000
WTNT43 KNHC 272055
TCDAT3
 
HURRICANE SANDY DISCUSSION NUMBER  22
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182012
500 PM EDT SAT OCT 27 2012
 
FIRST A NOTE ON THE NWS WARNING STRATEGY FOR SANDY.  IN ORDER TO
AVOID THE RISK OF A HIGHLY DISRUPTIVE CHANGE FROM TROPICAL TO
NON-TROPICAL WARNINGS WHEN SANDY BECOMES POST-TROPICAL...THE WIND
HAZARD NORTH OF THE TROPICAL STORM WARNING AREA WILL CONTINUE TO BE
CONVEYED THROUGH HIGH WIND WATCHES AND WARNINGS WARNINGS ISSUED BY
LOCAL NATIONAL WEATHER SERVICE OFFICES.  
 
SATELLITE IMAGERY SHOWS THAT DRY MID-LEVEL AIR HAS WRAPPED AROUND
THE WESTERN AND SOUTHWESTERN PORTIONS OF THE CIRCULATION...WHICH MAY
HAVE CAUSED THE RECENT WEAKENING OF THE INNER-CORE CONVECTION.  THE
AIR FORCE AIRCRAFT MADE ITS FINAL PASS THROUGH SANDY AROUND 1800
UTC AND REPORTED A MINIMUM PRESSURE OF AROUND 961 MB.  WIND DATA
FROM THE AIRCRAFT AND A RECENT DROPSONDE FROM THE NOAA G-IV AIRCRAFT
CONDUCTING A SURVEILLANCE MISSION AROUND SANDY SUPPORT MAINTAINING
THE INITIAL INTENSITY OF 65 KT.
 
THERE HAS BEEN NO CHANGE TO THE TRACK OR INTENSITY FORECAST
REASONING. SANDY IS LIKELY TO REMAIN AT OR NEAR HURRICANE STRENGTH
DURING THE NEXT DAY OR SO. AFTER THAT TIME...THE CYCLONE WILL
INTERACT WITH A STRONG SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT
MOVING INTO THE EASTERN UNITED STATES. AS THIS OCCURS...THE GLOBAL
MODELS INDICATE THAT THE CYCLONE WILL STRENGTHEN DUE TO BAROCLINIC
PROCESSES...AND THE OFFICIAL FORECAST CALLS FOR SOME INCREASE IN
INTENSITY IN A COUPLE OF DAYS. BY 48 HOURS...THE GFS AND ECMWF
MODELS SHOW COLDER AIR WRAPPING AROUND THE SOUTH PORTION OF THE
CIRCULATION AND SANDY IS LIKELY TO HAVE COMPLETED ITS
TRANSFORMATION TO A VIGOROUS EXTRATROPICAL CYCLONE AT THAT TIME.
AFTER LANDFALL...THE CYCLONE IS FORECAST TO STEADILY WEAKEN.
 
THE GFS AND ECMWF MODELS ARE IN BETTER AGREEMENT THIS AFTERNOON...
WITH THE ECMWF A LITTLE NORTH OF ITS PREVIOUS TRACK. SANDY IS
FORECAST TO MOVE NORTHEASTWARD DURING THE NEXT 24 HOURS...THEN TURN
NORTHWARD AHEAD OF THE APPROACHING MID-LATITUDE TROUGH. THE CYCLONE
SHOULD TURN NORTHWESTWARD...THEN WESTWARD AS IT ROTATES AROUND THE
EASTERN SIDE OF THE DEEPENING TROUGH. ONCE AGAIN...DRAWING A
STRAIGHT LINE BETWEEN THE 48- AND 72-HOUR FORECAST POINTS DOES NOT
QUITE DEPICT HOW CLOSE THE CENTER IS EXPECTED TO COME TO LONG
ISLAND.  HAVING SAID THAT...IT IS STILL TOO SOON TO FOCUS ON THE
EXACT TRACK...BOTH BECAUSE OF FORECAST UNCERTAINTY AND BECAUSE THE
IMPACTS ARE GOING TO COVER SUCH A LARGE AREA AWAY FROM THE CENTER.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  27/2100Z 30.2N  75.2W   65 KT  75 MPH
 12H  28/0600Z 31.5N  73.8W   65 KT  75 MPH
 24H  28/1800Z 33.4N  72.1W   65 KT  75 MPH
 36H  29/0600Z 35.4N  71.1W   65 KT  75 MPH
 48H  29/1800Z 37.9N  72.0W   70 KT  80 MPH...POST-TROP/EXTRATROP
 72H  30/1800Z 40.0N  77.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  31/1800Z 42.5N  76.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  01/1800Z 45.5N  74.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BROWN