Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 270636
SWOMCD
SPC MCD 270635
ARZ000-LAZ000-TXZ000-OKZ000-270830-

MESOSCALE DISCUSSION 0471
NWS STORM PREDICTION CENTER NORMAN OK
0135 AM CDT WED APR 27 2016

AREAS AFFECTED...PORTIONS AR...NWRN LA...S-CENTRAL THROUGH NE TX.

CONCERNING...SEVERE THUNDERSTORM WATCH 113...

VALID 270635Z - 270830Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 113
CONTINUES.

SUMMARY...EXTENSIVE SQUALL LINE FROM OZARKS ACROSS ARKLATEX TO
PORTIONS S-CENTRAL/SW TX STILL POSES RISK OF SPORADIC DAMAGING GUSTS
NEAR SVR LEVELS.  BRIEF/SMALL QLCS-TYPE TORNADO OR TWO CANNOT BE
RULED OUT OVER NRN AR.  AREAS E OF WW 113 ACROSS AR ARE BEING
MONITORED FOR POSSIBILITY OF ADDITIONAL WW AS CONVECTIVE/INSTABILITY
TRENDS WARRANT.

DISCUSSION...SFC MESOANALYSIS SHOWS OUTFLOW BOUNDARY FROM EARLIER
MCS ARCHING FROM MEM AND SRC AREAS ACROSS NRN AR TO INTERSECTION
WITH SQUALL LINE OVER BARRY COUNTY MO.  OUTFLOW BOUNDARY WILL REMAIN
NEARLY STATIONARY...WITH ONLY MINOR NWD DRIFT POSSIBLE ON ITS WRN
END BEFORE BEING OVERTAKEN BY CONVECTIVE BAND.  ALONG AND S OF
OUTFLOW BOUNDARY...SFC DEW POINTS MID/UPPER 60S F OVER AR AND NE TX
TREND TO LOW-MID 70S F OVER S TX.  BASED ON 00Z RAOBS AND FCST
SOUNDINGS...EML-RELATED CINH IS STRONGER WITH SWWD EXTENT ACROSS
TX...AND 06Z SHV RAOB SHOWS STG CINH WITH THAT LAYER WHOSE WARM AIR
LIKELY IS ADVECTING POLEWARD TOWARD AR.  GRADUAL/NOCTURNAL DIABATIC
COOLING IN FOREGOING WARM SECTOR...S OF OUTFLOW BOUNDARY...WILL
CONTRIBUTE FURTHER TO SBCINH AS WELL.  FOR PAST 2-3 HOURS...MEASURED
GUSTS HAVE BEEN SUB-SVR AT OBS SITES IN OK/AR/TX ACROSS WHICH SQUALL
LINE HAS PASSED.

GIVEN THESE FACTORS...PRIND DAMAGING-WIND RISK GENERALLY WILL LESSEN
WITH TIME EXCEPT WHERE SMALL-SCALE COLD-POOL PROCESSES MAY TRANSFER
MOMENTUM GROUNDWARD.  STILL...FORCED ASCENT AND FAVORABLE BUOYANCY
SHOULD PERMIT ORGANIZED BAND OF CONVECTION TO PERSIST FOR SEVERAL
MORE HOURS...WITH SOME POTENTIAL THAT IT WILL BE NEAR SVR LEVELS
WHEN IT GETS E OF WW OVER AR.  STEEP MIDLEVEL LAPSE RATES SUPPORT
MUCAPE 2000-3000 J/KG OVER MUCH OF WARM SECTOR.  EFFECTIVE-SHEAR
MAGNITUDES RANGE FROM 30-40 KT OVER NRN AR TO 50-60 KT OVER S
TX...WITH NEARLY CONVECTION-PARALLEL MEAN-WIND VECTORS.  THIS WILL
SUPPORT CONTINUED QLCS MODE FAVORING STG/ISOLATED SVR GUSTS WITH
MRGL-SVR HAIL.  BRIEF TORNADO FROM QLCS LEADING-EDGE CIRCULATION
STILL MAY BE POSSIBLE OVER NRN AR ESPECIALLY INVOF OUTFLOW BOUNDARY
WHERE BACKED SFC FLOW AND ENHANCED LOW-LEVEL VORTICITY ARE PRESENT.

..EDWARDS.. 04/27/2016

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

ATTN...WFO...MEG...JAN...LZK...LCH...SHV...TSA...HGX...FWD...
EWX...SJT...

LAT...LON   29790138 30449871 31269668 32859506 33989434 35619405
            36439382 36469130 35999125 34029164 33209199 32249275
            30959454 30009612 29459826 29539952 29790138




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