WDPN31 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.7N 144.5E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 71 NM WEST-NORTHWEST OF ANATAHAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 04W (SINLAKU) REMAINS A POWERFUL TYPHOON WITH THE
LARGE EYE MEASURING 37 NM AT 18Z. A SECOND EYE REPLACEMENT CYCLE
(ERC) HAS BEGUN AS EVIDENCED BY THE 04151136Z 37 AND 89 GHZ IMAGES
DEPICTING A SECONDARY EYEWALL IN FORMATION WITH COOLING CLOUD TOPS
PARTICULARLY ON THE WESTERN SEMI CIRCLE OF THIS FORMATION DEPICTED
VIA ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY.
ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH HIGH SEA SURFACE
TEMPERATURES (28 C TO 29 C), LOW VERTICAL WIND SHEAR (0-5 KTS), AND
STRONG RADIAL OUTFLOW ALOFT. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON EIR IMAGERY OF THE EYE FEATURE IN
CONJUNCTION WITH 04151541Z ATMS IMAGERY. THE INITIAL INTENSITY OF
115 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF
AGENCY DVORAK FIXES RANGING FROM T5.0 TO T6.5. AN UPTREND AMONGST
THE CIMSS OBJECTIVE ESTIMATES CONCURS WITH A SLIGHT INCREASE IN
INTENSITY OVER THE PAST SIX HOURS COINCIDING WITH THE CURRENT ERC
PHASE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGING POSITIONED TO THE
EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T6.5 - 127 KTS
   KNES: T6.0 - 115 KTS
   CIMSS SATCON: 109 KTS AT 151700Z
   CIMSS ADT: 92 KTS AT 151930Z
   CIMSS AIDT: 90 KTS AT 151930Z
   CIMSS D-MINT: 114 KTS AT 151911Z
   CIMSS D-PRINT: 111 KTS AT 151930Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 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 04W IS NOW BEING STEERED SLOWLY NORTHWARD
BY SUBTROPICAL RIDGING TO THE EAST OF THE SYSTEM. AS THIS STEERING
CONTINUES THE TRACK WILL SHIFT PROGRESSIVELY NORTHEASTWARD FOR THE
REMAINDER OF THE FORECAST PERIOD. A TROUGH EAST OF HONSHU IS
EXPECTED TO ENHANCE THIS TRACK MOTION BETWEEN TAU 24 AND TAU 48
RESULTING IN A SHARPER NORTHEASTWARD CURVE AS THE RIDGE WEAKENS IN
CONJUNCTION WITH MID-LATITUDE WESTERLY INTERACTION. BETWEEN TAU 72
AND TAU 120 TY 04W WILL BECOME FULLY EMBEDDED WITHIN THE
MID-LATITUDE WESTERLIES LOSING ITS TROPICAL CHARACTERISTICS AND
BEING PULLED FURTHER EASTWARD AS AN EXTRATROPICAL CIRCULATION.
INTENSITY IS EXPECTED TO SLOWLY DECREASE THEN REMAIN STEADY OVER THE
NEXT 24 HOURS AS THE SYSTEM COMPLETES THE CURRENT ERC CYCLE. AFTER
TAU 24 INTENSITY WILL MORE RAPIDLY DROP AS THE STORM TRAVELS OVER
SEA SURFACE TEMPERATURES (SST) OF BELOW 26 DEGREES CELSIUS AND THE
VERTICAL WIND SHEAR (VWS) ASSOCIATED WITH THE WESTERLIES INCREASES
TO 20-30 KTS. DRY AIR WILL INFILTRATE THE INNER CORE AS WELL
RESULTING IN THE SYSTEM COMPLETING EXTRATROPICAL TRANSITION BY TAU
120 AT 55 KT STRENGTH.

MODEL DISCUSSION: CROSS TRACK MODEL GUIDANCE SPREAD IS UP TO 90 NM
AT TAU 72 INCREASING UP TO 200 NM AT THE END OF THE FORECAST
PERIOD. THE CONSENSUS IS A MORE POLEWARD TRAJECTORY AFTER TAU 48.THE 
JTWC TRACK IS PLACED SLIGHTLY EAST OF THE MULTI MODEL CONSENSUS WITH 
HIGH CONFIDENCE UNTIL TAU 72 AND MEDIUM CONFIDENCE THEREAFTER. THE 
JTWC INTENSITY FORECAST REMAINS SLIGHTLY ABOVE THE MULTI MODEL
CONSENSUS WITH GUIDANCE POINTING TOWARDS A STEADY WEAKENING TREND
FOR THE REMAINDER OF THE FORECAST PERIOD OUTSIDE OF COAMPS-TC AND
GFS REFLECTING A SHARPER DROP IN INTENSITY. THE JTWC FORECASTED
INTENSITY IS A SLIGHTLY MORE STEADY WEAKENING TREND ACCOUNTING FOR THE
CURRENT ERC PHASE AND IS PLACED WITH MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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