Sep 6, 2014 1300 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   0725 AM CDT SAT SEP 06 2014

   VALID 061300Z - 071200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE NORTHEAST
   U.S. AND NEW ENGLAND...

   ...SUMMARY...
   WIDELY SCATTERED SEVERE STORMS WITH A PRIMARY RISK OF DAMAGING WINDS
   ARE EXPECTED ACROSS NEW ENGLAND AND PARTS OF THE NORTHEAST THIS
   AFTERNOON AND EVENING. MORE ISOLATED STRONG TO SEVERE STORMS ARE
   POSSIBLE FARTHER SOUTH ACROSS THE CENTRAL APPALACHIANS REGION.

   ...SYNOPSIS...
   WITHIN A BROADLY CYCLONIC UPPER-LEVEL FLOW PATTERN FROM HUDSON BAY
   SOUTHWARD ACROSS THE GREAT LAKES AND NORTHEAST STATES...A SHORTWAVE
   TROUGH WILL MOVE EASTWARD FROM NRN ONTARIO INTO QUEBEC THIS FORECAST
   PERIOD.  AN UPSTREAM SHORTWAVE TROUGH...NOW MOVING SEWD THROUGH NRN
   MANITOBA PER MOISTURE-CHANNEL IMAGERY...SHOULD REACH JAMES BAY INTO
   QUEBEC LATE TONIGHT/EARLY SUNDAY...REINFORCING THE AFOREMENTIONED
   CYCLONIC FLOW REGIME. AT THE SURFACE...11Z ANALYSIS SHOWED A COLD
   FRONT EXTENDING SWWD FROM THE SAINT LAWRENCE RIVER VALLEY THROUGH
   LAKES ONTARIO AND ERIE INTO NRN OHIO TO SRN INDIANA.  THIS FRONT
   WILL ADVANCE EAST/SOUTHEAST TODAY...AND SHOULD EXTEND FROM DOWNEAST
   MAINE THROUGH SERN NY...SERN PA TO THE SRN APPALACHIANS BY 07/00Z. 
   IN ADDITION TO THIS FRONT BEING A FOCUS FOR AFTERNOON AND EARLY
   EVENING THUNDERSTORMS...TRENDS IN MOSAIC RADAR IMAGERY INDICATED AN
   OUTFLOW BOUNDARY LEFT OVER FROM FRIDAY EVENING/OVERNIGHT CONVECTION
   EXTENDED FROM NRN KY THROUGH NRN WV...SOUTH-CENTRAL TO NERN PA TO
   NRN VT.

   ...NEW ENGLAND/NORTHEAST U.S. TO THE CENTRAL APPALACHIANS... 
   EARLY MORNING VISIBLE SATELLITE IMAGERY SUGGESTS THE GREATEST
   SURFACE HEATING SHOULD OCCUR EAST AND SOUTH OF THE LATTER CONVECTIVE
   BOUNDARY DESCRIBED IN THE SYNOPSIS...WHILE BREAKS IN THE CLOUDS
   BETWEEN THE COLD FRONT AND OUTFLOW BOUNDARY SHOULD ALLOW FOR
   DESTABILIZATION AS WELL.  ALTHOUGH STRONGEST 500-MB HEIGHT FALLS
   /60+ METERS/ ARE EXPECTED TO REMAIN PRIMARILY NORTH OF THE
   INTERNATIONAL BORDER INTO NRN MAINE...WEAK HEIGHT FALLS ACROSS THE
   SLIGHT RISK AREA AND LOW-LEVEL CONVERGENCE IN VICINITY OF THE
   SURFACE BOUNDARIES SHOULD BE SUFFICIENT FOR NEW TSTM DEVELOPMENT.

   DESPITE WEAK MIDLEVEL LAPSE RATES PRESENT OVER THE NORTHEAST
   STATES...SURFACE HEATING WITHIN A RATHER MOIST ENVIRONMENT /PW
   VALUES OF 1.6-1.9+ INCHES PER 12Z SOUNDINGS AND SURFACE DEW POINTS
   IN THE UPPER 60S TO AROUND 70 F/ WILL RESULT IN MODERATE
   INSTABILITY.  STRONGEST MID-UPPER LEVEL WINDS ARE EXPECTED TO REMAIN
   NORTH OF THE COLD FRONT...BUT 30-40 KT SWLY 700-500-MB FLOW SHOULD
   SUPPORT STORMS THAT ORGANIZE IN CLUSTERS AND/OR LINE
   SEGMENTS...POSING A RISK FOR DAMAGING WINDS DURING THE AFTERNOON AND
   EARLY EVENING HOURS. EFFECTIVE BULK SHEAR OF 35-40 KT...AND 0-1 KM
   SRH MAXIMIZED IN PROXIMITY TO STRONGER LOW-LEVEL WIND FIELDS ACROSS
   NRN PORTIONS OF THE SLIGHT RISK /PRIMARILY NH AND MAINE/ WILL
   SUPPORT SUPERCELL STRUCTURES...AND A TORNADO THREAT CANNOT BE RULED
   OUT. 

   MEANWHILE...FARTHER SOUTH INTO THE CENTRAL APPALACHIANS...WEAKER
   WIND FIELDS SHOULD RESULT IN A MORE ISOLATED SEVERE WIND THREAT.

   ..PETERS/JIRAK.. 09/06/2014