Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 261904
SWOMCD
SPC MCD 261904
OKZ000-TXZ000-262130-

MESOSCALE DISCUSSION 0467
NWS STORM PREDICTION CENTER NORMAN OK
0204 PM CDT SUN APR 26 2015

AREAS AFFECTED...PORTIONS SWRN OK AND EXTREME SERN PANHANDLE OF TX.

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 261904Z - 262130Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...SVR POTENTIAL IS FCST TO INCREASE THROUGH REMAINDER AFTN
ACROSS DISCUSSION AREA...WITH WW ANTICIPATED.

DISCUSSION...SFC MESOANALYSIS SHOWS WAVY SFC FRONT FROM SWRN AR WWD
ACROSS SRN OK...MOVING ERRATICALLY SWD IN SOME AREAS WHILE
QUASISTATIONARY IN OTHERS.  WITH TIME...AND AWAY FROM MODULATING
INFLUENCE OF CONVECTIVE OUTFLOWS..PRIND SFC BAROCLINIC ZONE FRONT
WILL EFFECTIVELY SHIFT/REFORM NWD AMIDST STG SFC HEATING IN CORRIDOR
ALIGNING E-W ACROSS SWRN OK AND INTO SERN PANHANDLE.  THIS PROCESS
ALREADY IS EVIDENT IN STG THETAE GRADIENT NOW ASSOCIATED WITH
DIFFERENTIAL-HEATING ZONE N OF SFC FRONT...WHICH SHOULD BOUND
SFC-BASED EFFECTIVE-INFLOW PARCELS ON N SIDE.  AS AIR MASS BETWEEN
THAT BOUNDARY AND FRONT CONTINUES TO HEAT DIABATICALLY...WITH SFC
DEW POINTS UPPER 50S TO LOW 60S F...EXPECT CINH TO WEAKEN WITH
MLCAPE RISING INTO 1000-2000 J/KG RANGE.  EVEN THOUGH MID-UPPER FLOW
OVER THIS AREA IS CHARACTERIZED BY STG DIFLUENCE WITH WEAKER SPEEDS
THAN FARTHER S AND W...BACKED SFC WINDS HELP TO RENDER FAVORABLE
DEEP SHEAR.  EFFECTIVE-SHEAR MAGNITUDES 40-50 KT ARE EXPECTED AMIDST
EFFECTIVE SRH INCREASING TO 150-300 J/KG RANGE LATE THIS AFTN.

SVR THREAT ACROSS THIS AREA LIKELY WILL BE MAINLY HAIL AT
FIRST...ARISING FROM EITHER IN-SITU DEVELOPMENT ALONG THOSE
BOUNDARIES AND/OR STORMS MOVING NWD AND NEWD FROM WW 119.  TORNADO
THREAT SHOULD INCREASE WITH TIME FOR ANY RELATIVELY
DISCRETE/SUSTAINED CONVECTION AS LOW-LEVEL MOISTURE DOES LIKEWISE.
MAIN UNCERTAINTY INVOLVES CONVECTIVE MODE...WHICH MAY GROW
MESSY/UPSCALE RATHER QUICKLY.

..EDWARDS/MEAD.. 04/26/2015

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

ATTN...WFO...OUN...AMA...

LAT...LON   34019795 34769997 34790050 35170028 35399961 35409867
            35019776 34309746 34029768 34019795



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