[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 161954
SWOMCD
SPC MCD 161954
KYZ000-INZ000-TNZ000-ILZ000-MOZ000-162130-

MESOSCALE DISCUSSION 0484
NWS STORM PREDICTION CENTER NORMAN OK
0254 PM CDT TUE APR 16 2013

AREAS AFFECTED...FAR SRN IL...IND AND PARTS OF WRN AND CENTRAL KY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 161954Z - 162130Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...POTENTIAL EXISTS FOR ADDITIONAL TSTM DEVELOPMENT THIS
AFTERNOON INTO THE EARLY EVENING ACROSS PARTS OF THE LOWER OH/TN
VALLEYS.  IF A CLUSTER OF STORMS DEVELOPS...THEN A WATCH MAY BE
NEEDED.

DISCUSSION...SURFACE ANALYSES INTO THE MID AFTERNOON INDICATED THE
BOUNDARY IN FAR SRN IL HAD BEGUN TO MOVE NWD...WHILE THE NEWD
EXTENSION OF THIS FRONT INTO SRN IND AND CENTRAL OH REMAINED MORE OF
COLD FRONT WITH GRADUAL ESEWD MOVEMENT. A RELATIVELY NARROW CORRIDOR
OF INSTABILITY HAS DEVELOPED ALONG AND S OF THE FRONTAL ZONE FROM AR
INTO FAR SRN IL...WRN TN AND ACROSS MUCH OF KY WITH MLCAPE RANGING
FROM 1000-2000 J/KG. ALTHOUGH AREA WSR-88D VWP DATA INDICATED
GRADUAL WEAKENING OF LOW LEVEL WINDS...THE SRN EXTENT OF STRONGER
WLY MIDLEVEL WINDS OVER IL TO OH AND SOME BACKING OF LOW LEVEL WINDS
HAVE RESULTED IN STRENGTHENING EFFECTIVE BULK SHEAR THIS AFTERNOON
ACROSS THE DISCUSSION AREA.

WHILE THE CAPE/SHEAR PARAMETER SPACE FAVORS ORGANIZED STRONG TO
SEVERE STORMS...THERE REMAINS SOME UNCERTAINTY WITH THE OVERALL
EVOLUTION OF THE CURRENT STORMS IN FAR SRN IL TO FAR NWRN TN...AND
THE NUMBER OF ADDITIONAL STORMS THAT COULD DEVELOP DURING THE NEXT
SEVERAL HOURS.  THIS REGION RESIDES WITHIN HEIGHT RISES WHICH MAY
TEND TO BE THE PRIMARY FACTOR INHIBITING GREATER CONVECTIVE COVERAGE
AND SUSTAINABILITY OF UPDRAFTS.  THE LAST SEVERAL RUNS OF THE HRRR
SUGGEST WEAKENING INHIBITION ACROSS THIS REGION WILL CONTINUE TO
SUPPORT TSTM DEVELOPMENT...THOUGH THERE REMAINS NO CLEAR SIGNAL FOR
GREATER ORGANIZATION INTO CLUSTERS.

..PETERS/KERR.. 04/16/2013

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

ATTN...WFO...ILN...LMK...OHX...IND...PAH...MEG...

LAT...LON   37148940 38008803 38868617 39038547 38058467 36788536
            36328681 36158932 37148940



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