SPC AC 190712

   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0212 AM CDT FRI JUN 19 2015

   VALID 211200Z - 221200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID MS
   VALLEY AND NRN OH VALLEY...

   ...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL AND
   NRN PLAINS...

   ...SUMMARY...
   STRONG TO SEVERE THUNDERSTORMS MAY OCCUR ON SUNDAY FROM THE MID
   MISSISSIPPI VALLEY EASTWARD ACROSS THE NORTHERN OHIO VALLEY WHERE
   DAMAGING WIND GUSTS AND HAIL WILL BE POSSIBLE. OTHER MARGINALLY
   SEVERE THUNDERSTORMS WITH WIND DAMAGE AND HAIL POTENTIAL MAY OCCUR
   ACROSS PARTS OF THE NORTHEASTERN STATES. MARGINALLY SEVERE STORMS
   WITH HAIL AND STRONG WIND GUSTS WILL ALSO BE POSSIBLE IN PARTS OF
   THE CENTRAL AND NORTHERN PLAINS...LOWER TO MID MISSOURI VALLEY AND
   IN THE CENTRAL APPALACHIAN MOUNTAINS ON SUNDAY.

   ...MID MS AND OH VALLEYS...
   A LONG STRETCH OF WEST TO NORTHWEST MID-LEVEL FLOW IS FORECAST ON
   SUNDAY ACROSS MUCH OF THE NRN CONUS. AN UPPER-LEVEL TROUGH IS
   FORECAST TO MOVE INTO THE NRN PLAINS AS A BELT OF STRONG MID-LEVEL
   FLOW SPREADS EWD ACROSS THE NCNTRL STATES. AT THE SFC...A
   QUASI-STATIONARY FRONT IS FORECAST TO BE IN PLACE FROM THE CNTRL
   PLAINS EWD INTO NRN PARTS OF THE OH VALLEY...ALONG WHICH
   THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE SUNDAY AFTERNOON. DUE TO
   THE MID-LEVEL FLOW WHICH IS FORECAST TO BE PARALLEL TO AN ELONGATED
   EAST TO WEST FETCH OF STRONG INSTABILITY...A DAMAGING WIND EVENT CAN
   NOT BE RULED OUT ACROSS THE MID MS VALLEY AND NRN OH VALLEY SUNDAY
   AFTERNOON. NAM FORECAST SOUNDING FOR 21Z/SUNDAY FROM CNTRL IL EWD
   INTO SRN OH SHOW SFC DEWPOINTS IN THE LOWER 70S F...MLCAPE VALUES OF
   3000 TO 4500 J/KG WITH 30 TO 40 KT OF 0-6 KM SHEAR. THIS WOULD BE
   FAVORABLE FOR SEVERE STORMS ESPECIALLY IF A FORWARD PROPAGATING
   BOWING LINE SEGMENT CAN DEVELOP LATE SUNDAY AFTERNOON. AT THIS
   POINT...THE MAGNITUDE OF THE SEVERE THREAT REMAINS UNCERTAIN AND
   COULD BE DRIVEN BY MESOSCALE FACTORS. THE THREAT OF A SEVERE MCS
   APPEARS GREAT ENOUGH TO WARRANT THE ADDITION OF A SLIGHT RISK AREA
   EXTENDING EAST TO WEST ACROSS THE OH VALLEY STATES.

   ...NORTHEASTERN STATES...
   A SUBTLE UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD INTO THE NERN
   STATES ON SUNDAY AS A COLD FRONT ADVANCES SEWD INTO THE LOWER GREAT
   LAKES REGION. MODERATE INSTABILITY AHEAD OF THE FRONT AND INCREASING
   LOW-LEVEL CONVERGENCE SHOULD RESULT IN THE INITIATION OF
   THUNDERSTORMS ALONG THE BOUNDARY DURING THE AFTERNOON. THIS
   CONVECTION IS FORECAST TO MOVE EWD ACROSS NRN PA...NY AND INTO WRN
   NEW ENGLAND DURING THE LATE AFTERNOON. FORECAST SOUNDINGS IN THE
   HUDSON VALLEY OF ERN NY AT 00Z/MONDAY SHOW SFC DEWPOINTS IN THE
   UPPER 60S F WITH MLCAPE NEAR 1500 J/KG AND 25 TO 30 KT OF 0-6 KM
   SHEAR. THIS MAY BE ENOUGH FOR AN ISOLATED WIND DAMAGE THREAT WITH
   THE STRONGER MULTICELL LINE SEGMENTS.

   ...NRN AND CNTRL PLAINS...
   A SHORTWAVE TROUGH IS FORECAST TO MOVE EWD INTO THE NRN PLAINS ON
   SUNDAY AS A COLD FRONT ADVANCES SEWD ACROSS THE REGION. AHEAD OF THE
   FRONT...MODERATE INSTABILITY SHOULD DEVELOP BY AFTERNOON WITH
   THUNDERSTORMS INITIATING ALONG THE BOUNDARY. ALTHOUGH MODERATE
   DEEP-LAYER SHEAR IS FORECAST ACROSS THE NRN PLAINS WHICH COULD BE
   SUFFICIENT FOR SEVERE STORMS...MODEL SOLUTIONS VARY CONCERNING THE
   TIMING OF THE FRONT AND MAGNITUDE OF INSTABILITY AHEAD OF THE FRONT.
   FOR THIS REASON...WILL KEEP THE THREAT AT MARGINAL ACROSS THE CNTRL
   AND NRN PLAINS SUNDAY AFTERNOON. HAIL AND STRONG GUSTY WINDS SHOULD
   BE THE PRIMARY THREATS WITH THE MORE INTENSE CELLS.

   ..BROYLES.. 06/19/2015

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