WDPN31 PGTW 150300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.6N 145.2E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 42 NM NORTHWEST OF SAIPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE FINAL
PHASE OF THE EYEWALL REPLACEMENT CYCLE (ERC) AS THE REMNANTS OF THE
INNER EYE ARE ALMOST COMPLETELY INDISCERNIBLE. A 142052Z WSFM 89
GHZ MICROWAVE IMAGE REVEALED A SLIGHT WEAKNESS IN THE WESTERN
SEMICIRCLE OF THE NEWLY DEVELOPED EYEWALL AND NO REMAINING
SIGNATURE OF THE PREVIOUS EYEWALL. A STABLE DRY AIR MASS TO THE
WEST OF THE CYCLONE IS ALSO VISIBLE IN THE MSI AND HAS STARTED TO
INTRUDE THROUGH THE OUTER BANDS OF THE SOUTHEAST QUADRANT. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
BROADENING EYE FEATURE IN THE ANIMATED MSI. THE INITIAL INTENSITY
OF 110 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON THE SPREAD OF
AGENCY DVORAK FIXES AND A LACK OF RECENT WIND SPEED DATA. THE
ENVIRONMENT IS MARGINALLY FAVORABLE DESPITE THE WEAK DRY AIR
ENTRAINMENT, WITH HIGH SEA SURFACE TEMPERATURES (SST), LOW VERTICAL
WIND SHEAR (VWS), AND MODERATE RADIAL OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NORTHWARD EXTENSION OF THE
NEAR-EQUATORIAL RIDGE TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.5 - 127 KTS
   RCTP: T6.5 - 127 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 122 KTS AT 142300Z
   CIMSS ADT: 112 KTS AT 150000Z
   CIMSS AIDT: 111 KTS AT 150000Z
   CIMSS D-PRINT: 109 KTS AT 150000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: WEAK DRY AIR ENTRAINMENT FROM THE WEST

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: FORECAST DISCUSSION: TYPHOON (TY) 04W
(SINLAKU) IS FORECAST TO ARC TOWARD A NORTHWARD, THEN NORTHEASTWARD
RECURVING TRACK THROUGH TAU 48 AS IT ROUNDS THE RIDGE AXIS OF THE
NER EXTENSION TO THE EAST. AFTER TAU 48, THE EASTERN RIDGE
EXTENSION BUILDS AND MIGRATES WESTWARD, EVENTUALLY ANCHORING TO THE
SOUTH OF 04W. A COMBINATION OF THE STEERING RIDGE AND PROXIMITY TO
THE MIDLATITUDE WESTERLIES WILL CAUSE TY SINLAKU TO ACCELERATE IN A
NORTHEASTWARD, THEN EAST-NORTHEASTWARD DIRECTION THROUGH THE
REMAINDER OF THE FORECAST PERIOD. THE SYSTEM IS EXPECTED TO BEGIN
EXTRATROPICAL TRANSITION AROUND TAU 96 AND BECOME FULLY
EXTRATROPICAL AROUND TAU 120 AS THE VORTEX BECOMES EMBEDDED WITHIN
THE STRONG UPPER-LEVEL WESTERLIES AND GAINS BAROCLINICITY. IN TERMS
OF INTENSITY, SINLAKU IS FORECAST TO CONTINUE A STEADY WEAKENING
TREND IN THE NEAR TERM AS A RESULT OF THE ERC AND WEAK DRY AIR
ENTRAINMENT. FURTHER WEAKENING THROUGH THE END OF THE FORECAST
PERIOD WILL BE ENABLED BY COOLING SEA SURFACE TEMPERATURES (20-21 C
BY TAU 120), INCREASING WESTERLY VWS (45-50 KTS BY TAU 120), AND
INCREASING DRY AIR ENTRAINMENT.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT ABOUT
THE RECURVING SCENARIO, WITH A CROSS-TRACK SPREAD OF 180 NM AT TAU
72 AND 220 NM AT TAU 120. THERE IS A NOTABLE DISAGREEMENT IN THE
ALONG-TRACK SPEED, WITH GFS AS THE SLOWEST, AIFS AS THE FASTEST,
AND THE REMAINDER OF GUIDANCE SCATTERED IN BETWEEN. AS A RESULT, THE
ALONG-TRACK SPREAD IS 365 NM AT TAU 120. THE JTWC TRACK FORECAST IS
PLACED NEAR THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE THROUGH
TAU 72 AND MEDIUM CONFIDENCE THEREAFTER. MODEL INTENSITY GUIDANCE
AGREES ON THE WEAKENING TREND THROUGHOUT THE FORECAST PERIOD.
COAMPS-TC IS AN OUTLIER WITH A MUCH FASTER RATE OF WEAKENING THAN
THE REMAINDER OF GUIDANCE, WHICH REMAINS CLOSE TO THE CONSENSUS.
THE JTWC INTENSITY FORECAST IS PLACED SLIGHTLY HIGHER THAN THE
MULTI-MODEL CONSENSUS THROUGH TAU 24, THEN CLOSE TO THE CONSENSUS
FOR THE REMAINDER OF THE FORECAST WITH OVERALL 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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