Tropical Storm SANDY

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TROPICAL STORM SANDY DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182012
1100 PM EDT TUE OCT 23 2012

REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT SHOW
THAT SANDY IS STRENGTHENING.  THE AIRCRAFT REPORTED 850-MB
FLIGHT-LEVEL WINDS OF 65 KT AND SFMR SURFACE WIND ESTIMATES NEAR 50
KT.  THE MINIMUM CENTRAL PRESSURE WAS 989 MB.  BASED ON THESE
DATA...THE INITIAL INTENSITY IS RAISED TO 50 KT.  THE AIRCRAFT ALSO
REPORTED THAT A RAGGED EYE WAS FORMING.

SANDY IS NOW MOVING FASTER WITH AN INITIAL MOTION OF 015/9.  THE
FORECAST SCENARIO AND THE FORECAST TRACK ARE BASICALLY UNCHANGED
SINCE THE PREVIOUS ADVISORY.  SANDY SHOULD MOVE GENERALLY NORTHWARD
FOR THE NEXT 48 HR AS THE CYCLONE INTERACTS OR MERGES WITH AN
MID/UPPER-LEVEL TROUGH TO ITS NORTHWEST AND A MID-LEVEL RIDGE TO
THE NORTH OF THE CYCLONE WEAKENS.  AFTER 72 HR...SOUTHWESTERLY
MID/UPPER-LEVEL FLOW ASSOCIATED WITH A SECOND TROUGH OVER THE
EASTERN UNITED STATES IS EXPECTED TO TURN THE CYCLONE
NORTHEASTWARD.  THE TRACK FORECAST IS IN GOOD AGREEMENT WITH THIS
SCENARIO...WITH A TIGHT CLUSTERING OF THE GUIDANCE THROUGH 72 HR
AND SOME SPREAD THEREAFTER.  THE NEW FORECAST TRACK LIES NEAR THE
CENTER OF THE GUIDANCE ENVELOPE...BETWEEN THE PREVIOUS FORECAST AND
THE CONSENSUS MODELS.

OVER THE CARIBBEAN...SANDY SHOULD CONTINUE TO INTENSIFY IN AN
ENVIRONMENT OF LIGHT/MODERATE VERTICAL WIND SHEAR.  THE INTENSITY
FORECAST FOLLOWS THE PREVIOUS FORECAST IN MAKING SANDY A HURRICANE
BEFORE THE CENTER REACHES JAMAICA AND CUBA.  THE INTENSITY FORECAST
BECOMES MUCH MORE COMPLEX AFTER THE CYCLONE EMERGES NORTH OF CUBA. 
WHILE ALL OF THE DYNAMICAL GUIDANCE SHOW STRONG SHEAR OVER
SANDY...THEY ALL ALSO SHOW A SIGNIFICANT FALL IN THE CENTRAL
PRESSURE AND AN INCREASE IN THE SIZE OF THE WIND FIELD.  THIS
APPEARS TO BE DUE TO BARCLINIC ENERGY FROM INTERACTION WITH THE
MID/UPPER-LEVEL TROUGHS...AND IT IS LIKELY THAT SANDY WILL LOSE
SOME OF ITS TROPICAL CHARACTERISTICS IN THE PROCESS.  THAT BEING
SAID...NONE OF THE GUIDANCE SHOWS THE CYCLONE ACTUALLY BECOMING
EXTRATROPICAL DURING THE FORECAST PERIOD.  THE NEW INTENSITY
FORECAST WILL FOLLOW THE PREVIOUS FORECAST IN SHOWING A 60-KT
INTENSITY AFTER 36 HR AND THE CYCLONE BECOMING POST-TROPICAL BY 120
HR.  HOWEVER...THIS IS A LOW CONFIDENCE FORECAST FOR BOTH THE
INTENSITY AND THE STRUCTURE OF THE CYCLONE.
 
THE FORECAST TRACK AND EXPANDING WIND RADII SUGGEST THAT A TROPICAL
STORM WATCH COULD BE REQUIRED FOR PORTIONS OF SOUTHEASTERN FLORIDA
AND THE KEYS EARLY WEDNESDAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0300Z 15.2N  77.2W   50 KT  60 MPH
 12H  24/1200Z 16.7N  77.0W   60 KT  70 MPH
 24H  25/0000Z 19.0N  76.7W   70 KT  80 MPH
 36H  25/1200Z 21.7N  76.7W   60 KT  70 MPH
 48H  26/0000Z 24.3N  76.8W   60 KT  70 MPH
 72H  27/0000Z 27.0N  76.5W   60 KT  70 MPH
 96H  28/0000Z 30.5N  72.5W   60 KT  70 MPH
120H  29/0000Z 33.0N  68.0W   60 KT  70 MPH...POST-TROPICAL
 
$$
FORECASTER BEVEN
 
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