WDPN31 PGTW 310900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (JANGMI) WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.8N 127.8E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 282 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 06W CONTINUES TO PRESENT A RAGGED, 60NM-WIDE EYE 
FEATURE, WITH A PRONOUNCED WAVENUMBER-4 ASYMMETRY AND MULTIPLE 
MESOVORTICES OBSERVED ROTATING ABOUT A CENTROID WITHIN THE EYE. A 
310530Z NOAA-20 88.2GHZ IMAGE REVEALED A NEARLY SQUARE EYEWALL 
STRUCTURE, PROVIDING HIGH CONFIDENCE IN THE WAVENUMBER-4 STRUCTURE OF 
THE INNER CORE. TO THE NORTHEAST, A PRONOUNCED ROPE CLOUD FEATURE 
EXTENDS FROM JUST NORTH OF MINAMI DAITO JIMA TO THE NORTHERN BONIN 
ISLANDS, DELINEATING THE POSITION OF THE EQUATORWARD END OF A 
STATIONARY FRONTAL BOUNDARY. ANIMATED WATER VAPOR IMAGERY DEPICTS 
INCREASING OUTFLOW, PARTICULARLY POLEWARD, FLOWING INTO THE RIGHT 
REAR ENTRANCE REGION OF A JET MAX OVER SOUTHERN JAPAN. THE INITIAL 
POSITION IS ASSESSED WITH HIGH CONFIDENCE, CO-LOCATED NEAR THE 
CENTROID OF THE MULTIPLE MESOVORTICES IN THE ANIMATED MSI. THE 
INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON A 
BLEND OF THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES NOTED 
BELOW. ENVIRONMENTAL CONDITIONS ARE MARGINALLY FAVORABLE, WITH WARM 
(BUT DECLINING) SSTS, LOW DEEP-LAYER WESTERLY SHEAR, AND INCREASING 
POLEWARD OUTFLOW ENHANCING THE MODERATE RADIAL OUTFLOW ALREADY IN 
PLACE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) POSITIONED SOUTHEAST OF HONSHU. THE SYSTEM
IS APPROACHING THE RIDGE AXIS. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 66 KTS AT 310630Z
   CIMSS ADT: 32 KTS AT 310600Z
   CIMSS AIDT: 58 KTS AT 310600Z
   CIMSS D-MINT: 70 KTS AT 310447Z
   CIMSS D-PRINT: 66 KTS AT 310630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 06W IS BEGINNING ITS GRADUAL TURN NORTHWARD 
AS IT APPROACHES THE AXIS OF THE STR TO THE EAST. THE SYSTEM WILL 
REACH THE RIDGE AXIS AND COMMENCE A NORTHEASTWARD RECURVATURE BY TAU 
24, AS IT APPROACHES OKINAWA FROM THE SOUTH. LANDFALL OVER OKINAWA IS 
PROJECTED SHORTLY AFTER TAU 24, AFTER WHICH THE SYSTEM WILL 
ACCELERATE NORTHEASTWARD, PARALLELING THE NORTHERN RYUKYU ISLANDS AND 
SKIRTING THE SOUTHERN TIP OF KYUSHU BY TAU 48. TY 06W WILL CONTINUE 
TO ACCELERATE ALONG THE TIGHT STEERING GRADIENT BETWEEN THE STR TO 
THE SOUTHEAST AND THE MID-LATITUDE WESTERLIES OVER JAPAN THROUGH TAU 
72. THE SYSTEM IS FORECAST TO PASS OVER THE SOUTHERN PORTION OF 
SAGAMI BAY AND THE APPROACHES TO TOKYO BAY, PASSING OVER THE BOSO 
