000
WTNT43 KNHC 261459
TCDAT3
 
HURRICANE SANDY DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182012
1100 AM EDT FRI OCT 26 2012
 
STRONG SOUTH-SOUTHWESTERLY SHEAR AND THE INTRUSION OF DRY AIR
CONTINUES TO AFFECT THE HURRICANE...AS VISIBLE SATELLITE IMAGES
SHOW THAT THE LOW-LEVEL CENTER OF SANDY IS EXPOSED TO THE SOUTH OF
THE MAIN MASS OF CONVECTION.  USING A BLEND OF FLIGHT-LEVEL AND
SFMR WINDS FROM THE HURRICANE HUNTER AIRCRAFT YIELDS A CURRENT
INTENSITY ESTIMATE OF 70 KT.  DYNAMICAL MODELS SHOW AN ADDITIONAL
INCREASE IN SHEAR OVER THE NEXT 24 HOURS...WHICH SHOULD CAUSE AT
LEAST SLIGHT WEAKENING.  LATER IN THE FORECAST PERIOD...GLOBAL
MODELS SHOW SOME RE-INTENSIFICATION OF THE CYCLONE...WHICH IS VERY
LIKELY DUE TO BAROCLINIC INFLUENCES.  BY 72 HOURS...THE MODELS SHOW
SIGNIFICANT COLD AIR ADVECTION OVER THE SOUTHWEST PORTION OF THE
CIRCULATION...WHICH SHOULD HASTEN THE EXTRATROPICAL TRANSITION
PROCESS.  THE OFFICIAL FORECAST SHOWS THE SYSTEM AS POST-TROPICAL
AT 96 HOURS...THOUGH THERE IS SOME UNCERTAINTY AS TO THE TIMING OF
THE TRANSITION.  REGARDLESS...WHETHER SANDY IS OFFICIALLY TROPICAL
OR POST-TROPICAL AT LANDFALL WILL HAVE LITTLE BEARING ON THE
IMPACTS.
 
LATEST FIXES FROM HURRICANE HUNTER AIRCRAFT SHOW A VERY SLOW MOTION
WITH THE CENTER APPEARING TO HAVE TURNED NORTHWARD.  THE CURRENT
MOTION ESTIMATE IS 360/5.  SANDY IS EXPECTED TO ESCAPE THE
INFLUENCE OF A MID- TO UPPER-LEVEL TROUGH AND TO BEGIN TO MOVE
NORTH-NORTHEASTWARD TO NORTHEASTWARD WITH AN INCREASE IN FORWARD
SPEED OVER THE NEXT FEW DAYS.  A SHORTWAVE TROUGH NEAR THE PACIFIC
NORTHWEST COAST IS FORECAST TO MOVE EAST-SOUTHEASTWARD AND DIG AS
IT APPROACHES THE EASTERN U.S. COAST BY 72 HOURS.  THE FLOW ON THE
NORTHEAST SIDE OF THIS SHORTWAVE SHOULD CAUSE SANDY TO TURN TOWARD
THE NORTH AND NORTHWEST TOWARD THE COAST.  THE OFFICIAL TRACK
FORECAST IS VERY SIMILAR TO THE PREVIOUS ONE AND ALSO VERY CLOSE TO
THE LATEST DYNAMICAL MODEL CONSENSUS.  USERS ARE REMINDED TO NOT
FOCUS ON THE DETAILS OF THE TRACK FORECAST LATE IN THE PERIOD...AS
SANDY IS EXPECTED TO BRING IMPACTS TO A LARGE PART OF THE U.S. EAST
COAST INTO EARLY NEXT WEEK. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  26/1500Z 26.7N  76.9W   70 KT  80 MPH
 12H  27/0000Z 27.6N  77.4W   70 KT  80 MPH
 24H  27/1200Z 28.9N  76.8W   65 KT  75 MPH
 36H  28/0000Z 30.5N  75.5W   65 KT  75 MPH
 48H  28/1200Z 32.2N  73.7W   70 KT  80 MPH
 72H  29/1200Z 36.0N  72.5W   70 KT  80 MPH
 96H  30/1200Z 39.0N  75.5W   65 KT  75 MPH...POST-TROPICAL
120H  31/1200Z 40.5N  78.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER PASCH