[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 090731
SWOMCD
SPC MCD 090730
KYZ000-TNZ000-INZ000-MOZ000-MSZ000-ARZ000-090830-

MESOSCALE DISCUSSION 2091
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT FRI OCT 09 2009

AREAS AFFECTED...PORTIONS CENTRAL/WRN KY....WRN TN TO NRN MIDDLE
TN...EXTREME NWRN MS...SWRN THROUGH NERN AR.

CONCERNING...SEVERE THUNDERSTORM WATCH 761...

VALID 090730Z - 090830Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 761
CONTINUES.

OVERALL SVR POTENTIAL APPEARS TO BE GETTING MORE MRGL/CONDITIONAL
ACROSS THIS CORRIDOR.  THAT SAID...THREAT STILL EXISTS...AND MAY
REMAIN NONZERO AFTER SCHEDULED 8Z WW EXPIRATION...FOR OCCASIONAL
DAMAGING GUST OR BOW/QLCS-PRODUCED TORNADO.  THEREFORE...WE CANNOT
YET RULE OUT ADDITIONAL WW ISSUANCE BEFORE THEN.  MEANWHILE...HEAVY
RAIN WILL REMAIN AT LEAST AS MUCH OF A THREAT WITH RATES COMMONLY
1-2 INCHES/HOUR AND LOCALLY APCHG 3 INCHES/HOUR...WITH TRAINING OF
CORES ACROSS MANY AREAS TO ENHANCE HAZARD.

SFC ANALYSIS SHOWS CONVECTIVE/OUTFLOW BOUNDARY MOVING EWD ACROSS WW
AREA AT RATE OF GENERALLY 10-15 KT...EXCEPT 25-30 KT FOR LINE
SEGMENT/LEWP INVOF IZARD COUNTY AR.  LEADING EDGE WAS EVIDENT FROM
SDF SWWD ACROSS GRAVES COUNTY KY...DUNKLIN COUNTY MO...THROUGH
INFLECTION POINT/LEWP OVER IZARD COUNTY AR...TO CONWAY/POLK COUNTIES
AR AND MCCURTAIN COUNTY OK...AS OF 7Z.  WARM FRONTAL ZONE...E OF
WHICH AIR MASS WAS CONSIDERABLY DRIER AS WELL WITH LARGER
MLCINH...WAS EVIDENT NEAR FTK-GAD LINE...DRIFTING E.
VERY MOIST/HIGH-THETAE AIR MASS AHEAD OF CONVECTIVE BAND AND SW OF
WARM FRONT WILL BE MAINTAINED DURING AND BEYOND NEXT SEVERAL HOURS.
SFC DEW POINTS COMMONLY IN LOW-MID 70S F WILL CONTINUE...ALONG WITH
PW 1.75-2 INCHES...PER GPS READINGS AND MODIFIED RUC SOUNDINGS.
THIS FACTOR...ALONG WITH WAA...WILL KEEP SFC DIABATIC COOLING VERY
GRADUAL IN WARM SECTOR...ALONG WITH VERY SLOW INCREASE IN MLCINH.
MODIFIED RAOBS AND RUC SOUNDINGS INDICATE BOUNDARY LAYER MOISTURE
OFFSETTING WEAK LAPSE RATES ALOFT TO MAINTAIN MLCAPE 800-1500 J/KG.
VERTICAL SHEAR WILL REMAIN FAVORABLE WITH 45-55 KT EFFECTIVE SHEAR
MAGNITUDES.  50-60 KT LLJ WILL EXTEND LOW-LEVEL HODOGRAPHS ENOUGH TO
RESULT IN 0-1 KM SRH AS HIGH AS 500-650 J/KG RANGE ALONG LEADING
EDGE OF CONVECTIVE BOUNDARY...AND ALONG AND SW OF WARM FRONT.

UNFAVORABLE FACTORS...WHICH HAVE DOMINATED SO FAR IN PRECLUDING
KNOWN OCCURRENCE OF TORNADOES OR APPRECIABLE GUST EVENTS -- INCLUDE
UNFAVORABLE LINEAR/ELEVATED CONVECTIVE MODES AND ANAFRONTAL NATURE
OF REGIME...EACH OF WHICH ALSO APPEARS LIKELY TO CONTINUE.
THEREFORE...WHILE SVR PROBABILITIES SHOULD REMAIN VERY
CONDITIONAL...ANY LEWP/BOW FEATURE OR EMBEDDED SUPERCELL
CONSISTENTLY ACCESSING WARM-SECTOR AIR OR INTERACTING WITH WARM
FRONT MAY PRODUCE A QUICK TORNADO.

..EDWARDS.. 10/09/2009

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

ATTN...WFO...LMK...OHX...PAH...MEG...LZK...SHV...

LAT...LON   34699432 35299262 36009165 36588963 37138749 37888646
            38188517 37028575 36118673 35028953 34719032 34249209
            33879406 34699432

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