[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 150051
SWOMCD
SPC MCD 150050
GAZ000-TNZ000-ALZ000-MSZ000-150315-

MESOSCALE DISCUSSION 2061
NWS STORM PREDICTION CENTER NORMAN OK
0750 PM CDT SUN OCT 14 2012

AREAS AFFECTED...PORTIONS CENTRAL/ERN MS...WRN/NRN AL...SERN
TN...NWRN GA.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 150050Z - 150315Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...INCREASE IN TSTM COVERAGE IS LIKELY DURING NEXT 3-4 HOURS
ACROSS DISCUSSION AREA...PRIMARY MODE BEING QUASI-LINEAR AND
MULTICELLULAR.  ACTIVITY WILL IMPINGE ON WARM-SECTOR PARAMETER SPACE
INDICATING MRGL DAMAGING-WIND POTENTIAL.  STORM-SCALE PROCESSES ALSO
MAY AUGMENT AMBIENT LOW-LEVEL SRH/VORTICITY ENOUGH FOR BRIEF
TORNADO...HOWEVER THAT THREAT IS VERY CONDITIONAL AND SHOULD
DIMINISH WITH TIME AFTER ABOUT 03Z.

DISCUSSION...SFC ANALYSIS AT 00Z SHOWED COLD FRONT FROM SRN INDIANA
SWWD ACROSS SERN AR.  BULK OF CONVECTION SHOULD REMAIN AHEAD OF COLD
FRONT..IN MESOSCALE ZONES OF ASCENT ALIGNED GENERALLY
SW-NE...SLIGHTLY LEFTWARD OF MEAN-WIND AND DEEP-SHEAR VECTORS.  VWP
DATA...RAOBS AND MODIFIED FCST SOUNDINGS SUGGEST PEAK EFFECTIVE
SHEAR MAGNITUDES IN 35-40 KT RANGE...WITH POCKETS OF 150-300 J/KG
EFFECTIVE SRH OVER PORTIONS CENTRAL/NERN MS AND NRN AL...SUPPORTING
TRANSIENT SUPERCELL STRUCTURES WITH EITHER DISCRETE OR EMBEDDED
TSTMS...LATTER HAVING OCCURRED DURING LAST HOUR OVER MONROE COUNTY
MS W CBM.  SFC AIR MASS DRIES WITH EWD EXTENT ACROSS MOST OF
AL...THOUGH MOIST ADVECTION/TRANSPORT BENEATH 30-40 KT LLJ WILL
OFFSET THAT FACTOR TO SOME EXTENT AHEAD OF APCHG CONVECTION.
MODIFIED JAN/BMX RAOBS SUGGEST SFC DEW POINTS UPPER 60S TO LOW 70S F
OVER MOST OF MS AND WRN AL WILL OFFSET WEAK DEEP-LAYER LAPSE RATES
ENOUGH TO YIELD MLCAPE IN 500-1000 J/KG RANGE...DECREASING
CONSIDERABLY IN AREAS OF LOW-MID 60S F DEW POINTS.  BUOYANCY SHOULD
DIMINISH ONLY GRADUALLY WITH TIME IN AREAS OF HIGHER DEW
POINTS...KEEPING LIFTED PARCELS EFFECTIVELY SFC-BASED THROUGH MUCH
OF THIS EVENING.  HOWEVER...LACK OF BOTH STRONGER CAPE AND GREATER
DEEP SHEAR SHOULD LIMIT ORGANIZATION OF ANY SVR THREAT.
ACCORDINGLY...UNCONDITIONAL SVR WIND POTENTIAL LIKELY WILL BE
MAINTAINED AT 5% IN UPCOMING SPC DAY-1 OUTLOOK UPDATE.

..EDWARDS/HART.. 10/15/2012

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

ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MOB...MEG...JAN...

LAT...LON   32458732 32138827 31698917 31489008 32019074 32779077
            33129054 33548950 34168797 34638723 35508614 35518509
            34868471 33748532 33008637 32458732



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