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Hurricane SANDY


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HURRICANE SANDY DISCUSSION NUMBER  30...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182012
500 PM EDT MON OCT 29 2012
 
THE CONVECTIVE STRUCTURE OF SANDY HAS DETERIORATED TODAY...EVEN AS
THE CENTRAL PRESSURE HAS CONTINUED TO SLOWLY FALL...SUGGESTING THAT
THE CONVECTION IS NO LONGER DRIVING THE BUS.  THE INTENSIFICATION
OBSERVED THIS MORNING WAS ASSOCIATED WITH STRONG WINDS OCCURRING TO
THE SOUTHWEST OF THE CENTER...OUTSIDE OF THE CENTRAL CORE...AND WAS
ALMOST CERTAINLY DUE TO BAROCLINIC FORCING.  IN ADDITION...AIRCRAFT
DATA INDICATE THAT THERE ARE STRONG TEMPERATURE CONTRASTS VERY NEAR
A MODEST RESIDUAL WARM CORE.  WATER VAPOR IMAGERY INDICATES THAT
SANDY IS BECOMING ABSORBED WITHIN A LARGE MID-LATITUDE CYCLONIC
CIRCULATION.  ALL OF THESE CONSIDERATIONS LEAD US TO CONCLUDE THAT
THE MOST APPROPRIATE CLASSIFICATION AT ADVISORY TIME IS
EXTRATROPICAL.  HOWEVER...FOR CONTINUITY OF SERVICE NHC WILL
CONTINUE TO ISSUE ADVISORIES THROUGH LANDFALL.  A POST-STORM
ANALYSIS WILL RE-EXAMINE THE TIMING OF EXTRATROPICAL TRANSITION.  

WE ANTICIPATES THAT THE LAST NHC ADVISORY ON SANDY WILL BE ISSUED AT
11 PM EDT TONIGHT. SINCE ALL COASTAL TROPICAL CYCLONE WARNINGS HAVE
BEEN DISCONTINUED...THERE WILL BE NO INTERMEDIATE PUBLIC ADVISORIES
ISSUED BETWEEN NOW AND THE 11 PM NHC ADVISORY.  TO PROVIDE A
CONTINUOUS FLOW OF INFORMATION...NHC WILL ISSUE TROPICAL CYCLONE
UPDATES AT 7 PM AND 9 PM EDT...AND AT THE TIME OF LANDFALL.  THESE
UPDATES ARE ISSUED UNDER WMO HEADER WTNT63...AND AWIPS HEADER
TCUAT3...AND WILL ALSO BE AVAILABLE ON THE NHC WEBSITE.  BEGINNING
AT 5 AM EDT TUESDAY...PUBLIC ADVISORIES WILL BE ISSUED BY THE
HYDROMETEOROLOGICAL PREDICTION CENTER...HPC...UNDER THE SAME WMO
AND AWIPS HEADERS AS THE NHC PUBLIC ADVISORIES...WHICH WILL ALSO BE
AVAILABLE VIA THE NHC WEBSITE.

THERE HAS BEEN NO SIGNIFICANT CHANGE TO THE POST-LANDFALL TRACK OR
INTENSITY FORECAST.  DESPITE THE RAPID FORWARD MOTION TODAY...SANDY
IS EXPECTED TO STALL INLAND TOMORROW.  THIS...COUPLED WITH THE VERY
LARGE SIZE OF THE SYSTEM...WILL MEAN THAT CONDITIONS WILL BE SLOW
TO IMPROVE IN THE AFFECTED AREAS.  STRONG WINDS WILL PERSIST ALONG
THE COAST AND SPREAD FARTHER INLAND THROUGH AT LEAST TUESDAY.  OF
PARTICULAR CONCERN ARE THE UPPER FLOORS OF HIGH-RISE BUILDINGS...AS
RECONNAISSANCE DATA INDICATE THAT WINDS JUST A FEW HUNDRED FEET IN
ALTITUDE ARE VERY MUCH STRONGER THAN THOSE NEAR THE SURFACE.  EVEN
AS SANDY WEAKENS...HEAVY RAINS WILL PERSIST OVER A LARGE
AREA...POSING A VERY SIGNIFICANT INLAND FLOOD RISK.

TO AVOID A HIGHLY DISRUPTIVE CHANGE FROM TROPICAL TO NON-TROPICAL
WARNINGS AS SANDY BECOMES POST-TROPICAL...THE WIND AND OTHER
HAZARDS WILL CONTINUE TO BE CONVEYED THROUGH HIGH WIND WARNINGS
ISSUED BY LOCAL NATIONAL WEATHER SERVICE OFFICES. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/2100Z 38.8N  74.4W   80 KT  90 MPH
 12H  30/0600Z 39.8N  76.6W   65 KT  75 MPH...POST-TROP/EXTRATROP
 24H  30/1800Z 40.4N  78.3W   50 KT  60 MPH...POST-TROP/EXTRATROP
 36H  31/0600Z 41.3N  78.2W   40 KT  45 MPH...POST-TROP/EXTRATROP
 48H  31/1800Z 42.8N  77.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  01/1800Z 45.1N  75.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 96H  02/1800Z 46.3N  72.2W   25 KT  30 MPH...POST-TROP/EXTRATROP
120H  03/1800Z 47.5N  65.5W   20 KT  25 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER KNABB/FRANKLIN
 
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