[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 251959
SWOMCD
SPC MCD 251959
TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-252130-

MESOSCALE DISCUSSION 1385
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SAT JUN 25 2011

AREAS AFFECTED...PORTIONS ERN MO...SRN IL...SWRN INDIANA...WRN
KY...WRN-MIDDLE TN.

CONCERNING...SEVERE THUNDERSTORM WATCH 549...

VALID 251959Z - 252130Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 549
CONTINUES.

CONTINUE WW.  IN ADDITION TO EXISTING CONVECTION AND POTENTIAL FOR
SWD BACKBUILDING...TSTMS MAY MOVE INTO THIS REGION LATE IN WW VALID
TIME FRAME FROM AREAS OF SERN KS OR SWRN MO.  AREAS S AND E OF WW
WILL BE MONITORED FOR POSSIBILITY OF ADDITIONAL ISSUANCE AS TRENDS
WARRANT.

SFC MESOANALYSIS SHOWS SEVERAL POTENTIALLY IMPORTANT FEATURES...
1. MAIN SFC WARM FRONT FROM ERN AL NWWD THROUGH HSV-FAM
LINE...BLENDING WITH
2. OUTFLOW BOUNDARY FROM EARLIER MCS THAT EXTENDS GENERALLY WWD
ACROSS S-CENTRAL/SWRN MO INTO SERN KS AND AREA COVERED BY SPC
MESOSCALE DISCUSSION 1383.  THIS MAY SUPPORT LATER
DEVELOPMENT/MOTION OF CONVECTION INTO SRN MO.
3. SECONDARY/NRN WARM FRONTAL ZONE FROM STL AREA SEWD ACROSS WRN
KY...NEAR SWRN FRINGE OF PERSISTENT BAND OF ELEVATED CONVECTION THAT
STILL MAY POST THREAT FOR ISOLATED/MRGL HAIL AND GUSTS.
4. STG PRESSURE FALLS -- I.E. UP TO ABOUT 7 MB PER 2-HOUR
WAKE-DEPRESSION OVER NERN MO THAT IS BECOMING INCREASINGLY REMOVED
FROM MOST FAVORABLE LOW-LEVEL THERMODYNAMIC REGIME.  AMPLITUDE OF
ISALLOBARIC WAVE ALSO IS NOT AS PRONOUNCED AS EARLIER TODAY...WITH
MUCH WEAKER RISES.

LATTER FACTOR APPEARS TO REDUCE -- BUT DEFINITELY NOT ELIMINATE --
POTENTIAL FOR WELL-ORGANIZED DAMAGING WIND EVENT.  DEVELOPMENT OF
HEAVY-PRECIP SUPERCELLS STILL MAY OCCUR WITH SOME RISK FOR UPSCALE
GROWN AND DEVELOPMENT OF NEW COLD POOL S OF ORIGINAL ONE.  IN
MEANTIME...ANY SUCH STORMS MAY PRODUCE DAMAGING DOWNDRAFT GUSTS AND
LARGE HAIL...WITH TORNADO POTENTIAL MORE CONDITIONAL ON STORM-SCALE
PROCESSES.  DEEP-LAYER SHEAR HAS INCREASED ACROSS WW AREA -- E.G.
EFFECTIVE SHEAR MAGNITUDES 45-50 KT ESTIMATED FROM MODIFIED RUC
SOUNDINGS -- PARTLY IN RESPONSE TO GRADIENT ENHANCEMENT ALOFT S OF
IA MCV AND PARTLY DUE TO BACKING OF NEAR-SFC WINDS BETWEEN WARM
FRONTAL SEGMENTS.  GIVEN STG DIFLUENCE ALOFT AND RELATED
ANTICYCLONIC/SEWD SHIFT OF MID-UPPER FLOW ACROSS WRN KY AND WRN/MID
TN...AND FAVORABLY BUOYANT/MOIST AIR MASS DOWNSHEAR...ANY COMPLEX
THAT CAN DEVELOP OVER WW AREA SHOULD TURN MORE ESEWD/SEWD.

..EDWARDS.. 06/25/2011

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

ATTN...WFO...LMK...OHX...PAH...MEG...LSX...

LAT...LON   38309110 38909000 37688689 35378664 35128748 35338846
            35598909 36228988 36859079 38309110



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