905 

WDPN31 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 035//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.8N 146.2E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 362 NM SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS THE
REMNANT EYE FEATURE OF TYPHOON (TY) 04W (SINLAKU) AS IT CONTINUES
TO LOSE STRENGTH. THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON EXTRAPOLATION FROM BOTH A 170833Z RCM-3 SAR
PASS AND A 171116Z METOP-C ASCAT PASS BOTH DEPICTING THE LOW-LEVEL
CIRCULATION CENTER (LLCC). THE INITIAL INTENSITY IS ALSO ASSESSED
WITH HIGH CONFIDENCE AND IS BASED ON THE MAXIMUM WIND SPEEDS FROM
THE SAME SAR PASS BEING 86 KTS, AND THE CLOS CONSENSUS OF BOTH THE
AGENCY DVORAK FIXES AND OBJECTIVE AIDS LISTED BELOW. ENVIRONMENTAL
ANALYSIS REVEALS WORSENING CONDITIONS FOR TY 04W AS IT ENTERS
COOLING (25-26 C) SEA SURFACE TEMPERATURES (SSTS), LOW TO MODERATE
(15-20 KTS) VERTICAL WIND SHEAR (VWS), AND CONTINUOUS DRY AIR
ENTRAINMENT.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) CENTERED TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 84 KTS AT 171200Z
   CIMSS AIDT: 74 KTS AT 171200Z
   CIMSS D-PRINT: 75 KTS AT 171200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 15-20 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY SINLAKU IS FORECAST TO CONTINUE ON A
NORTHEASTWARD TRACK FOR THE DURATION OF THE FORECAST PERIOD, BEING
STEERED BY THE STRONG RIDGE CENTERED TO ITS SOUTHEAST UNTIL IT
TRAVELS POLEWARD ENOUGH TO BECOME EMBEDDED UNDERNEATH THE
UPPER-LEVEL WESTERLIES. TY 04W IS FORECAST TO BEGIN EXTRATROPICAL
TRANSITION (ETT) AROUND TAU 36, AS IT HAS ALREADY CROSSED THE 26 C
ISOTHERM AND IS FORECAST TO BEGIN EXPERIENCING HIGH (30+ KTS) VWS
AT TAU 24. BY TAU 48, TY SINLAKU WILL BE UNDER 40+ KTS OF VWS, AND
WILL HAVE COMPLETED THE ETT. THE INTENSITY FORECAST WAS HELD THE
SAME AS PREVIOUS FORECAST, WITH STEADY WEAKENING AND A SLIGHTLY
STRONGER DROP DURING THE PERIOD OF ETT, AND A FORECAST TERMINAL
INTENSITY OF 55 KTS.

MODEL DISCUSSION: DESPITE THE SLIGHT EASTWARD WOBBLE WITNESSED
DURING THE PREVIOUS FORECAST PERIOD, THE CURRENT ANALYZED POSITION
IS IN GOOD AGREEMENT WITH ALL MODEL TRACK GUIDANCE HOLDING A
GENERALLY NORTH-NORTHEASTWARD TRACK. NAVGEM REMAINS A SLIGHT
OUTLIER TO THE WEST, WITH THE WIDEST GUIDANCE CROSS-TRACK SPREAD
BEING 62 NM AT THE END OF THE FORECAST PERIOD. AS SUCH, THE JTWC
FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE, SLIGHTLY EASTWARD OF
THE MULTI-MODEL CONSENSUS TO ACCOUNT FOR THE SPREAD OF NAVGEM. THE
JTWC INTENSITY FORECAST IS ALSO PLACED WITH HIGH CONFIDENCE AND
ABOVE THE MULTI-MODEL CONSENSUS, BUT FOLLOWING THE SAME WEAKENING
TREND, AND IN CLOSE AGREEMENT WITH THE INTENSITIES OF HAFS WHICH IS
NOW DISPLAYING A MORE GRADUAL WEAKENING TREND FOR THE REMAINDER OF
THE JTWC FORECAST PERIOD.

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