WTPA43 PHFO 220245
TCDCP3

HURRICANE JOVA DISCUSSION NUMBER  41
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
5 PM HST WED SEP 21 2005
 
SATELLITE LOOPS SHOW THAT HURRICANE JOVA IS BEGINNING TO FEEL THE 
EFFECTS OF SOUTHWESTERLY SHEAR. THE EYE IS BEGINNING TO CLOUD OVER 
AS THE DEEP CONVECTIVE CENTER BEGINS TO ELONGATE TOWARDS THE 
NORTHEAST. HOWEVER...INITIAL INTENSITY IS KEPT AT 100 KT BASED ON 
CURRENT INTENSITY DVORAK NUMBERS OF 5.5 FROM CPHC...JTWC AND GWC. 
SAB DERIVED A CURRENT INTENSITY DVORAK NUMBER OF 5.0. HALF OF THESE
AGENCIES IDENTIFIED A STRUCTURAL WEAKENING TREND...WITH JTWC AND SAB 
DERIVING A FINAL DVORAK T NUMBER OF 4.5. THE LONG-AWAITED WEAKENING 
OF JOVA DUE TO SHEAR SEEMS TO HAVE BEGUN. 

MODEL ENSEMBLE TRACK GUIDANCE IS CLOSELY PACKED...WITH THE PREVIOUS 
FORECAST TRACK FIRMLY ENTRENCHED WITHIN THE GUNS...GUNA AND CONU 
CLUSTER THROUGH 96 HOURS. THE ENTIRE TRACK ALSO LIES BETWEEN BAMD 
AND BAMM GUIDANCE TO THE RIGHT AND LEFT...RESPECTIVELY...WITH BAMS 
REPRESENTING THE LEFT OUTLIER. LONG RANGE POSITION AT 120 HOURS ALSO 
LOOKS REASONABLE. IT SEEMS THAT FEW...IF ANY...FORECAST TRACK 
CHANGES ARE NEEDED...SO THE CURRENT TRACK IS MOSTLY CONSTRUCTED FROM 
THE PREVIOUS TRACK...INTERPOLATED FORWARD BY SIX HOURS.

SINCE SHEARING EFFECTS APPEAR TO HAVE BEGUN...JOVA IS NOW FORECAST 
TO WEAKEN A BIT FASTER THAN BEFORE...DECREASING TO 40 KT AT 120 
HOURS DURING EXTRATROPICAL TRANSITION. JOVA MAY ACTUALLY WEAKEN 
FASTER THAN DEPICTED HERE IF UNFAVORABLE DEEP LAYER SHEAR VALUES 
SHOWN IN LATEST GFS75 GUIDANCE ALONG THE FORECAST TRACK PAN OUT. IF 
DEEP CONVECTION AROUND JOVA WERE TO COLLAPSE...THE SYSTEM WOULD 
BEGIN TO DEVIATE LEFT OF THE FORECAST TRACK AS STEERING BECOMES 
SHALLOW. 

USING THE LAST GOOD SCATTEROMETER PASS OVER JOVA...WIND RADII FOR 
ALL SPEEDS AND ALL FORECAST TIMES WERE REDUCED.

FORECASTER POWELL
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0300Z 18.4N 147.5W   100 KT
 12HR VT     22/1200Z 19.2N 148.2W    95 KT
 24HR VT     23/0000Z 20.3N 149.1W    90 KT
 36HR VT     23/1200Z 21.8N 150.1W    85 KT
 48HR VT     24/0000Z 23.8N 151.1W    75 KT
 72HR VT     25/0000Z 28.8N 152.8W    65 KT
 96HR VT     26/0000Z 34.9N 153.6W    50 KT
120HR VT     27/0000Z 42.5N 153.9W    40 KT...BECOMING EXTRATROPICAL
 
 
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