WDPN31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.4N 144.8E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 431 NM SOUTH-SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
(TY) 04W (SINLAKU) CONTINUING TO LOSE ITS DEFINED EYE FEATURE AS DRY
AIR WRAPS INTO THE MAIN CONVECTIVE BANDS. OTHER ENVIRONMENTAL
FACTORS REMAIN MARGINAL AND ARE CHARACTERIZED BY GOOD RADIAL
OUTFLOW, LOW (5-10 KTS) VERTICAL WIND SHEAR (VWS), AND WARM (27-28
C) SEA SURFACE TEMPERATURES (SST). HOWEVER, THIS HAS NOT BEEN ENOUGH
TO OVERCOME THE STEADY WEAKENING OF TY 04W. INTENSITY HAS DROPPED
TO 90 KTS AND IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AGREEMENT
BETWEEN ALL AGENCY DVORAK FIXES LISTED BELOW AS WELL AS OBJECTIVE
AIDS. THE INITIAL POSITION HAS BEEN ASSESSED WITH HIGH CONFIDENCE
BASED ON THE ANIMATED INFRARED SATELLITE IMAGERY.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE CENTERED
SOUTHEAST OF THE SYSTEM

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   CIMSS ADT: 97 KTS AT 161200Z
   CIMSS AIDT: 88 KTS AT 161200Z
   CIMSS D-PRINT: 90 KTS AT 161300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: AS THE NEAR EQUATORIAL RIDGE (NER) CENTERED TO
THE SOUTHEAST OF TY 04W STRENGTHENS, IT INCREASES ITS INFLUENCE ON
THE STEERING OF THE SYSTEM, AS SEEN IN THE FORECAST, WITH THE TRACK
BEGINNING TO TURN MORE SHARPLY TOWARDS THE NORTHEAST. TY 04W IS
ALSO FORECAST TO BEGIN INCREMENTALLY INCREASING IN TRANSLATIONAL
SPEED, DUE TO ITS IMMINENT EXTRATROPICAL TRANSITION (ETT),
BEGINNING AT TAU 48 AND COMPLETING BY TAU 72. HAFS SST ANALYSIS
SHOWS A BROAD AREA OF UPWELLING ASSOCIATED WITH THE WAKE OF THE
SYSTEM, AS IT NEARS THE 26 C ISOTHERM WITHIN THE NEXT 24 HOURS,
DEMONSTRATING A LOW OCEAN HEAT CONTENT FURTHERING THE WEAKENING IN
INTENSITY. IN ADDITION TO THE COOLING SSTS, TY 04W WILL ENCOUNTER
HIGH (30+ KTS) VWS BEGINNING AT TAU 48 AND INCREASING BEYOND THAT
AS TY SINLAKU BECOMES EMBEDDED UNDER THE UPPER-LEVEL WESTERLIES.
THE SYSTEM IS STILL FORECAST TO BE AT AN INTENSITY OF 55 KTS AS IT
COMPLETES ETT.


MODEL DISCUSSION: THE JTWC TRACK FORECAST IS LAID WITH HIGH
CONFIDENCE AS ALL OBJECTIVE AIDS ARE IN GOOD AGREEMENT, WITH NAVGEM
TEMPORARILY SHIFTING SLIGHTLY AWAY FROM THE MEAN BETWEEN TAUS 36
AND 48, CAUSING THE LARGEST CROSS-TRACK SPREAD OF 65 NM. OTHERWISE,
ALL MODEL TRACK PREDICTIONS ARE TIGHTLY PACKED FOR THE REMAINDER OF
THE FORECAST PERIOD. IN TERMS OF INTENSITY, ALL GUIDANCE DISPLAYS
STEADY DROP IN INTENSITY, WITH COUPLED AND STATISTICAL-DYNAMICAL
MODELS ALIKE BEING IN GOOD AGREEMENT FOR THE FORECAST PERIOD. THE
JTWC INTENSITY FORECAST LIES SLIGHTLY ABOVE THE MULTI-MODEL
CONSENSUS WITH AN OVERALL HIGH CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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