WDPN31 PGTW 311500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (JANGMI) WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.8N 127.7E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 222 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 06W HAS MAINTAINED A CONSISTENT STRUCTURAL APPEARANCE 
OVER THE PAST 24 HOURS, CHARACTERIZED BY A LARGE, RAGGED EYE WITH 
MULTIPLE MESOVORTICES ROTATING CYCLONICALLY ALONG THE INNER EDGE OF 
THE EYEWALL. SIX HOURS AGO, VISIBLE AND MICROWAVE IMAGERY SUPPORTED 
THE ANALYSIS OF AT LEAST FOUR MESOVORTICES WITHIN THE EYE. 
CONCURRENTLY, THE MOST RECENT SHORTWAVE INFRARED (SWIR) ANIMATIONS, 
ALONG WITH A 310938Z RCM-3 SAR PASS AND A 310927Z WSF-M 37GHZ IMAGE, 
INDICATE THAT THE SYSTEM HAS ACHIEVED A DEGREE OF STRUCTURAL 
AXISYMMETRIZATION, WITH ONLY TWO MESOVORTICES NOW EVIDENT. ANIMATED 
WATER VAPOR IMAGERY DEPICTS A MODERATELY STRONG POLEWARD OUTFLOW 
CHANNEL, FLOWING INTO THE RIGHT REAR ENTRANCE REGION OF A JET MAX 
OVER CENTRAL HONSHU. TO THE NORTHEAST, ANIMATED SWIR AND A 311243Z 
ASCAT PASS REVEAL A SHEAR LINE POSITIONED FROM JUST NORTH OF MINAMI 
DAITO JIMA EASTWARD TO NEAR THE NORTHERN BONIN ISLANDS, WHERE IT 
TRANSITIONS TO A STATIONARY FRONTAL BOUNDARY. THE INITIAL POSITION IS 
ASSESSED WITH HIGH CONFIDENCE, AT THE CENTROID OF THE TWO PRIMARY 
MESOVORTICES WITHIN THE EYE AS DEPICTED IN THE SWIR IMAGERY. THE 
INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE, BIASED SLIGHTLY 
HIGHER THAN THE BULK OF THE AGENCY SUBJECTIVE AND OBJECTIVE INTENSITY 
ESTIMATES IN LIGHT OF THE SAR PASS, WHICH MEASURED A MEAN VMAX OF 74 
KNOTS. ENVIRONMENTAL CONDITIONS ARE MARGINALLY FAVORABLE, WITH 
DECLINING SSTS OFFSET BY ENHANCED OUTFLOW ALOFT AND LOW VWS.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: THE SYSTEM IS APPROACHING THE AXIS OF
THE SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE EAST. 

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 ADT: 32 KTS AT 311200Z
   CIMSS AIDT: 56 KTS AT 311240Z
   CIMSS D-MINT: 71 KTS AT 310929Z
   CIMSS D-PRINT: 64 KTS AT 311240Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 0-5 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE DUAL-CHANNEL

