Sep 12, 2013 0600 UTC Day 1 Convective Outlook

DAY 1 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK
   1230 AM CDT THU SEP 12 2013

   VALID 121200Z - 131200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE NORTHEAST...

   ...SYNOPSIS...
   A PAIR OF MID-LEVEL VORTICITY MAXIMA WILL AID IN THE AMPLIFICATION
   OF A LARGER-SCALE TROUGH ACROSS SERN CANADA/NERN CONUS INTO EARLY
   FRI. THE LEAD IMPULSE OVER THE UPPER GREAT LAKES WILL MOVE EWD
   ACROSS ONTARIO/QUEBEC...DAMPENING SOMEWHAT AS THE UPSTREAM IMPULSE
   OVER MANITOBA DIGS SEWD ACROSS THE GREAT LAKES. AT THE
   SURFACE...COLD FRONTS WILL ACCOMPANY EACH VORTICITY MAXIMA WITH THE
   STRONGER SURGE OCCURRING WITH THE LATTER IMPULSE. 

   ...NORTHEAST...
   ISOLATED DAMAGING WIND/SEVERE HAIL AND PERHAPS A TORNADO APPEARS
   MOST PROBABLE ACROSS NRN NEW ENGLAND TODAY GIVEN A 30-40 KT SWLY
   LLJ. ISOLATED DAMAGING WIND SHOULD BE THE PRIMARY THREAT FARTHER TO
   THE S/SW WHERE DEEP-LAYER FLOW IS WEAKER.

   SCATTERED SHOWERS AND ISOLATED STORMS WILL LIKELY BE ONGOING THIS
   MORNING IN ASSOCIATION WITH THE AFOREMENTIONED LEAD SHORTWAVE
   IMPULSE AND FRONTAL ZONE. THIS CONVECTION ALONG WITH EXTENSIVE
   OVERTURNING SINCE WED AFTERNOON SHOULD SERVE TO LIMIT INSTABILITY
   COMPARED TO YESTERDAY. THE TRACK OF THE LEAD IMPULSE WILL RESULT IN
   STRONG DEEP-LAYER SHEAR LARGELY REMAINING CONFINED IN THE WARM
   SECTOR TO NRN NEW ENGLAND. BUT WITH WIDESPREAD MIDDLE 60S TO LOWER
   70S SURFACE DEW POINTS...DIURNAL HEATING /MORE PRONOUNCED WITH SRN
   EXTENT/ SHOULD YIELD WEAK TO MODERATE BUOYANCY WITH MLCAPE
   INCREASING TO 750-1500 J/KG BY EARLY AFTERNOON. THIS SHOULD BE
   CONCOMITANT WITH STORMS INCREASING IN COVERAGE WITH THE POSSIBILITY
   OF ORGANIZED LINE SEGMENTS AND EMBEDDED SUPERCELLS TO THE NE AND
   SEMI-ORGANIZED BROKEN BANDS TO THE SW. 

   ...OH VALLEY...
   A MARGINAL RISK FOR LOCALLY DAMAGING WIND/SEVERE HAIL IS EXPECTED
   THIS AFTERNOON AND EVENING. 

   STRONG SURFACE HEATING IS ANTICIPATED ALONG/AHEAD OF AN INITIAL COLD
   FRONT NEAR THE OH RIVER...YIELDING MODERATE BUOYANCY WITH MLCAPE
   LIKELY REACHING 1000-2000 J/KG S OF THE RIVER. CONVECTION SHOULD
   INITIALLY FORM ALONG THIS BOUNDARY AND DEVELOP SEWD WITHIN MODEST
   NWLY STEERING FLOW. MUCH STRONGER DEEP-LAYER NWLYS WILL ACCOMPANY A
   SECONDARY FRONTAL SURGE IN ASSOCIATION WITH THE SHORTWAVE TROUGH
   DIGGING TOWARDS THE GREAT LAKES. ALTHOUGH LOW-LEVEL MOISTURE MAY BE
   SCANT FOR DEEP CONVECTION...STRONG FORCING FOR ASCENT/SHEAR COULD
   YIELD MARGINAL SEVERE WITH ISOLATED STORMS ALONG THE LATTER COLD
   FRONT.