Severe Storm Outlook Narrative (AC)
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140
ACUS11 KWNS 282010
SWOMCD
SPC MCD 282009
ILZ000-MOZ000-282215-

MESOSCALE DISCUSSION 0771
NWS STORM PREDICTION CENTER NORMAN OK
0309 PM CDT SAT MAY 28 2016

AREAS AFFECTED...PORTIONS OF S CNTRL THROUGH NE MISSOURI INTO W
CNTRL ILLINOIS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 282009Z - 282215Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...AN INCREASE IN STRONG TO SEVERE THUNDERSTORM ACTIVITY
APPEARS POSSIBLE THROUGH LATE AFTERNOON...WITHIN A CORRIDOR ACROSS
SOUTH CENTRAL THROUGH NORTHEAST MISSOURI AND WEST CENTRAL ILLINOIS.
THIS MAY REMAIN MOSTLY WEST AND NORTH OF ST. LOUIS.

DISCUSSION...CONVERGENCE ALONG A PERSISTENT LOW-LEVEL CONFLUENCE
ZONE APPEARS TO BE SUPPORTING A GRADUAL INITIATION OF THUNDERSTORM
DEVELOPMENT...WHICH SEEMS LIKELY TO INCREASE INTO AND THROUGH PEAK
LATE AFTERNOON BOUNDARY LAYER INSTABILITY.  THIS LOW-LEVEL BOUNDARY
EXTENDS ROUGHLY FROM THE INTERSTATE-44 CORRIDOR OF SOUTH CENTRAL
MISSOURI THROUGH AREAS WEST AND NORTH OF THE ST. LOUIS METROPOLITAN
AREA.

AIDED BY STEEPENING LOWER/MID TROPOSPHERIC LAPSE RATES WITH
INSOLATION BENEATH A NEARBY MID-LEVEL THERMAL TROUGH AXIS...MIXED
LAYER CAPE NOW APPEARS MODERATELY LARGE...ON THE ORDER OF 2000 J/KG.
DEEP LAYER SHEAR IS RATHER MODEST...BUT SOUTHWESTERLY MEAN AMBIENT
FLOW AROUND 30-40 KT MAY CONTRIBUTE TO THE RISK FOR POTENTIALLY
DAMAGING WIND GUSTS APPROACHING OR EXCEEDING SEVERE LIMITS AS STORMS
INCREASE/INTENSIFY LATE THIS AFTERNOON.

UNTIL THEN...MARGINALLY SEVERE HAIL MAY BE THE PRIMARY SEVERE HAZARD
IN STRONGER INITIAL STORM DEVELOPMENT.  STORM MOTIONS SHOULD BE
LARGELY TO THE NORTHEAST...WITH ONLY A SLOW EASTWARD PROGRESSION OF
THE GENERAL AREA OF CONVECTIVE DEVELOPMENT THROUGH EARLY EVENING.

..KERR/CORFIDI.. 05/28/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...ILX...LSX...DVN...SGF...

LAT...LON   37369324 38159242 39109178 40179146 40539101 40129028
            38519101 36899258 36999338 37369324




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