SPC AC 031627

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1127 AM CDT THU JUL 03 2014

   VALID 031630Z - 041200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID-ATLANTIC STATES
   INTO WRN/NRN NEW ENGLAND...

   ...THERE IS A SLGT RISK OF SVR TSTMS ALONG THE NC CST...

   ...SUMMARY...
   SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING OVER
   PARTS OF THE MID-ATLANTIC STATES AND NEW ENGLAND...WITH DAMAGING
   WIND GUSTS THE PRIMARY THREAT. FARTHER SOUTH...HURRICANE ARTHUR MAY
   PRODUCE A COUPLE TORNADOES OVER COASTAL AREAS OF NORTH CAROLINA. 
   ISOLATED STRONG TO SEVERE STORMS ALSO MAY OCCUR OVER THE NORTHERN
   ROCKIES AND ADJACENT HIGH PLAINS.

   ...SYNOPTIC SETUP...
   GRT LKS/OH VLY TROUGH WILL PROGRESS SLOWLY E THROUGH FRI AS
   SHORTWAVE IMPULSE NOW OVER OH SHEARS NNE INTO WRN QUE AND UPSTREAM
   DISTURBANCE NOW IN MN CONTINUES SE INTO IND. FARTHER W...UPR LOW
   ALONG THE BC CST SHOULD ELONGATE EWD INTO AB...ENHANCING WSW FLOW
   OVER THE NRN RCKYS...AND DEAMPLIFYING DOWNSTREAM RIDGE OVER THE NRN
   PLNS. ELSEWHERE...NHC FCSTS HRCN ARTHUR TO GRAZE THE NC CST AS IT
   ACCELERATES NNE AND...LATER...NEWD THROUGH EARLY FRI.

   AT LWR LVLS...MORNING ANALYSES SHOW SECONDARY COLD FRONTAL SURGE
   /ASSOCIATED WITH OH UPR IMPULSE/ NOW NEARING THE WRN SLOPES OF THE
   CNTRL APPALACHIANS. THIS BOUNDARY SHOULD CONTINUE E INTO CNTRL
   PORTIONS OF NY/PA...AND INTO WRN MD/VA LATER TODAY...OVERTAKING
   OLDER/WEAKER BOUNDARY STALLED OVER THE REGION. IN THE WEST...LEE
   CYCLONE/TROUGH WILL STRENGTHEN OVER MT AS WLY FLOW INCREASES ALOFT.

   ...MID-ATLANTIC/NEW ENGLAND THIS AFTN/EVE...
   SFC HEATING OF VERY MOIST /PW 1.75-2.00 INCHES/...MODERATELY SHEARED
   ENVIRONMENT SHOULD PROMOTE ANOTHER ROUND OF NUMEROUS DIURNAL STORMS
   ALONG AND AHEAD OF CNTRL/NRN APPALACHIANS COLD FRONT. DEVELOPMENT
   LIKELY ALSO WILL BE FOSTERED BY NNE-MOVING OH UPR IMPULSE. WIND
   PROFILES OVER THE REGION ARE SLIGHTLY STRONGER BUT SOMEWHAT BACKED
   RELATIVE TO YESTERDAY...WITH 35-40 KT SWLY DEEP SHEAR EXPECTED TO
   PERSIST THROUGH THIS EVE FROM WRN/NRN VA NEWD INTO WRN/NRN NEW
   ENGLAND. OVERALL SETUP APPEARS SIMILAR TO YESTERDAY...WITH THE
   GREATEST OVERLAP OF BUOYANCY AND DEEP SHEAR FAVORABLE FOR SUSTAINED
   STORMS/TRANSIENT SUPERCELLS SHIFTED A BIT SWWD INTO CNTRL/ERN PA AND
   SERN NY.  UPSCALE ORGANIZATION OF THE CONVECTION INTO CLUSTERS/BANDS
   APPEARS LIKELY...WITH A RISK FOR DMGG WIND...MARGINALLY SVR
   HAIL...AND PERHAPS A TORNADO.

   ...NC CST TODAY THROUGH EARLY FRI...
   LATEST NHC FCST TRACK FOR HRCN ARTHUR WILL ALLOW QUADRANT OF THE
   CIRCULATION MOST FAVORABLE FOR LOW-LVL MESOCYCLONE DEVELOPMENT TO AT
   LEAST GRAZE THE FAR ERN PARTS OF NC LATER TODAY INTO TNGT. UPDRAFTS
   IN THE INITIAL OUTER CONVECTIVE BANDS NOW AFFECTING THE CAPE
   FEAR/CAPE LOOKOUT AREA APPEAR TO LARGELY BE OUTFLOW-DRIVEN.
   HOWEVER...CELLS WITH A GREATER LOW-LVL MESOCYCLOGENESIS POTENTIAL
   MAY MOVE/DEVELOP NWWD INTO THE AREA A BIT LATER TODAY THROUGH TNGT
   AS ENVELOPE OF MORE SHELTERED HIGH THETA-E AIR MORE DIRECTLY
   ASSOCIATED WITH ARTHUR NEARS THE CST /REF MCD 1260/. GIVEN STRENGTH
   OF LOW-LVL SHEAR...QUALITY OF LOW-LVL MOISTURE...AND THE PROXIMITY
   OF THE GULF STREAM STORM UPDRAFTS...A CONDITIONAL RISK MAY DEVELOP
   FOR TORNADOES AND/OR WATERSPOUTS.

   ...NRN RCKYS/ADJACENT HIGH PLNS THIS AFTN/EVE...
   WEAK HEIGHT FALLS ASSOCIATED WITH FLATTENING OF DOWNSTREAM NRN PLNS
   RIDGE WILL PROVIDE MODEST LARGE SCALE ASCENT ACROSS ID/MT TODAY AS
   LEE TROUGH/LOW-LVL PRESSURE GRADIENT SOMEWHAT STRENGTHEN. ASCENT
   ALSO MAY BE ENHANCED IN NRN MT BY TAIL END OF UPR IMPULSE LIFTING
   NEWD INTO AB. MOISTURE WILL REMAIN RELATIVELY SPARSE...WITH PW
   AROUND 0.75-1.00 IN. BUT COUPLED WITH STRONG DIFFERENTIAL HEATING OF
   ELEVATED TERRAIN AND STEEP LOW TO MID-LVL LAPSE RATES...EXPECT SCTD
   AFTN TSTMS OVER THE REGION. 25-30 KT WLY DEEP SHEAR MAY SUPPORT WEAK
   UPSCALE ORGANIZATION INTO SMALL CLUSTERS/BANDS CAPABLE OF HAIL
   AND...ESPECIALLY...LOCALLY DMGG WIND GIVEN WELL-MIXED SUB CLOUD
   LAYERS.

   FARTHER S...ISOLD TO SCTD DRY TSTMS MAY OCCUR FROM THE NRN
   INTERMOUNTAIN REGION ACROSS THE ERN GRT BASIN TO THE FOUR CORNERS
   AND NRN AZ...WHERE A TRANSITION TO MORE MOIST...SW-U.S. MONSOON-TYPE
   OF CONVECTION IS EXPECTED OVER SRN AZ AND NM.

   ..CORFIDI/SMITH.. 07/03/2014

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