SPC AC 301609

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1109 AM CDT TUE JUN 30 2015

   VALID 301630Z - 011200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE OH
   VALLEY...THE MID ATLANTIC REGION...AND THE SOUTHEAST STATES...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE NORTHERN
   HIGH PLAINS...

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF AZ...

   ...THERE IS A MRGL RISK OF SVR TSTMS EXTENDING FROM THE NORTHERN
   PLAINS INTO MUCH OF THE MS/OH/TN VALLEYS AND EAST COAST...

   ...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF AZ...

   ...SUMMARY...
   SCATTERED SEVERE STORMS WITH DAMAGING WINDS AND SOME HAIL ARE MOST
   PROBABLE ACROSS THE OHIO VALLEY TO THE DEEP SOUTH AND THE
   MID-ATLANTIC STATES THIS AFTERNOON INTO EARLY EVENING.  AFTERNOON
   THUNDERSTORMS WILL OFFER A DAMAGING-GUST THREAT OVER PARTS OF
   CENTRAL AND SOUTHERN ARIZONA.  LARGE HAIL AND SEVERE WINDS ARE
   EXPECTED WITH A FEW SEVERE STORMS OVER THE NORTHERN GREAT PLAINS AND
   BLACK HILLS IN THE LATE AFTERNOON AND EVENING.

   ...SYNOPSIS...
   A COMPLEX CONVECTIVE DAY IS FORECAST ACROSS THE UNITED STATES...WITH
   SEVERAL AREAS UNDER RISK OF STRONG/SEVERE STORMS.  IN GENERAL...FEW
   CHANGES HAVE BEEN MADE TO THE ONGOING FORECAST.

   ...OH VALLEY...
   A SHORTWAVE TROUGH OVER IND WILL ROTATE EASTWARD ACROSS PARTS OF
   OH/KY AND INTO WV/PA THIS AFTERNOON.  SCATTERED THUNDERSTORMS HAVE
   BEGUN TO INTENSIFY OVER THIS AREA...WITH SUFFICIENT WINDS ALOFT
   SUPPORTING CONVECTIVE ORGANIZATION AND A RISK OF LOCALLY GUSTY WINDS
   AND HAIL. PLEASE REFER TO MCD 1238 FOR FURTHER SHORT-TERM DETAILS.

   ...MID ATLANTIC REGION...
   SEVERAL WEAK MID/UPPER LEVEL PERTURBATIONS ARE ROTATING ACROSS THE
   CENTRAL APPALACHIANS THIS MORNING...WHICH WILL LIKELY LEAD TO
   SPORADIC CLUSTERS OF THUNDERSTORMS.  WHILE SPECIFIC DETAILS OF THE
   TIMING/LOCATION OF THESE CLUSTERS IS UNCERTAIN...FORECAST SOUNDINGS
   FROM SOUTHEAST NY/EASTERN PA INTO MD/VA SUGGEST A VEERING WIND
   PROFILE WITH HEIGHT AND VERTICAL SHEAR FAVORABLE FOR
   ORGANIZED/SEVERE STORMS.  SOME AFTERNOON HEATING MAY LEAD TO POCKETS
   OF MLCAPE AROUND 1000 J/KG AND THE RISK OF A FEW ROTATING STORMS. 
   DAMAGING WINDS WOULD BE THE MAIN THREAT...ALTHOUGH A TORNADO OR TWO
   ARE ALSO POSSIBLE.

   ...SOUTHEAST...
   A LARGE ONGOING CLUSTER OF THUNDERSTORMS CURRENTLY EXTENDS ACROSS
   CENTRAL MS INTO CENTRAL AL AND NORTHWEST GA.  STRONG HEATING IS
   OCCURRING ALONG THE SOUTHERN FLANK OF THIS CONVECTION...WHERE STEEP
   LOW LEVEL LAPSE RATES AND MODERATE CAPE WILL SOON DEVELOP.  THIS
   CORRIDOR APPEARS MOST FAVORABLE FOR A FEW SEVERE STORMS LATER TODAY
   WITH LOCALLY DAMAGING WINDS.

   ...NORTHERN HIGH PLAINS...
   A STRONG SHORTWAVE TROUGH IS TOPPING THE RIDGE OVER SOUTHERN
   SASK...AND WILL TRACK SOUTHEASTWARD INTO PARTS OF MT/ND/SD THIS
   EVENING.  SEVERAL CAM SOLUTIONS INDICATE SCATTERED THUNDERSTORM
   DEVELOPMENT AHEAD OF THIS SYSTEM ALONG A ZONE FROM EASTERN
   MT/WESTERN ND INTO WESTERN SD.  STRONG WINDS ALOFT WILL PROMOTE
   SUPERCELL STORM STRUCTURES CAPABLE OF LARGE HAIL...DAMAGING
   WINDS...AND PERHAPS ISOLATED TORNADOES.  STORMS MAY PERSIST THROUGH
   MUCH OF THE EVENING AND TRACK INTO SD BEFORE WEAKENING.

   ...AZ...
   WATER VAPOR SUGGESTS A SUBTLE SHORTWAVE TROUGH OVER EASTERN AZ
   ROTATING WESTWARD ACROSS THE REGION.  TIMING OF THIS SYSTEM MAY NOT
   BE OPTIMAL FOR CONVECTION TO FORM OVER THE HIGHER TERRAIN OF EASTERN
   AZ AND TRACK INTO THE LOWER DESERTS...BUT OTHER ENVIRONMENTAL
   PARAMETERS APPEAR FAVORABLE FOR STORM-SCALE INTENSE DOWNBURSTS. 
   THEREFORE HAVE MAINTAINED THE ONGOING SLIGHT RISK.

   ..HART/COHEN.. 06/30/2015

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