WDXS31 PGTW 160900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (ERROL) WARNING NR 
019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.2S 119.2E
   INITIAL INTENSITY: 120 KTS
   GEOGRAPHIC REFERENCE: 281 NM NORTHWEST OF BROOME, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 37 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICT A PINHOLE, 7NM
WIDE EYE FEATURE, AND A SYMMETRICAL CENTRAL DENSE OVERCAST (CDO).
CLOUD TOP TEMPERATURES HAVE COOLED ALMOST 15C IN THE LAST SIX
HOURS, WHILE THE EYE TEMPERATURE HAS INCREASED TO 9C. DVORAK RAW-T AND 
FINAL-T VALUES HAVE INCREASED FROM T3.5 TO THE T6.5 RANGE SINCE 0000Z, 
AND MAY IN FACT BE UNDERESTIMATING THE SYSTEM A BIT DUE TO THE COMPACT 
NATURE OF THE INNER-CORE. TC 29S HAS PUT ON AN AMAZING SHOW OF 
EXPLOSIVE AND EXTREME RAPID INTENSIFICATION (ERI), INTENSIFYING AT 
LEAST 60 KNOTS OVER THE PAST TWELVE HOURS. A 160539Z AMSR2 89GHZ 
MICROWAVE IMAGE REVEALS A COMPACT MICROWAVE EYE SURROUNDED BY DEEP 
CONVECTION AND NO REAL SIGN OF A SECONDARY EYEWALL, AT LEAST NOT YET. 
THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 7NM 
EYE IN THE MSI AND THE MICROWAVE EYE. THE INITIAL INTENSITY IS 
ASSESSED WITH MEDIUM CONFIDENCE, AND COULD BE SLIGHTLY HIGHER, BASED 
ON AN AVERAGE OF THE SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES 
NOTED ABOVE. IT MUST BE SAID HOWEVER THAT WHILE THE KNES AND APRF CI
VALUES ARE LOW, THEY BOTH REPORTED DATA-T VALUES OF T6.5 BUT HELD
THE CI LOWER DUE TO CONSTRAINTS. THE OBJECTIVE VALUES ARE
SIGNIFICANTLY TOO LOW DUE TO THE UNDERPERFORMANCE OF THE TECHNIQUES
ON COMPACT TCS. THE ENVIRONMENT REMAINS FAVORABLE FOR NOW, WITH
WARM SSTS, STRONG OUTFLOW ALOFT AND LOW VWS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WEAK STEERING PATTERN WITH THE
SUBTROPICAL RIDGE (STR) EXTENSION TO THE SOUTH BEGINNING TO BREAK
DOWN. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   KNES: T6.0 - 115 KTS
   APRF: T5.0 - 90 KTS
   CIMSS SATCON: 85 KTS AT 160430Z
   CIMSS ADT: 92 KTS AT 160530Z
   CIMSS AIDT: 94 KTS AT 160530Z
   CIMSS D-MINT: 99 KTS AT 160539Z
   CIMSS D-PRINT: 91 KTS AT 160600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: ENHANCED POLEWARD OUTFLOW CHANNEL. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: AS TC 29S (ERROL) AND UNDERGONE ERI, IT HAS
ALSO BEEN SLOWING DOWN AND THE NEWEST FRAMES OF VIS SHOW THE EYE
BECOMING QUASI-STATIONARY AS THE STR TO THE SOUTH IS ALREADY
BREAKING DOWN AHEAD OF AN APPROACHING DEEP TROUGH TO THE SOUTHWEST.
