445 

WDPN31 PGTW 170900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 034//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.0N 145.8E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 381 NM SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE EYE OF
TYPHOON (TY) 04W (SINLAKU) CONTINUING TO FILL AND ELONGATE
SLIGHTLY, SHOWING A POSSIBLE TILT OF THE SYSTEM BY SOLELY ANALYZING
VISIBLE IMAGERY INDICATES THE CENTER SLIGHTLY EAST TO THAT OF THE
LOW LEVEL CIRCULATION CENTER (LLCC) LOCATED ON IR IMAGERY. THE
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE
STILL VISIBLE EYE ON IR ALONG WITH THE AGENCY SATELLITE FIXES.
ENVIRONMENTAL CONDITIONS CONTINUE TO DETERIORATE AS TY 04W IS
ACTIVELY CROSSING THE 26 C SEA SURFACE TEMPERATURE (SST) ISOTHERM
AS WELL AS ENCOUNTERING LOW TO MODERATE (15-20 KTS) VERTICAL WIND
SHEAR (VWS) AND DRY AIR ENTRAINMENT. THE INITIAL INTENSITY IS
ASSESSED WITH MEDIUM CONFIDENCE, AS ALL AGENCY DVORAK FIXES LISTED
BELOW ARE IN GOOD AGREEMENT, HOWEVER, THE OBJECTIVE AIDS HAVE A
WIDER SPREAD.

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 SATCON: 92 KTS AT 170520Z
   CIMSS ADT: 84 KTS AT 170700Z
   CIMSS AIDT: 81 KTS AT 170700Z
   CIMSS D-MINT: 90 KTS AT 170608Z
   CIMSS D-PRINT: 85 KTS AT 170630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 15-20 KTS
   SST: 26-27 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: TY 04W IS FORECAST TO CONTINUE A NORTHEASTWARD
TRACK AS IT CONTINUES TO BE STEERED BY THE STRONG RIDGING CENTERED
TO THE SOUTHEAST. BY TAU 36, IT IS FORECAST TO BE UNDER THE
INFLUENCE OF A HIGH (30+ KTS) VWS, AND LOCATED FULLY POLEWARD OF
THE 26 C ISOTHERM, AND CONTINUING TO ENTRAIN DRY AIR. AS SUCH,
EXTRATROPICAL TRANSITION (ETT) WILL BEGIN AT THIS TIME, AND IS
EXPECTED TO COMPLETE BY TAU 48. TRANSLATIONAL SPEED OF TY SINLAKU
IS FORECAST TO INCREASE WITH EACH TAU, WHILE INTENSITY IS FORECAST
TO STEADILY DECREASE, WITH A SHARPER DROP BETWEEN TAU 36 AND 48 AS
ETT TAKES HOLD, COMPLETING THE TRANSITION WITH AN INTENSITY OF 55
KTS.

MODEL DISCUSSION: ALL MODEL TRACK GUIDANCE IS IN STRONG AGREEMENT
FOR THE REMAINDER OF THE FORECAST PERIOD, WITH TY 04W CONTINUING
ITS NORTHEASTWARD MOTION. OF NOTE, THE LATEST POSITION OF TY
SINLAKU SHOWS A SHARPER TURN TO THE EAST THAN THE MULTI-MODEL
CONSENSUS, AS INDICATED BY CURRENTLY ANALYZED POSITION. DUE TO THE
AGREEMENT BETWEEN ALL AIDS, THE JTWC FORECAST TRACK IS PLACED WITH
HIGH CONFIDENCE, SLIGHTLY TO THE EAST OF THE CONSENSUS. THE JTWC
INTENSITY FORECAST IS ALSO PLACED WITH HIGH CONFIDENCE, WITH A
SLIGHTLY LESS AGGRESSIVE WEAKENING TREND THAN THE MULTI-MODEL MEAN
GUIDANCE.

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