WDXS33 PGTW 050900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (TALIAH) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.2S 107.4E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 571 NM NORTHWEST OF LEARMONTH, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A HIGHLY
ASYMMETRIC STRUCTURE AND A PARTIALLY EXPOSED LOW LEVEL CIRCULATION
CENTER (LLCC), DISPLACED TO THE EAST OF A STEADILY WEAKENING
CONVECTION. A WELL-TIMED 050611Z AMSR2 36GHZ IMAGE REVEALED A
WELL-DEFINED LOWER-LEVEL MICROWAVE EYE OR LOW EMISSIVITY REGION
(LER), WITH SHALLOW BANDING FEATURES WRAPPING IN FROM THE SOUTH AND
EAST. IN THE 89GHZ BAND, A WELL-DEFINED MICROWAVE EYE AND STRONG
EYEWALL LIKE FEATURES ARE EVIDENT, THOUGH THEY ARE DISPLACED 70NM
TO THE NORTHWEST, CONSISTENT WITH THE STRONG SOUTHEASTERLY SHEAR.
THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
MICROWAVE EYE IN THE 36GHZ MICROWAVE IMAGE NOTED ABOVE. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF
THE OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES OUTLINED ABOVE.
THE ENVIRONMENT IS MARGINAL AT BEST, WITH STRONG SOUTHEASTERLY
SHEAR, UPPER-LEVEL CONVERGENT FLOW AND DRY AIR INTRUSION OFFSETTING
OTHERWISE FAVORABLE SSTS AND SUPPORTIVE OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) COMPLEX EXTENDING FROM WESTERN AUSTRALIA
FAR INTO THE SOUTH INDIAN OCEAN. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T5.0 - 90 KTS
   APRF: T4.0 - 65 KTS
   CIMSS SATCON: 58 KTS AT 050600Z
   CIMSS ADT: 47 KTS AT 050600Z
   CIMSS AIDT: 58 KTS AT 050600Z
   CIMSS D-PRINT: 42 KTS AT 050600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE WESTWARD
   OTHER FACTORS: DRY MID-LEVEL AIR AND UPPER-LEVEL CONVERGENCE TO
THE EAST.

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE INTENSITY IN THE MID-RANGE
FORECAST HAS BEEN LOWERED 20 KNOTS. 

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 14S (TALIAH) IS FORECAST
TO CONTINUING TO TRACK GENERALLY WESTWARD THROUGH THE ENTIRE
FORECAST PERIOD. SOME WAVINESS IN THE TRACK IS EXPECTED AS THE
RIDGE SHIFTS SLIGHTLY OVER THE COURSE OF THE NEXT FOUR DAYS BUT
OVERALL, THE STR TO THE SOUTH WILL REMAIN THE DOMINANT STEERING
INFLUENCE UP TO TAU 72. AFTER THIS POINT, TC 14S WILL SLOW DOWN
SIGNIFICANTLY AS THE RIDGING PATTERN BREAKS DOWN DUE TO THE PASSAGE
OF A MID-LATITUDE TROUGH TO THE SOUTH, GENERATING A WEAK STEERING
ENVIRONMENT WHICH WILL PERSIST BEYOND THE END OF THE FORECAST. IN
TERMS OF INTENSITY, STRONG EASTERLY SHEAR IS FORECAST TO PERSIST
FOR THE NEXT 48 TO 60 HOURS, ACCOMPANIED BY SIGNIFICANT DRY AIR
INTRUSION, ESPECIALLY FROM THE EAST. THERE MAY BE TIMES WHEN
CONVECTION IS ABLE TO MOMENTARILY PUSH BACK AGAINST THE SHEAR, BUT
OVERALL IT IS UNLIKELY THESE CONVECTIVE BURSTS WILL SUSTAIN
THEMSELVES IN THE FACE OF 25-30 KNOT SHEAR. THE SYSTEM WILL
STEADILY WEAKEN UNDER THESE NEGATIVE INFLUENCES, DOWN TO ABOUT 50
KNOTS BY TAU 36. CONDITIONS LOOK TO IMPROVE AFTER TAU 48, WITH A
REDUCTION IN SHEAR, INCREASE IN MOISTURE AND DEVELOPMENT OF A
POLEWARD OUTFLOW CHANNEL, WHICH WILL ENABLE THE SYSTEM TO
REINTENSIFY FROM TAU 48 TO TAU 120. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72, WITH THE NAVGEM BEING THE SOLE OUTLIER. THE
REMAINDER OF THE GUIDANCE PACKAGE IS TIGHTLY CONSTRAINED TO A
CROSS-TRACK ENVELOPE OF 80NM AT TAU 72. ALONG-TRACK SPREAD BEGINS
TO INCREASE AFTER TAU 48, UP TO 135NM AT TAU 72. IN THE LONG-RANGE
PORTION OF THE FORECAST, AS THE STEERING PATTERN WEAKENS, THE
MODELS BEGIN TO QUICKLY SPREAD OUT, WITH UKMET BASED MODELS TURNING
THE SYSTEM NORTHWARD, WHILE THE GFS AND GEFS TURN IT SOUTHWARD. THE
ECMWF AND ECENS AND THE CONSENSUS MEAN MAINTAIN A MIDDLE GROUND,
GENERATING A CROSS- AND ALONG-TRACK SPREAD OF ABOUT 150NM BY TAU
120. THE JTWC FORECAST LIES ON THE NORTHERN EDGE OF THE GUIDANCE
ENVELOPE THROUGH TAU 96, THEN CLOSELY FOLLOWS THE ECWMF TRACKER
THEREAFTER. CONFIDENCE IS HIGH TO TAU 72, THEN MEDIUM TO TAU 120.
INTENSITY GUIDANCE IS IN GOOD AGREEMENT, AND ALL MODELS CONCUR ON
THE WEAKENING TREND TO TAU 48 FOLLOWED BY REINTENSIFICATION. THE
JTWC FORECAST FOLLOWS THE HAFS-A TREND LINE, AT ABOUT FIVE KNOTS
WEAKER, WITH MEDIUM CONFIDENCE. 

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