PENINSULA BY TAU 72. THE SYSTEM QUICKLY PASSES YOKOSUKA AND MOVES 
BACK OVER OPEN WATERS, DECELERATING SLIGHTLY DUE TO AN INTERACTION 
WITH A GENERALLY WEAKER STEERING GRADIENT, THROUGH THE END OF THE 
FORECAST PERIOD. REGARDING INTENSITY, THE SYSTEM HAS CONSISTENTLY 
FAILED TO ACHIEVE AXISYMMETRIZATION, MAINTAINING A PERSISTENTLY HIGH 
WAVENUMBER ASYMMETRY OVER THE PAST 24 TO 36 HOURS. HOWEVER, DEEP 
CONVECTION HAS SUCCESSFULLY WRAPPED UPSHEAR AND NOW ENCOMPASSES THE 
MAJORITY OF THE CIRCULATION, AND THE RADIUS OF MAXIMUM WINDS (RMW) 
APPEARS TO BE CONTRACTING SLIGHTLY; INDICATING THAT THE SYSTEM MAY 
CONSOLIDATE FURTHER WITHIN THE NEXT 12 TO 24 HOURS. THE ENHANCED 
POLEWARD OUTFLOW WILL FACILITATE THIS, PROVIDING DYNAMIC SUPPORT TO 
DEVELOP AND MAINTAIN DEEP CONVECTION. THE FAVORABLE DEVELOPMENT 
WINDOW IS LIMITED, AS TY 06W TRANSITIONS INTO SUB-26C WATERS BY TAU 
24. THE FORECAST THUS CALLS FOR A SLIGHT INTENSIFICATION TO 75 KNOTS 
WITHIN 12 HOURS, FOLLOWED BY A GRADUAL WEAKENING BEGINNING AS THE 
SYSTEM PASSES OKINAWA AND CONTINUING THROUGH THE REMAINDER OF THE 
FORECAST PERIOD. THE SYSTEM BEGINS EXTRATROPICAL TRANSITION (ETT) 
SLIGHTLY BEFORE TAU 72, COMPLETING ETT BY TAU 96 AS THE SYSTEM 
BECOMES FULLY EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES. 

MODEL DISCUSSION: THE CONSENSUS PACKAGE IS IN VERY GOOD AGREEMENT, 
WITH MINIMAL CROSS- OR ALONG-TRACK SPREAD THROUGH TAU 48. ALL 
CONSENSUS MEMBERS, INCLUDING AVAILABLE ENSEMBLE AND MACHINE LEARNING 
(AI) MODELS, CONVERGE ON A LANDFALL OVER OKINAWA IN ABOUT 30 HOURS. 
AFTER TAU 48, THE GFS, JGSM AND NAVGEM BEGIN TO DIVERGE FROM THE 
REMAINDER OF THE CONSENSUS, DEPICTING A SLIGHTLY FLATTER TRAJECTORY 
AND INCREASING CROSS-TRACK SPREAD TO 110NM BY TAU 72. THE REMAINDER 
OF THE CONSENSUS MEMBERS ARE TIGHTLY PACKED ABOUT THE CONSENSUS MEAN, 
WITH A CROSS-TRACK SPREAD OF JUST 50NM AS THE SYSTEM REACHES ITS 
CLOSEST POINT OF APPROACH TO YOKOSUKA. ALONG-TRACK SPREAD INCREASES 
TO APPROXIMATELY 150NM BY TAU 72, WITH THE GFS AND NAVGEM EXHIBITING 
A SLOW BIASED FORWARD TRACK SPEED. THE EXPERIMENTAL MULTI-MODEL 
SUPER-ENSEMBLE MEAN IS POSITIONED PROXIMATE TO THE JTWC FORECAST 
TRACK, LENDING HIGH CONFIDENCE TO THE FORECAST. INTENSITY GUIDANCE IS 
ALSO IN GOOD AGREEMENT, THOUGH ALL MODELS EXCEPT FOR THE SHIPS-GFS, 
DEPICT A FLAT OR DECREASING INTENSITY TREND THROUGH TAU 24, 
ACCELERATING THEREAFTER. THE JTWC FORECAST IS PLACED ON TOP OF THE 
SHIPS-GFS, WHICH PEAKS AT 75 KNOTS AND THEN TRACKS THE CONSENSUS MEAN 
FROM TAU 36 TO TAU 96.

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