SPC AC 311723

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1223 PM CDT THU OCT 31 2013

   VALID 011200Z - 021200Z

   ...NO SVR TSTM AREAS FORECAST...

   ...SYNOPSIS...
   A HIGHLY AMPLIFIED LONGWAVE PATTERN WILL REMAIN OVER THE CONUS
   THROUGH FRIDAY. A FAST-MOVING SHORTWAVE TROUGH/JET STREAK WILL RACE
   NEWD OVER THE NORTHEAST STATES/NEW ENGLAND AND QUEBEC...WHILE
   ADDITIONAL TROUGH AMPLIFICATION OCCURS OVER MUCH OF THE MIDWEST/MS
   RIVER VALLEY THROUGH FRIDAY NIGHT. THE PRIMARY CONVECTIVE POTENTIAL
   WILL EXIST EAST OF THE APPALACHIANS...FROM THE SOUTHEAST STATES
   THROUGH THE MID ATLANTIC REGION TO THE NORTHEAST STATES...WITHIN AN
   UNSEASONABLY MOIST AIR MASS AHEAD OF AN EWD-MOVING COLD FRONT.

   ...CENTRAL/ERN NY INTO NEW ENGLAND...
   IN ASSOCIATION WITH THE AFOREMENTIONED SHORTWAVE TROUGH AND STRONG
   JET STREAK /90-100 KT AT 500 MB/...CONFIDENCE REMAINS LIMITED IN THE
   LIKELIHOOD FOR LIGHTNING-PRODUCING CONVECTION FRIDAY NEAR/AHEAD OF
   THE ADVANCING COLD FRONT. HOWEVER...ESPECIALLY GIVEN STRONG FORCING
   FOR ASCENT AND A RELATIVELY MOIST AIR MASS...CONVECTIVE UPDRAFTS
   ROOTED IN VERY WEAK NEAR-SURFACE BUOYANCY MAY ATTAIN SUFFICIENT
   DEPTHS TO PRODUCE LIGHTNING. GIVEN THE STRONG MAGNITUDE OF THE
   LOW-MID TROPOSPHERIC WINDS...ACCENTUATED BY 50-75 KT WINDS BETWEEN
   1-2 KM...CONVECTIVELY AIDED WIND DAMAGE POTENTIAL COULD EXIST DURING
   THE DAY. SUCH A WIND DAMAGE RISK COULD OCCUR IN ASSOCIATION WITH A
   FAST-MOVING/LOW-TOPPED CONVECTIVE LINE AS IT POTENTIALLY RACES NEWD.

   ...SOUTHEAST TO MID ATLANTIC STATES...
   SURFACE WINDS SHOULD VEER TO SWLY ACROSS THE WARM SECTOR FRIDAY
   MORNING...INITIALLY DECREASING LOW LEVEL CONVERGENCE ALONG THE COLD
   FRONT INTO THE EARLY AFTERNOON. WEAK LAPSE RATES AND WEAK
   INSTABILITY ARE EXPECTED TO LIMIT THE SEVERE WEATHER THREAT INTO
   EARLY TO MID FRIDAY AFTERNOON...BUT THE STRENGTH OF SWLY 850 MB
   WINDS /40-50 KT/ COULD REACH THE SURFACE IN STRONGER LOW-TOPPED
   CONVECTION.

   THE 12Z NAM /AND ALSO INDICATED SOMEWHAT BY THE 12Z GFS/00Z ECMWF/
   SUGGESTS SURFACE WINDS SHOULD BACK TO A MORE SLY TRAJECTORY FRIDAY
   AFTERNOON INTO THE EVENING ACROSS SERN GA AND THE ERN CAROLINAS.
   THIS WIND SHIFT WOULD BE IN RESPONSE TO 1/ SURFACE PRESSURE FALLS
   ATTENDANT TO LEE TROUGHING FROM SRN GA TO THE MID ATLANTIC
   REGION...AND 2/ THE POTENTIAL FOR SURFACE LOW DEVELOPMENT ALONG THE
   FRONT IN VA AND SRN GA. SLY WINDS SHOULD SUSTAIN HIGH MOISTURE
   CONTENT AIR /SURFACE DEW POINTS IN THE UPPER 60S TO NEAR 70 -
   ESPECIALLY OVER ERN GA AND THE ERN CAROLINAS/...AND INCREASE LOW
   LEVEL CONVERGENCE ALONG THE COLD FRONT ADVANCING EWD THROUGH THE
   REMAINDER OF THE MID ATLANTIC AND SERN STATES FRIDAY EVENING.
   ALTHOUGH LAPSE RATES WILL BE WEAK...THE DEGREE OF MOISTURE - DESPITE
   TIME OF DAY - COULD ENHANCE AVAILABLE INSTABILITY /MUCAPE 500-1000 J
   PER KG/ ALONG COASTAL AREAS FROM GA TO ERN NC AND FAR SERN VA FRIDAY
   EVENING.  EFFECTIVE BULK SHEAR WILL BE MORE THAN SUFFICIENT FOR
   ORGANIZED STORMS...WHILE BACKED SURFACE WINDS ENHANCE LOW LEVEL
   HODOGRAPH CURVATURE TO WARRANT AT LEAST A NON-ZERO TORNADO THREAT. 
   GIVEN THE LACK OF MODEL AGREEMENT WITH THE DEGREE OF INSTABILITY AND
   LOW LEVEL CONVERGENCE ALONG THE FRONT...CONFIDENCE IN OVERALL STORM
   COVERAGE TO SUPPORT A SLIGHT RISK ISSUANCE IS NOT GREAT ENOUGH AT
   THIS TIME.  OTHERWISE...A FEW STRONG TO SEVERE STORMS COULD BE
   POSSIBLE FRIDAY EVENING INVOF COASTAL AREAS OF SC/NC TO FAR SERN VA.

   ..PETERS.. 10/31/2013

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