WDPN31 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 04W (SINLAKU) WARNING NR 
020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.7N 147.0E
   INITIAL INTENSITY: 145 KTS
   GEOGRAPHIC REFERENCE: 141 NM EAST OF NAVSTA GUAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 43 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
SYMMETRIC EYE FEATURE AND A SLIGHT DEFORMATION BEGINNING TO DEVELOP
IN THE NORTHERN SEMICIRCLE. ANIMATED RADAR IMAGERY SHOWS A DEFINED
OUTER EYEWALL ENCIRCLING THE SMALLER INNER EYEWALL. ADDITIONALLY, A
131758Z F18 SSMIS 91 GHZ MICROWAVE IMAGE SHOWS INDICATIONS OF AN
ONGOING ERC EVENT WITH A PROMINENT MOAT FEATURE SURROUNDING THE
INNER EYEWALL. POLEWARD AND EQUATORWARD OUTFLOW CHANNELS ARE
EVIDENT IN ANIMATED WATER VAPOR IMAGERY. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED EIR AND RADAR
IMAGERY. THE INITIAL INTENSITY OF 145 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW. THE ENVIRONMENT REMAINS FAVORABLE
WITH LOW VERTICAL WIND SHEAR (VWS), HIGH SEA SURFACE TEMPERATURES,
AND VERY GOOD OUTFLOW ALOFT. A SMALL AMOUNT OF DRY AIR ENTERING
FROM THE SOUTHEAST CONSTITUTES THE ONLY MITIGATING ENVIRONMENTAL
FACTOR.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF AN EXTENSION OF
THE NEAR-EQUATORIAL RIDGE TO THE SOUTHEAST 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.5 - 155 KTS
   RJTD: T7.5 - 155 KTS
   RCTP: T7.5 - 155 KTS
   KNES: T7.0 - 140 KTS 
   CIMSS SATCON: 140 KTS AT 131800Z
   CIMSS ADT: 152 KTS AT 131800Z
   CIMSS AIDT: 148 KTS AT 131800Z
   CIMSS D-MINT: 145 KTS AT 131620Z
   CIMSS D-PRINT: 142 KTS AT 131800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: ONGOING EYEWALL REPLACEMENT CYCLE (ERC)

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: AFTER TAU 48, A SHARPER RECURVE TO
THE NORTHEAST IS REFLECTED IN THIS JTWC TRACK FORECAST.

FORECAST DISCUSSION: SUPER TYPHOON (STY) 04W (SINLAKU) IS FORECAST
TO TRACK NORTH-NORTHWESTWARD THROUGH TAU 48 AS IT APPROACHES THE
MARIANA ISLANDS AND THE AXIS OF THE STEERING RIDGE TO THE
SOUTHEAST. ALONG THIS TRACK, THE CPA TO TINIAN AND SAIPAN IS
FORECAST TO OCCUR AROUND 141400Z. IT HAS BECOME APPARENT THAT THE
NER TO THE SOUTHEAST HAS TAKEN CONTROL OF THE STEERING ENVIRONMENT
AS THE SUBTROPICAL RIDGE TO THE WEST WEAKENS AND RETREATS WESTWARD.
AFTER TAU 48, STY SINLAKU WILL ROUND THE RIDGE AXIS ON A NORTHWARD
TRACK THAT TURNS NORTHEASTWARD AND ACCELERATES THROUGH THE
REMAINDER OF THE FORECAST PERIOD. EXTRATROPICAL TRANSITION IS
FORECAST TO BEGIN NEAR TAU 120 WITH COMPLETION EXPECTED BEYOND THE
CURRENT FORECAST TIMEFRAME. A STEADY WEAKENING TREND ATTRIBUTED TO
THE ONGOING EYEWALL REPLACEMENT CYCLE, WEAK DRY AIR ENTRAINMENT,
AND WEAKENING OUTFLOW SUPPORT IS FORECAST THROUGH TAU 72. FURTHER
STEADY WEAKENING AFTER TAU 72 IS FORECAST IN THE PRESENCE OF
LOWERING SEA SURFACE TEMPERATURES AND INCREASING WESTERLY VWS AS
THE SYSTEM APPROACHES THE POLAR FRONT JET.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT WITH
THE NORTH-NORTHWESTWARD TRACK THROUGH TAU 24 WITH A CROSS-TRACK
SPREAD OF 55 NM (EXCLUDING NAVGEM AS THE WESTERNMOST OUTLIER) AFTER
PASSING OVER THE NORTHERN MARIANA ISLANDS. THE CROSS-TRACK SPREAD
INCREASES AFTER TAU 24 TO 240 NM AT TAU 72 AND 480 NM AT TAU 120.
THE TIMING AND SHARPNESS OF TURNING ROUND THE RIDGE AXIS APPEAR TO
BE THE PRIMARY FACTOR IN MODEL DISAGREEMENT AFTER TAU 48. THE ECMWF
AND EC-AIFS COMPRISE THE EASTERNMOST MODELS WHILE NAVGEM, JGSM, AND
GFS ARE THE WESTERNMOST. THE JTWC TRACK FORECAST IS PLACED CLOSE TO
THE MODIFIED CONSENSUS WITH MEDIUM CONFIDENCE THROUGH TAU 72 AND
LOW CONFIDENCE THEREAFTER. THE INTENSITY GUIDANCE AGREES ON
WEAKENING THROUGHOUT THE ENTIRE FORECAST PERIOD. COAMPS-TC IS THE
QUICKEST TO WEAKEN TO 75 KTS AT TAU 36 WHILE HAFS-A AND HWRF AGREE
ON A MORE GRADUAL WEAKENING TREND. THE JTWC INTENSITY FORECAST IS
PLACED CLOSE TO THE HAFS-A AND HWRF SOLUTIONS WITH OVERALL MEDIUM
CONFIDENCE.

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