[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 021920
SWOMCD
SPC MCD 021920
KYZ000-TNZ000-ALZ000-MSZ000-022115-

MESOSCALE DISCUSSION 1861
NWS STORM PREDICTION CENTER NORMAN OK
0220 PM CDT SUN SEP 02 2012

AREAS AFFECTED...PORTIONS CENTRAL KY...MIDDLE-SWRN TN...NWRN
AL...NRN MS.

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 021920Z - 022115Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...BOUNDARY-LAYER DESTABILIZATION IS FCST TO CONTINUE FOR A
FEW MORE HOURS ALONG/AHEAD OF CONFLUENCE ZONE OUTLINED BELOW...IN
SERN QUADRANT OF REMAINS OF ISAAC.  AMIDST AT LEAST MRGL LOW-LEVEL
SHEAR.  THIS WILL RESULT IN FAVORABLE ENVIRONMENT FOR SMALL
BOWS...EMBEDDED MESOCYCLONES IN QUASI-LINEAR SEGMENTS...AND A FEW
SMALL/DISCRETE SUPERCELLS.  A FEW TORNADOES AND DAMAGING GUSTS ARE
POSSIBLE.

DISCUSSION...SFC MESOANALYSIS SHOWS CONFLUENCE LINE FROM NEAR
SRC-NQA-BWG-25 S FTK.  NRN PORTION OF THIS FEATURE IS TRANSLATING
EWD ABOUT 10 KT...WHILE SRN PORTION OVER TN REMAINS QUASISTATIONARY.
AIR MASS NW OF THIS LINE WAS DRIER FROM SFC-500 MB...BASED ON RAOB
AND SFC ANALYSES...AND CONTAINED MORE VEERED DEEP-LAYER FLOW.
MEANWHILE SFC DEW POINTS LOW-MID 70S F AND PW 2-2.25 INCHES WERE
COMMON TO ITS SE.  LOW-LEVEL SRH AND BUOYANCY EACH DIMINISH WITH NWD
EXTENT ACROSS KY.  ALTHOUGH VIS IMAGERY INDICATES THIS AREA STILL IS
COVERED BY BKN-OVC CLOUD COVER...SUFFICIENT BREAKS AND ADVECTION OF
DIABATICALLY HEATED BOUNDARY-LAYER AIR FROM SW SHOULD BE SUFFICIENT
TO MINIMIZE MLCINH THROUGH REMAINDER AFTN.  MODIFIED RAOBS AND FCST
SOUNDINGS SUGGEST PLUME OF MLCAPE 500-1500 J/KG ALONG AND E OF
CONFLUENCE LINE FROM NRN MS TO SERN KY.  THOSE SOURCES...ALONG WITH
VWP INDICATE EFFECTIVE SRH 150-250 J/KG FROM MID TN/AL BORDER NE MSL
TO CENTRAL KY ABOUT HALFWAY BETWEEN GLW-LEX.  MORE VEERED/WLY
COMPONENT OF SFC WINDS LEAD TO SMALLER HODOGRAPHS SWWD ACROSS NRN MS
AND SWRN TN...BUT WITH SOME INCREASE IN LOW-LEVEL SHEAR POSSIBLE
THIS EVENING.  VIS IMAGERY ALSO SHOWS DEEPER CONVECTIVE ELEMENTS
DEVELOPING OVER SERN TN...NRN MS AND NWRN AL THAT COULD MOVE INTO
MORE FAVORABLE ENVIRONMENTS WITH TIME.

..EDWARDS/CORFIDI.. 09/02/2012

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

ATTN...WFO...JKL...LMK...OHX...HUN...MEG...

LAT...LON   35398990 35878802 36918663 37878544 37808473 37138459
            35918561 34768699 34598943 35398990



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