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Severe Storm Outlook Narrative (AC)
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ACUS03 KWNS 240732
SWODY3
SPC AC 240730

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT FRI MAY 24 2013

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF NERN WY / WRN SD /
WRN NEB...

...SYNOPSIS...
THE UPPER PATTERN FOR THE DAY 3 PERIOD IS CHARACTERIZED BY A WRN
U.S. UPPER TROUGH CENTERED OVER THE PACIFIC NW...A MID LEVEL RIDGE
OVER THE CNTRL U.S...AND A SLOW-TO-DEPART CLOSED LOW OVER NEW
ENGLAND.  MODELS HINT AT A LEAD DISTURBANCE MOVING INTO THE CNTRL
HIGH PLAINS BY SUNDAY EVENING AS A WEAK CNTRL HIGH PLAINS LOW
BECOMES ESTABLISHED WITH AN ATTENDANT LEE SURFACE TROUGH/DRYLINE.

...CNTRL AND NRN PLAINS...
EARLY DAY STORMS --PERHAPS ONGOING AT THE START OF THE PERIOD-- MAY
OCCUR INVOF A RESIDUAL NW-SE ORIENTED FRONTAL ZONE OVER THE MID MO
VALLEY REGION.  FORECAST SOUNDINGS SHOW ONLY MARGINAL INSTABILITY
AND MODEST DEEP FLOW AND WOULD SUGGEST THESE STORMS MAY BE
SUB-SEVERE.  ATTENTION FOCUSES WWD OVER THE NRN-CNTRL HIGH PLAINS
LATER IN THE DAY AS STRONG HEATING IS FORECAST TO OCCUR ON THE WRN
EDGE OF MOISTURE LOCATED OVER THE CNTRL-NRN HIGH PLAINS.  A STOUT
EML FEATURING 12-14 DEG C H7 TEMPS FROM THE TX PANHANDLE NWD THROUGH
WRN KS WILL LIKELY LIMIT STORM COVERAGE FROM WRN KS SWD INTO WRN TX
ON THE DRYLINE.  WEAK HEIGHT FALLS BY EVENING OVER THE CNTRL HIGH
PLAINS IN ASSOCIATION WITH AN EJECTING IMPULSE AND GENERALLY
LOWERING HEIGHTS OVER THE NRN PLAINS IN ADVANCE OF A NRN GREAT BASIN
SPEED MAXIMA...WOULD IN TURN BECOME MORE FAVORABLE FOR STORM
DEVELOPMENT.

FORECAST SOUNDINGS FROM PARTS OF WRN KS TOWARDS THE BLACK HILLS SHOW
A VERY STEEP LAPSE RATE ENVIRONMENT WITH SBCAPE RANGING FROM
1500-2500 J/KG EXPECTED NEAR AND E OF THE DRYLINE/LEE TROUGH.  DEEP
LAYER SHEAR WILL LIKELY REMAIN MODEST /25-35 KT EFFECTIVE SHEAR/
OVER THE REGION.  STRONG HEATING WILL ACT IN CONCERT TO WEAKEN AND
LOCALLY ERODE THE CAP WITH ISOLD STORM COVERAGE EXPECTED.  THE LLJ
IS FORECAST TO STRENGTHEN DURING THE EVENING INTO THE
OVERNIGHT...POTENTIALLY ALLOWING SOME OF THE EVENING STORMS TO
LINGER INTO THE OVERNIGHT.

...WRN KS SWD INTO WRN TX...
A FEW DIURNALLY-DRIVEN STORMS MAY FORM BY THE LATE AFTERNOON/EARLY
EVENING HOURS WITHIN A DEEPLY MIXED BOUNDARY LAYER.  SHEAR PROFILES
WILL SUPPORT SOME STORM ORGANIZATION IN THE FORM OF MULTICELLS AND
PERHAPS TRANSIENT SUPERCELL STRUCTURES.  ISOLD DMGG WINDS AND LARGE
HAIL MAY OCCUR WITH THE STRONGEST STORMS.

..SMITH.. 05/24/2013
National Weather Service Weather Forecast Office
