Tropical Storm RAFAEL

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TROPICAL STORM RAFAEL DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172012
500 PM AST MON OCT 15 2012
 
THE ORGANIZATION OF RAFAEL HAS CHANGED VERY LITTLE SINCE THIS
MORNING.  MICROWAVE DATA SHOWS THAT THERE IS SIGNIFICANT SOUTHWEST
TO NORTHEAST TILT BETWEEN THE LOW- AND MID-LEVEL CENTERS DUE TO
MODERATE SOUTHWESTERLY SHEAR.  DVORAK SATELLITE ESTIMATES ONCE AGAIN
SUPPORT HURRICANE STRENGTH...BUT GIVEN THE LACK OF IMPROVED
SATELLITE PRESENTATION AND THE EARLIER AIRCRAFT SFMR SURFACE 
WIND MEASUREMENTS...RAFAEL REMAINS A 60-KT TROPICAL STORM.  NOAA AND
U.S. AIR FORCE HURRICANE HUNTER AIRCRAFT ARE EN ROUTE TO THE STORM
AND SHOULD PROVIDE VALUABLE DATA THIS EVENING.

DESPITE THE SHEAR...THE NHC INTENSITY FORECAST STILL CALLS FOR
RAFAEL TO REACH HURRICANE STRENGTH TONIGHT OR TUESDAY.  HOWEVER... 
THE OPPORTUNITY FOR SIGNIFICANT STRENGTHENING APPEARS TO BE
LESSENING AS THE SHEAR IS FORECAST TO INCREASE AND RAFAEL WILL BE
MOVING OVER DECREASING SSTS IN 36 TO 48 HOURS.  THE GLOBAL MODEL
GUIDANCE SUGGESTS THAT RAFAEL WILL BEGIN THE TRANSITION TO
EXTRATROPICAL STATUS WITHIN 48 HOURS...AS IT STARTS TO INTERACT
WITH A LARGE MID-LATITUDE TROUGH AND ASSOCIATED COLD FRONT MOVING
OFF THE U.S. EAST COAST...THE CANADIAN MARITIMES...AND ATLANTIC
CANADA.  THE TRANSITION TO AN EXTRATROPICAL LOW IS EXPECTED TO BE
COMPLETE WITHIN 72 HOURS...IF NOT SOONER. 

IT APPEARS THAT RAFAEL HAS MADE THE ANTICIPATED NORTHWARD TURN.  THE
STORM SHOULD BEGIN TO ACCELERATE NORTHEASTWARD ON TUESDAY AS THE
AFOREMENTIONED TROUGH MOVES INTO THE WESTERN ATLANTIC.  THE
EXTRATROPICAL LOW IS FORECAST TO TURN EASTWARD IN ABOUT 72 HOURS AS
IT IS STEERED BY MID-LATITUDE WESTERLY FLOW ACROSS THE NORTH
ATLANTIC.  THE TRACK GUIDANCE IS TIGHTLY CLUSTERED AND THE NHC
FORECAST IS BASICALLY A BLEND OF THE ECMWF...GFS...AND THE FLORIDA
STATE UNIVERSITY SUPERENSEMBLE...AND VERY NEAR THE PREVIOUS OFFICIAL
FORECAST. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/2100Z 24.1N  65.8W   60 KT  70 MPH
 12H  16/0600Z 26.1N  65.2W   65 KT  75 MPH
 24H  16/1800Z 29.4N  64.0W   65 KT  75 MPH
 36H  17/0600Z 33.7N  61.4W   65 KT  75 MPH
 48H  17/1800Z 39.0N  57.0W   60 KT  70 MPH
 72H  18/1800Z 47.0N  41.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
 96H  19/1800Z 48.0N  27.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  20/1800Z 48.0N  25.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BROWN
 
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