   39578771 39958681 40368559 40488432 40038368 39498392
            39268479 38968650 38808819 39578771



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