253 

WDPN31 PGTW 162100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.0N 145.0E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 42 NM WEST-NORTHWEST OF AGRIHAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 34 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 04W (SINLAKU) HAS CONTINUED TO STEADILY WEAKEN AS
EVIDENCED BY ITS COLLAPSING RAGGED EYE FEATURE AND WARMING CLOUD
TOP TEMPERATURES WITHIN CONVECTIVE BANDING DEPICTED BY ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY. SOME DRY AIR CAN BE
OBSERVED WRAPPING INTO THE CORE FROM THE WEST-SOUTHWEST.
ENVIRONMENTAL CONDITIONS REMAIN MARGINAL WITH STRONG RADIAL
OUTFLOW, LOW (5-10 KTS) VERTICAL WIND SHEAR (VWS), AND SEA SURFACE
TEMPERATURES (SST) BETWEEN 26 C AND 27 C. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON EIR IMAGERY OF THE RAGGED EYE
FEATURE. THE INITIAL INTENSITY OF 85 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON AN EARLIER  04160824Z SAR PASS ALONG WITH
SUBJECTIVE AND OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: 04160824Z SAR DATA

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

AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 102 KTS AT 161830Z
   CIMSS ADT: 87 KTS AT 161900Z
   CIMSS AIDT: 83 KTS AT 161900Z
   CIMSS D-MINT: 98 KTS AT 161854Z
   CIMSS D-PRINT: 94 KTS AT 161900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 05-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY SINLAKU WILL CONTINUE TRACKING TO THE
NORTHEAST FOR THE REMAINDER OF THE FORECAST PERIOD. AS THE SYSTEM
CONTINUES AROUND THE NORTHWESTERN PERIPHERY OF RIDGING CENTERED TO
THE SOUTHEAST THE TRACK WILL BECOME INCREASINGLY INFLUENCED BY A
TROUGH PASSING TO THE NORTH AND UPPER-LEVEL WESTERLIES, RESULTING
IN AN INCREMENTALLY INCREASING TRANSLATIONAL SPEED. FORECASTED
INTENSITIES ARE EXPECTED TO CONTINUE STEADILY DECREASING OVER THE
NEXT TWELVE HOURS. AFTERWARD, THE WEAKENING TREND WILL BE STEEPER
AS THE CIRCULATION LOSES ENERGY FROM PROLONGED EXPOSURE TO COOLER
SEA SURFACE TEMPERATURES (24 C TO 25 C), INCREASED VERTICAL WIND
SHEAR (30+ KTS AT TAU 48), AND INCREASED DRY AIR ENTRAINMENT FROM
UPPER-LEVEL WESTERLY INTERACTION. THE SYSTEM IS EXPECTED TO START
EXTRATROPICAL TRANSITION BETWEEN TAU 36 AND TAU 48. EXTRATROPICAL
TRANSITION IS FORECASTED TO BE COMPLETE BY TAU 72 WITH 50 KT
INTENSITY.

MODEL DISCUSSION: CROSS TRACK SPREAD AMONGST THE MULTI MODEL
CONSENSUS IS UNDER 50 NM THROUGHOUT THE FORECAST PERIOD. THE JTWC
FORECASTED TRACK IS PLACED CLOSE TO THE MULTI MODEL CONSENSUS WITH
HIGH CONFIDENCE. INTENSITY GUIDANCE IS SPREAD UP TO 20 KTS BY TAU
72 WITH ALL DEPICTIONS REFLECTING A STEADY WEAKENING TREND
THROUGHOUT THE FORECAST. THE JTWC FORECASTED INTENSITY IS PLACED
WITH MEDIUM CONFIDENCE, SLIGHTLY HIGHER THAN THE CONSENSUS UNTIL
TAU 24 AND DROPPING SLIGHTLY UNDER THE CONSENSUS THEREAFTER.

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