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: TY 06W HAS TURNED ONTO A NORTHWARD HEADING,
WHILE SLOWING SLIGHTLY, AS IT APPROACHES THE AXIS OF THE STR
CENTERED SOUTHEAST OF HONSHU. THE SYSTEM IS FORECAST TO TRACK
NORTHWARD AT ROUGHLY THE SAME PACE FOR THE NEXT 12 HOURS AS IT
CROSSES THE RIDGE AXIS, BEFORE TURNING NORTHEASTWARD AND BEGINNING
TO ACCELERATE. TY 06W IS PROJECTED TO MAKE LANDFALL OVER OKINAWA 
WITHIN THE NEXT 18-20 HOURS, SUBSEQUENTLY TRACKING NORTHEASTWARD 
ALONG THE RYUKYU CHAIN THROUGH TAU 24. THE SYSTEM THEN CONTINUES TO 
ACCELERATE NORTHEASTWARD PARALLEL TO THE NORTHERN RYUKYU CHAIN BEFORE 
PASSING SOUTH OF KYUSHU AND SHIKOKU BY TAU 48. THE SYSTEM ATTAINS ITS 
MAXIMUM FORWARD SPEED BETWEEN TAU 48 AND TAU 72 AS IT IS STEERED 
NORTHEASTWARD ALONG THE TIGHT GRADIENT BETWEEN THE STR TO THE SOUTH 
AND THE MID-LATITUDE WESTERLIES TO THE NORTH. TY 06W IS FORECAST TO 
MAKE A SECOND LANDFALL ALONG THE SOUTHERN PORTION OF THE IZU 
PENINSULA BEFORE RAPIDLY TRANSITING OVER THE SOUTHERN APPROACHES TO 
TOKYO BAY AND YOKOSUKA PROXIMATE TO TAU 60. THE SYSTEM RAPIDLY 
DECELERATES AFTER TAU 72, AS THE STEERING GRADIENT COLLAPSES DUE TO 
THE STR DISPLACING SOUTHWARD AND THE REMNANT LOW TRANSLATING BENEATH 
AN UPPER-LEVEL LOW. REGARDING INTENSITY, THE SYSTEM HAS REACHED ITS 
PEAK INTENSITY AND IS FORECAST TO MAINTAIN THIS INTENSITY FOR 12 
HOURS BEFORE BEGINNING A STEADY WEAKENING PHASE FROM TAU 12 ONWARDS. 
TY 06W WILL MOVE OVER A SHARP SST GRADIENT AND INTO SUB-26C WATERS 
WITHIN THE NEXT 12 HOURS, WHICH WILL INITIATE THE WEAKENING PHASE. 
MORE RAPID WEAKENING WILL ENSUE AFTER TAU 24 AS WESTERLY SHEAR 
RAPIDLY INTENSIFIES. THE SYSTEM IS PROJECTED TO UNDERGO VERTICAL 
DECOUPLING NEAR TAU 48 DUE TO STRONG SHEAR; HOWEVER, THE ASSOCIATED 
WIND FIELD WILL REMAIN ROBUST AS THE REMNANT TRANSLATES POLEWARD. 
EXTRATROPICAL TRANSITION BEGINS AROUND TAU 60, AND WILL COMPLETE NO 
LATER THAN TAU 96. 

MODEL DISCUSSION: THE CONSENSUS PACKAGE REMAINS IN TIGHT AGREEMENT
THROUGH TAU 48, WITH MINIMAL CROSS- OR ALONG-TRACK SPREAD THROUGH
THIS TIME. ALL DETERMINISTIC, AI-BASED AND ENSEMBLE MEMBERS CONCUR
ON A LANDFALL ON OKINAWA ISLAND SAVE FOR THE HWRF, WHICH DEPICTS A
TRACK ROUGHLY 10NM WEST OF OKINAWA. AFTER TAU 48, THE MODELS BEGIN
TO DIVERGE, MOST SIGNIFICANTLY IN THE ALONG-TRACK DIRECTION.
CROSS-TRACK SPREAD INCREASES TO 90NM BY TAU 48, BETWEEN THE GALWEM
ON THE WEST SIDE OF THE ENVELOPE AND GFS AND NAVGEM ON THE EAST
SIDE. ALONG-TRACK SPREAD INCREASES TO 125NM BETWEEN THE GFS (SLOW)
AND EC-AIFS (FAST). UNCERTAINTY IN BOTH DIRECTIONS REACHES ITS
MAXIMUM AT TAU 72, AT 250NM IN BOTH ALONG- AND CROSS-TRACK ASPECTS.
THE MODELS CONVERGE SOMEWHAT BY THE END OF THE FORECAST, DECREASING
BOTH ASPECTS OF UNCERTAINTY. THE JTWC FORECAST IS PLACED NEAR THE
ECMWF AND GDM FNV3 MODEL THROUGH THE FORECAST PERIOD WITH HIGH
CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT, WITH ALL
MEMBERS OF THE CONSENSUS SUPPORTING A GRADUAL BUT STEADY WEAKENING
BEGINNING AT TAU 12, AND CONTINUING THROUGH THE END OF THE
FORECAST, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST. 

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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