000
WTNT43 KNHC 290856
TCDAT3
 
HURRICANE SANDY DISCUSSION NUMBER  28
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182012
500 AM EDT MON OCT 29 2012
 
SANDY CONTINUES TO MAINTAIN AN AREA OF DEEP CONVECTION NEAR THE
CENTER...WITH AN EYE OCCASIONALLY VISIBLE ON SATELLITE IMAGERY. 
ALTHOUGH THE SATELLITE PRESENTATION OF THE SYSTEM IS NOT VERY
IMPRESSIVE...SFMR MEASUREMENTS...FLIGHT-LEVEL WINDS...AND DROPSONDE
DATA FROM THE AIR FORCE HURRICANE HUNTERS INDICATE THAT THE WINDS
HAVE INCREASED TO NEAR 75 KT.  SINCE THE HURRICANE WILL TRAVERSE
THE GULF STREAM THIS MORNING...AND THE SHEAR IS NOT TOO STRONG AT
THIS TIME...SOME MORE STRENGTHENING AS A TROPICAL CYCLONE IS
POSSIBLE IN THE NEXT FEW HOURS.  HOWEVER...THE MAIN MECHANISM
FOR INTENSIFICATION LATER TODAY SHOULD BE BAROCLINIC FORCING.  THE
OFFICIAL WIND SPEED FORECAST IS CLOSE TO THE LATEST GFS PREDICTION
AS THAT MODEL SHOULD BE ABLE TO HANDLE THE EVOLUTION OF THIS TYPE
OF SYSTEM FAIRLY WELL.
 
SURFACE DATA INDICATE THAT A WELL-MARKED WARM AND COLD FRONT LIE NOT
FAR TO THE NORTH AND WEST OF THE CENTER OF SANDY.  AS THE
CIRCULATION INTERACTS WITH THESE FRONTS...THE CYCLONE SHOULD BECOME
EXTRATROPICAL LATER TODAY.  EXTRATROPICAL TRANSITION IS EXPECTED TO
BE COMPLETE BEFORE THE CENTER CROSSES THE COAST.  HOWEVER...THIS
TRANSFORMATION WILL NOT DIMINISH THE OVERALL IMPACTS FROM WINDS TO
HURRICANE STRENGTH...LIFE-THREATENING STORM SURGE...AND FLOODING
RAINS ASSOCIATED WITH THIS DANGEROUS WEATHER SYSTEM.  BASED ON THE
GLOBAL MODELS...THE CYCLONE SHOULD WEAKEN FAIRLY RAPIDLY AFTER
LANDFALL.
 
CENTER FIXES INDICATE THAT SANDY IS NOW MOVING NORTHWARD OR ABOUT
360/13...AS IT BEGINS TO ROTATE AROUND A MID- TO UPPER-LEVEL
CYCLONE OVER THE SOUTHEASTERN UNITED STATES.  AS IT MOVES BETWEEN
THE CYCLONE AND A HIGHLY ANOMALOUS MID-TROPOSPHERIC RIDGE NEAR
ATLANTIC CANADA...SANDY SHOULD TURN NORTHWESTWARD AND
WEST-NORTHWESTWARD WITH SOME FURTHER INCREASE IN FORWARD SPEED.
THIS TRACK SHOULD RESULT IN THE CENTER MAKING LANDFALL IN THE
MID-ATLANTIC STATES THIS EVENING OR TONIGHT.  AFTER LANDFALL...THE
DYNAMICAL GUIDANCE SHOWS A SIGNIFICANT SLOWING OF FORWARD SPEED AS
THE SYSTEM MERGES WITH THE MID- TO UPPER-LEVEL CYCLONE.  THE
OFFICIAL TRACK FORECAST FOR THIS PACKAGE IS A BIT FASTER THAN THE
PREVIOUS ONE...AND CLOSE TO THE GFS AND ECMWF SOLUTIONS.
 
INTERESTS ARE REMINDED NOT TO FOCUS ON THE CENTER OR THE EXACT
FORECAST TRACK OF THIS SYSTEM...SINCE STRONG WINDS COVER AN AREA
SEVERAL HUNDRED MILES ACROSS...AND THE HIGHEST WINDS WILL NOT
NECESSARILY BE NEAR THE CENTER.
 
AS NOTED IN PREVIOUS ADVISORIES...TO AVOID 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 ISSUED BY LOCAL NATIONAL WEATHER SERVICE OFFICES.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0900Z 35.9N  70.5W   75 KT  85 MPH
 12H  29/1800Z 37.8N  72.0W   80 KT  90 MPH
 24H  30/0600Z 39.5N  75.5W   65 KT  75 MPH...POST-TROP/EXTRATROP
 36H  30/1800Z 40.0N  77.3W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  31/0600Z 40.5N  77.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  01/0600Z 44.0N  76.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 96H  02/0600Z 45.5N  74.0W   25 KT  30 MPH...POST-TROP/EXTRATROP
120H  03/0600Z 46.5N  70.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER PASCH/CANGIALOSI