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HURRICANE NARDA DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT SUN OCT 21 2001

RECENT VISIBLE IMAGERY HAS SHOWN OCCASIONAL HINTS OF AN EYE AND A 
BANDING FEATURE WRAPPING MORE THAN 100 PER CENT AROUND THE CENTER.  
BOTH TAFB MIAMI AND SAB WASHINGTON DETERMINED A DATA T-NUMBER OF 
4.0...FOR AN INTENSITY ESTIMATE OF 65 KNOTS.  ON THIS BASIS...NARDA 
IS UPGRADED TO A HURRICANE.  THE UPPER-LEVEL OUTFLOW CONTINUES TO 
LOOK FAIRLY IMPRESSIVE...ALTHOUGH WEAK TO THE SOUTH...AND SHEAR IS 
NOT PROHIBITIVELY STRONG AT THE MOMENT.  HOWEVER...NUMERICAL 
GUIDANCE INDICATES A LARGE INCREASE OF WESTERLY SHEAR OVER NARDA IN 
1-2 DAYS.  SOME MORE STRENGTHENING MAY OCCUR IN THE SHORT TERM...BUT 
LATER IN THE PERIOD THE CYCLONE IS LIKELY TO BE WEAKENING.  THE 
INTENSITY FORECAST IS SIMILAR TO THE TRENDS INDICATED BY THE LATEST 
SHIPS GUIDANCE.  AS NOTED EARLIER...THE GFDL MODEL SHOWS MORE 
STRENGTHENING THAN OTHER MODELS...BUT IT HAS A WELL-KNOWN TENDENCY 
TO OVER-INTENSIFY SYSTEMS IN CASES OF STRONG SHEAR.

THE MOTION...TRACK FORECAST...AND SYNOPTIC REASONING ARE BASICALLY 
UNCHANGED FROM THE PREVIOUS ADVISORY PACKAGE.  A MID-TROPOSPHERIC 
ANTICYCLONE TO THE NORTH OF NARDA SHOULD BE MAINTAINED FOR THE NEXT 
SEVERAL DAYS.  THIS MEANS THAT THE WEST-NORTHWESTWARD TRACK IS 
LIKELY TO CONTINUE THROUGHOUT THE FORECAST PERIOD.  THE OFFICIAL 
TRACK FORECAST IS A BLEND OF THE DYNAMICAL GUIDANCE...FASTER THAN 
THE GFDL FORECAST BUT SLOWER THAN SHOWN BY THE LATEST AVN OUTPUT. 

THE 34-KNOT WIND RADII HAVE BEEN INCREASED SOMEWHAT BASED ON A 
RECENT QUIKSCAT PASS OVER NARDA.
 
FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     21/2100Z 14.2N 131.2W    65 KTS
12HR VT     22/0600Z 15.0N 132.9W    70 KTS
24HR VT     22/1800Z 16.0N 135.4W    70 KTS
36HR VT     23/0600Z 17.0N 138.0W    65 KTS
48HR VT     23/1800Z 18.0N 140.5W    55 KTS
72HR VT     24/1800Z 19.0N 145.0W    40 KTS
 
 
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