[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 261933
SWOMCD
SPC MCD 261933
ALZ000-TNZ000-MSZ000-ARZ000-262100-

MESOSCALE DISCUSSION 1402
NWS STORM PREDICTION CENTER NORMAN OK
0233 PM CDT SUN JUN 26 2011

AREAS AFFECTED...PORTIONS OF SRN TN...NRN MS...NRN AL...FAR ERN AR

CONCERNING...SEVERE THUNDERSTORM WATCH 555...

VALID 261933Z - 262100Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 555
CONTINUES.

AN ORGANIZED...LEADING-LINE/TRAILING-STRATIFORM MCS EXTENDING FROM
PORTIONS OF MIDDLE TN INTO NRN AL AND FAR NERN MS HAS ASSUMED MORE
OF A BOWING STRUCTURE PER RECENT AREA RADAR IMAGERY. WITH THIS
FEATURE...THE SEVERE THREAT APPEARS TO BE EVOLVING DIFFERENTLY
ACROSS TWO AREAS WITHIN WW555:

1. FOR AREAS WEST OF INTERSTATE 65...SSEWD PROPAGATION OF THE LINE
AND OVERALL CONVECTIVE VIGOR HAS BEEN MORE PRONOUNCED INVOF ITS
INTERSECTION WITH A REMNANT OUTFLOW BOUNDARY FROM AN EARLIER MCS AND
WITH WSW-ENE-ORIENTED HORIZONTAL CONVECTIVE ROLLS EMANATING FROM
N-CNTRL MS. WITH 20-25 KT OF NNWLY EFFECTIVE BULK SHEAR...THIS
ACTIVITY WILL LIKELY POSE AN ENHANCED THREAT FOR DMGG WIND GUSTS
DURING THE NEXT FEW HOURS AS IT MOVES SEWD ACROSS PORTIONS OF NWRN
AL AND FAR NERN MS WHERE A VERY UNSTABLE AIR MASS IS IN PLACE. WEST
OF THE ONGOING CONVECTIVE LINE...THE SEVERE WEATHER THREAT CONTINUES
AS A CUMULUS FIELD BUILDS NEAR A COMPOSITE OUTFLOW BOUNDARY
/RESULTING FROM ONGOING AND EARLIER CONVECTION/...AND ADDITIONAL
CONVECTION ACROSS SRN MO POTENTIALLY PROVIDES SOME IMPACT.
HOWEVER...THIS THREAT WILL LIKELY AVOID FAR SWRN PORTIONS OF THE WW
AREA IN PARTS OF NRN MS...WHERE COUNTIES HAVE BEEN CLEARED UPON
COORDINATION WITH THE MEMPHIS WFO.

2. FOR LOCATIONS ALONG AND EAST OF THE INTERSTATE 65 CORRIDOR... THE
BOWING NATURE OF THE LINE IS RELATIVELY BETTER PRONOUNCED.
HOWEVER...OUTFLOW SURGING AHEAD OF PARENT CONVECTION PER 0.5-DEGREE
REFLECTIVITY FROM THE HYTOP AL RADAR SUGGESTS THAT THIS ACTIVITY MAY
BE AT LEAST SLIGHTLY ELEVATED THUS HINDERING THE THREAT FOR DMGG
WIND GUSTS. HOWEVER...A WELL-DEFINED TRANSITION ZONE FOLLOWING THE
CONVECTIVE LINE REFLECTS A POTENTIALLY STRONG REAR-INFLOW
JET...WHICH COULD YIELD AN ENHANCED THREAT FOR LOCALLY STRONG SFC
WINDS. ADDITIONAL CONVECTION COULD DEVELOP INVOF THE LEADING EDGE OF
THE SEWD-MOVING COLD POOL AND REMNANT OUTFLOW BOUNDARY...AS STRONG
HEATING AMIDST SFC DEWPOINTS FROM THE UPPER 60S TO THE LOWER 70S HAS
ALLOWED MLCAPE VALUES TO REACH 2000 TO 3000 J/KG. HOWEVER...WITH VWP
DATA SUGGESTING A RELAXATION OF THE MID-LEVEL FLOW WITH SWD
DISPLACEMENT FROM THE ONGOING CONVECTIVE LINE...CONVECTION COULD
BECOME INCREASINGLY DISORGANIZED WITH TIME. NEVERTHELESS...DCAPE
VALUES OF 1000-1200 J/KG WILL YIELD A THREAT FOR DMGG WIND GUSTS
WITH WET MICROBURSTS.

..COHEN.. 06/26/2011

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

ATTN...WFO...OHX...BMX...HUN...MEG...

LAT...LON   34139018 35039063 35718998 35748840 35478608 34018552
            33678611 33818771 33888870 34139018


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