SPC AC 250100

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0800 PM CDT MON JUN 24 2013

   VALID 250100Z - 251200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE GREAT
   PLAINS...NRN HIGH PLAINS AND MID-MO VALLEY...

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE OH VALLEY
   AND SRN GREAT LAKES...

   ...OH VALLEY/SRN GREAT LAKES...
   A VERY WELL-ORGANIZED LINEAR MCS IS MOVING QUICKLY EWD ACROSS NRN
   IND AND EXTENDS SWWD INTO ERN IL. SFC DEWPOINTS AHEAD OF THE LINE
   ARE IN THE UPPER 60S AND LOWER 70S F WITH MLCAPE ESTIMATED IN THE
   1000 TO 2000 J/KG RANGE. IN ADDITION...A PRONOUNCED 700 MB JET OF 50
   TO 65 KT IS LOCATED JUST BEHIND THE BOWING CONVECTIVE SYSTEM. THIS
   ALONG WITH THE INSTABILITY SHOULD SUPPORT THE MCS FOR A FEW MORE
   HOURS...MOVING INTO NRN AND CNTRL OH. A FORWARD SPEED OF 50 KT ALONG
   WITH LOW-LEVEL LAPSE RATES GREATER THAN 7.5 C/KM SHOULD MAKE THE
   LINE VERY EFFICIENT AT PRODUCING DAMAGING WIND GUSTS. HAVE ADDED A
   30 PERCENT WIND DAMAGE PROBABILITY CONTOUR ACROSS NRN IND AND NW OH.
   THE MAIN QUESTION IS...HOW FAR CAN THE LINE MCS GO TO THE EAST.
   OBJECTIVE ANALYSIS SUGGESTS THAT INSTABILITY DROPS OFF ACROSS FAR
   ERN OH INTO WRN PA WHERE SFC DEWPOINTS ARE ONLY IN THE LOWER 60S F.
   THE LINE COULD BE MAINTAINED INTO THIS AREA BUT MAY WEAKEN ACROSS
   WRN PA. FOR THIS REASON...HAVE EXTENDING THE SLIGHT RISK LINE ALMOST
   TO THE OH-PA STATE-LINE.

   ...NRN AND CNTRL HIGH PLAINS...
   SOUTHWEST FLOW IS IN PLACE ACROSS THE NRN AND CNTRL PLAINS WITH A
   SHORTWAVE TROUGH APPROACHING THE REGION FROM THE SOUTHWEST. AT THE
   SFC...A MOIST AXIS EXTENDS FROM CNTRL SD NWWD INTO ERN MT ALONG
   WHICH WINDS ARE BACKED TO THE SOUTHEAST AND DEWPOINTS ARE IN THE MID
   TO UPPER 60S F. ALONG THIS CORRIDOR...MLCAPE IS ESTIMATED AT 2500 TO
   3500 J/KG AND REGIONAL WSR-88D VWPS SHOW 30 TO 40 KT OF 0-6 KM
   SHEAR. THIS COMBINED WITH MID-LEVEL LAPSE RATES EXCEEDING 8.0 C/KM
   SHOULD BE FAVORABLE FOR SUPERCELLS WITH ISOLATED LARGE HAIL. THE
   GREATEST SUPERCELL THREAT SHOULD EXIST ACROSS NERN MT TO THE
   NORTHWEST OF A POCKET OF STRONG INSTABILITY WHERE A 2 PERCENT
   TORNADO PROBABILITY HAS BEEN ADDED. THE POTENTIAL FOR SUPERCELLS MAY
   ALSO BE ENHANCED ACROSS CNTRL AND NRN NEB WHICH IS ALSO CO-LOCATED
   WITH A POCKET OF STRONG INSTABILITY. THE SEVERE THREAT IN NEB AND
   NWD INTO THE DAKOTAS WILL DEPEND UPON STORM COVERAGE. ALTHOUGH
   SHORT-TERM MODELS DIFFER ON HOW MANY STORMS WILL INITIATE...THE
   WRF-HRRR SUGGESTS THAT STORMS WILL CONGEAL INTO SEVERAL LINE
   SEGMENTS THIS EVENING. ANY LINE OR CLUSTER THAT CAN ORGANIZE SHOULD
   HAVE A WIND DAMAGE THREAT.

   ...SRN AND CNTRL PLAINS...
   A CLUSTER OF STRONG TO SEVERE STORMS IS ONGOING IN SW KS ALONG A
   NARROW AXIS OF STRONG INSTABILITY WITH MLCAPE ESTIMATED IN THE 2500
   TO 3500 J/KG RANGE. THIS CONVECTION IS BEING SUPPORTED BY A
   SHORTWAVE TROUGH OVER THE SRN AND CNTRL HIGH PLAINS EVIDENT ON WATER
   VAPOR IMAGERY. REGIONAL PROFILERS SUGGEST THAT 0-6 KM SHEAR IS
   AROUND 40 KT ACROSS MUCH OF THE SRN AND CNTRL PLAINS WHICH COMBINED
   WITH MID-LEVEL LAPSE RATES AROUND 8.5 C/KM SHOULD BE FAVORABLE FOR
   SUPERCELLS WITH ISOLATED LARGE HAIL. IN ADDITION...TEMP-DEWPOINT
   SPREADS EXCEED 30 DEGREES F ACROSS MUCH THE REGION SUGGESTING THAT
   DOWNDRAFT SPEEDS COULD BE ENHANCED. HOWEVER...STORM COVERAGE REMAINS
   RELATIVELY ISOLATED LARGELY DUE TO WARM AIR AT MID-LEVELS. THIS
   SHOULD KEEP THE SEVERE THREAT CONFINED TO AREAS WHERE THE STRONGEST
   INSTABILITY IS PRESENT.

   ..BROYLES.. 06/25/2013

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