Tropical Storm RAFAEL

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TROPICAL STORM RAFAEL DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172012
1100 PM AST SUN OCT 14 2012
 
THE CLOUD PATTERN OF THE STORM HAS BECOME A LITTLE BETTER ORGANIZED
ON SATELLITE IMAGES OVER THE PAST SEVERAL HOURS...WITH MORE
DISTINCT CURVED BAND FEATURES NOTED TO THE NORTHWEST...NORTH...
NORTHEAST...AND EAST OF THE CENTER.  THE AIR FORCE HURRICANE
HUNTERS MEASURED PEAK 850 MB FLIGHT-LEVEL WINDS OF 71 KT AND AN
SFMR SURFACE WIND OF 59 KT TO THE NORTH-NORTHWEST OF THE CENTER. 
CORRECTING FOR RAINFALL REDUCES THIS SFMR VALUE TO 54 KT...BUT IT
IS PRESUMED THAT SLIGHTLY STRONGER SURFACE WINDS ARE OCCURRING OVER
THE NORTHEAST QUADRANT...SO THE CURRENT INTENSITY ESTIMATE IS
INCREASED TO 60 KT.  

RAFAEL HAS FAIRLY WELL-DEFINED UPPER-LEVEL OUTFLOW OVER THE NORTHERN
AND EASTERN PORTIONS OF ITS CIRCULATION.  ALTHOUGH THE
SOUTHWESTERLY SHEAR OVER THE CYCLONE IS LIKELY TO BE MODERATE TO
STRONG OVER THE NEXT DAY OR TWO...THE INCREASE IN ORGANIZATION AND
THE LATEST STATISTICAL-DYNAMICAL INTENSITY MODEL GUIDANCE INDICATE
THAT RAFAEL COULD STRENGTHEN SOME MORE IN THE SHORT TERM.  IN 2-3
DAYS...HOWEVER...THE SHEAR IS FORECAST TO INCREASE TO 30 TO 40 KT
AS A LARGE UPPER-TROPOSPHERIC TROUGH APPROACHES THE TROPICAL
CYCLONE...WHICH SHOULD INDUCE WEAKENING.  BY 96 HOURS...GLOBAL
MODEL OUTPUT SHOWS CONSIDERABLE COLD AIR ADVECTION OVER THE WESTERN
PORTION OF THE CIRCULATION...SO THE SYSTEM IS FORECAST TO BECOME AN
EXTRATROPICAL CYCLONE BY THAT TIME.

THE MOTION REMAINS NORTH-NORTHWESTWARD...OR 330/9...AND THE FORECAST
STEERING SCENARIO REMAINS ABOUT THE SAME AS BEFORE.  RAFAEL IS
EXPECTED TO TURN NORTHWARD AND NORTHEASTWARD WITH INCREASING
FORWARD SPEED OVER THE NEXT FEW DAYS AS IT MOVES BETWEEN A
MID-LATITUDE TROUGH AND A SUBTROPICAL HIGH PRESSURE AREA.  BY LATE
IN THE FORECAST PERIOD...GLOBAL GUIDANCE SHOWS THE EXTRATROPICAL
CYCLONE SLOWING DOWN AS IT INTERACTS WITH ANOTHER LOW OVER THE
NORTHEASTERN ATLANTIC.  THERE ARE CONSIDERABLE DIFFERENCES IN THE
FORWARD SPEED PREDICTED BY THE DYNAMICAL MODELS OVER THE NEXT 3
DAYS OR SO...WITH THE ECMWF SHOWING A SUBSTANTIALLY SLOWER MOTION
THAN MOST OF THE OTHER TRACK GUIDANCE.  THE OFFICIAL TRACK FORECAST
IS SIMILAR TO THAT FROM THE PREVIOUS ADVISORY AND LEANS TOWARD THE
LATEST GFS ENSEMBLE MEAN FORECAST. 

FORECAST POSITIONS AND MAX WINDS
 
INIT  15/0300Z 21.6N  64.8W   60 KT  70 MPH
 12H  15/1200Z 22.8N  65.6W   65 KT  75 MPH
 24H  16/0000Z 24.8N  65.9W   70 KT  80 MPH
 36H  16/1200Z 27.5N  65.0W   70 KT  80 MPH
 48H  17/0000Z 31.5N  62.6W   65 KT  75 MPH
 72H  18/0000Z 40.5N  55.0W   60 KT  70 MPH
 96H  19/0000Z 48.0N  39.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
120H  20/0000Z 49.0N  26.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER PASCH
 
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