TC 29S THUS APPEARS TO HAVE ALREADY REACHED THE INFLECTION POINT IN
ITS TRACK FORECAST AND SHOULD MEANDER SLOWLY IN A RATHER
UNPREDICTABLE FASHION OVER THE NEXT FEW HOURS UNDER WEAK STEERING
FLOW. A GENERAL TURN TOWARDS THE SOUTH SHOULD OCCUR OVER THE NEXT
12 HOURS, THEN A SHARP TURN SOUTHEASTWARD THROUGH TAU 24 AS THE
SYSTEM COMES UNDER THE PRIMARY STEERING INFLUENCE OF THE
STRENGTHENING GRADIENT BETWEEN THE TROUGH TO THE SOUTHWEST AND A
WEAK RIDGE TO THE NORTHEAST. AS THE SYSTEM STEADILY WEAKENS AFTER
TAU 24, IT WILL COME UNDER THE STEERING INFLUENCE OF PROGRESSIVELY
LOWER LEVELS OF THE ATMOSPHERE, THOUGH THE DEEP-LAYER FLOW PATTERN
REMAINS GENERALLY WESTERLY, WHICH WILL HELP PUSH TC 29S ONTO A
EAST-SOUTHEASTWARD TRACK TOWARDS THE COAST OF NORTHWEST AUSTRALIA
THROUGH TAU 96. LANDFALL NORTHEAST OF BROOME IS EXPECTED BY TAU 72,
AND AS THE SYSTEM WEAKENS BELOW TROPICAL STORM STRENGTH, IT WILL
TURN SHARPLY SOUTHWESTWARD ALONG THE WESTERN SIDE OF A DEVELOPING
LOW-LEVEL ANTICYCLONE OVER CENTRAL AUSTRALIA. SOME MODELS CONTINUE
TO SHOW A SHARPER AND EARLIER TURN TO THE SOUTHWEST, WHICH WOULD
KEEP THE SYSTEM OFFSHORE WHILE OTHERS TRACK IT STRAIGHT INLAND,
RESULTING IN SIGNIFICANT UNCERTAINTY IN THE LATER PORTION OF THE
FORECAST. INTENSITY-WISE, THE SYSTEM WILL LIKELY INTENSIFY A BIT
MORE, POTENTIALLY REACHING 130 KNOTS BY TAU 12. BUT THE WINDOW OF
OPPORTUNITY IS VERY SMALL, AND MID-LEVEL SHEAR PICKS UP SHARPLY AS
EARLY AS TAU 18, FOLLOWED BY A DRAMATIC INCREASE IN DEEP-LAYER
SHEAR BEGINNING AT TAU 24. THE SYSTEM WILL BECOME DECAPITATED
BEFORE TAU 36 AND RAPIDLY WEAKEN AS IT APPROACHES THE COAST OF
AUSTRALIA. EVEN IF THE SYSTEM REMAINS OFFSHORE, IT WILL STILL
WEAKEN BELOW TS STRENGTH WITHIN 96 HOURS. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN FAIRLY GOOD
AGREEMENT THROUGH TAU 48, WITH ALL MEMBERS OF CONSENSUS PACKAGE IN
CONCURRENCE ON A SLOW, NEARLY QUASI-STATIONARY MOTION FOR THE NEXT
12 HOURS BEFORE TURNING SHARPLY SOUTHEASTWARD THEREAFTER. THE
GUIDANCE DOES SPREAD OUT STEADILY AFTER THE TURN, WITH SPREAD
INCREASING TO 85NM AT TAU 48. BY TAU 72, THE SPREAD INCREASES TO
255NM AS THE EC-AIFS TURNS THE SYSTEM TO THE NORTHEAST WHILE THE
GFS TURNS SOUTHWEST IN THE VICINITY OF BROOME AND THE REMAINDER OF
THE GUIDANCE TRACKING THE SYSTEM TOWARDS CAPE LEVEQUE. THE JTWC
FORECAST IS PLACED JUST SOUTH OF THE CONSENSUS MEAN THROUGH THE
FORECAST PERIOD WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN
GENERAL AGREEMENT THAT THE SYSTEM WILL RAPIDLY WEAKEN FROM TAU 00,
THOUGH COAMPS-TC AND HWRF DISSIPATE THE SYSTEM AS EARLY AS TAU 60
WHILE THE HAFS-A KEEPS IT A TROPICAL STORM THROUGH TAU 120. THE
JTWC FORECAST DEVIATES HIGHER THROUGH TAU 12, AND THEN WEAKENS THE
SYSTEM AT A FASTER PACE THAN THE CONSENSUS MEAN THROUGH THE
REMAINDER OF THE FORECAST. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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