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Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 202353
SWOMCD
SPC MCD 202353
MOZ000-ARZ000-210100-

MESOSCALE DISCUSSION 0735
NWS STORM PREDICTION CENTER NORMAN OK
0653 PM CDT MON MAY 20 2013

AREAS AFFECTED...PORTIONS OF SERN MO / NRN AND W-CNTRL AR

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 202353Z - 210100Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...A NEW TORNADO WATCH WILL LIKELY BE REQUIRED DOWNSTREAM
FROM THE EXISTING TORNADO WATCHES TO THE WEST.

DISCUSSION...SURFACE/UPPER AIR ANALYSIS INDICATES A MOIST/VERY
UNSTABLE AIRMASS RESIDES OVER AR AND THE MO OZARKS EARLY THIS
EVENING.  THE 00Z/20 SGF RAOB SHOWS A DEEP/MOIST BOUNDARY LAYER
FEATURING A 14.7 MEAN MIXING RATIO...FAVORABLE FOR SEVERE STORMS.
THE EXPECTED STRENGTHENING OF THE 1-2 KM FLOW OWING TO AN
INTENSIFICATION OF THE LOW LEVEL JET THIS EVENING WILL BECOME MORE
FAVORABLE FOR STORM ROTATION.  AN ADDITIONAL SUPPORTIVE FACTOR
INCLUDES A MORE FAVORABLE CONVECTIVE MODE AS THE BROKEN CONVECTIVE
BAND OF STORMS OVER ERN OK AND SWRN MO WOULD AT LEAST PROVIDE
OPPORTUNITY FOR LONGER TRACK SUPERCELLS TO MAINTAIN THEMSELVES PRIOR
TO UPSCALE GROWTH INTO A LINEAR MCS.  AS A RESULT...SOME SUPERCELL
TORNADO THREAT IN ADDITION TO DMGG WINDS AND LARGE HAIL...WILL
INCREASE THIS EVENING OVER AR AND SRN MO.

..SMITH/CORFIDI.. 05/20/2013

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

ATTN...WFO...PAH...MEG...LSX...LZK...SGF...TSA...

LAT...LON   36629320 37679172 37709026 37229018 35879146 34919272
            34529366 34489443 34879439 36629320

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