WDPN31 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 04W (SINLAKU) WARNING NR 
021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.3N 146.5E
   INITIAL INTENSITY: 135 KTS
   GEOGRAPHIC REFERENCE: 68 NM SOUTHEAST OF SAIPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL IMAGERY (MSI) SHOWS A SYMMETRIC 18 NM EYE
AND NEARLY SYMMETRIC CLOUD BANDS WRAPPING INTO THE CORE. A TREND OF
WARMING CLOUD TOPS HAS BEEN OBSERVED IN ANIMATED LONGWAVE IR
(DVORAK) IMAGERY OVER THE PAST 6 HOURS WITH THE COLD MEDIUM GRAY
(CMG) SHADE NO LONGER SURROUNDING THE EYE. THE 132256Z GMI 37 AND
89 GHZ MICROWAVE IMAGES SHOW EVIDENCE OF THE CONTINUING EYEWALL
REPLACEMENT CYCLE WITH A PROMINENT MOAT OF LOW BRIGHTNESS
TEMPERATURES BETWEEN THE COMPACT INNER CORE EYEWALL AND THE
DEVELOPING OUTER EYEWALL. ANIMATED RADAR IMAGERY CORROBORATES THE
MICROWAVE IMAGERY, SHOWING DISTINCT RAIN BANDS ASSOCIATED WITH THE
EYEWALL REPLACEMENT FEATURES. A 132256Z METOP-B ASCAT PASS THAT
WENT DIRECTLY OVER THE CENTER OF THE SYSTEM REVEALED A BROAD FIELD
OF GALE-FORCE WINDS WITH A DIAMETER OF ABOUT 400 NM.  AN EARLIER
132005Z RADARSAT-2 SAR PASS CAPTURED WIND SPEED MEASUREMENTS OF
137-143 KTS IN THE NORTHERN SEMICIRCLE OF THE INNER CORE, LENDING
HIGH CONFIDENCE TO THE INITIAL INTENSITY OF 135 KTS. THE INITIAL
POSITION IS LIKEWISE ASSESSED WITH HIGH CONFIDENCE BASED ON THE
ANIMATED MSI AND RADAR IMAGERY. THE ENVIRONMENT REMAINS FAVORABLE
WITH LOW VERTICAL WIND SHEAR (VWS), STRONG POLEWARD OUTFLOW ALOFT,
AND WARM SEA SURFACE TEMPERATURES. WEAK DRY AIR ENTRAINMENT FROM
THE SOUTHWEST CONSTITUTES THE ONLY MITIGATING ENVIRONMENTAL FACTOR.

INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T7.5 - 155 KTS
   RCTP: T7.5 - 155 KTS
   KNES: T7.0 - 140 KTS 
   CIMSS ADT: 137 KTS AT 140000Z
   CIMSS AIDT: 136 KTS AT 140000Z
   CIMSS D-MINT: 133 KTS AT 132028Z
   CIMSS D-PRINT: 141 KTS AT 140000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: ONGOING EYEWALL REPLACEMENT CYCLE (ERC)

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: SUPER TYPHOON (STY) 04W (SINLAKU) IS FORECAST
TO CONTINUE ON A NORTH-NORTHWESTWARD TRAJECTORY UNDER THE STEERING
INFLUENCE OF THE NER TO THE SOUTHEAST, WITH A CPA TO SAIPAN AND
TINIAN AROUND 141200Z. THE SYSTEM WILL MAKE ITS WAY AROUND THE
RIDGE AXIS THROUGH TAU 48, THEN ACCELERATE ON A NORTHEASTWARD TRACK
FOR THE REMAINDER OF THE FORECAST PERIOD AS THE NER CONTINUES TO
BUILD. EXTRATROPICAL TRANSITION IS FORECAST TO BEGIN AFTER TAU 96,
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 60. IN THE EVENT OF A SUCCESSFUL
EYEWALL REPLACEMENT, THE INNER CORE MAY UNDERGO SIGNIFICANT
RESTRUCTURING WITH A BROADENING EYE AND AN EXPANDING MAX WIND
RADIUS. 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 12 WITH A CROSS-TRACK
SPREAD OF 23 NM (EXCLUDING NAVGEM AS THE WESTERNMOST OUTLIER)
AROUND THE TIME THAT STY SINLAKU IS EXPECTED TO PASS SAIPAN AND
TINIAN. NAVGEM HAS BECOME A SIGNIFICANT OUTLIER, SUGGESTING A TRACK
MUCH FARTHER TO THE WEST THAN THE REST OF THE GUIDANCE. THE
CROSS-TRACK SPREAD INCREASES TO 240 NM BY TAU 72, THEN FURTHER TO
390 NM AT TAU 120. THE MODEL SPREAD HAS COME INTO CLOSER AGREEMENT
ABOUT THE SHARPNESS OF THE TURN AROUND THE RIDGE AXIS IN THE MOST
RECENT RUN. OUT OF THE PRIMARY MODEL GROUPING, GFS AND JGSM
COMPRISE THE WESTERNMOST TRACKS, WHILE ECMWF, ECENS, AND AIFS ARE
THE EASTERNMOST. THE JTWC FORECAST TRACK IS PLACED CLOSER TO THE
ECMWF ENSEMBLE MEAN WITH MEDIUM CONFIDENCE THROUGH TAU 72 AND LOW 
CONFIDENCE THEREAFTER. THE INTENSITY GUIDANCE AGREES ON STEADY
WEAKENING THROUGHOUT THE ENTIRE FORECAST PERIOD. COAMPS-TC CONTINUES 
TO BE THE QUICKEST TO WEAKEN THE SYSTEM TO 70 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//
NNNN