Advisories

WDPN31 PGTW 211500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (DUJUAN) WARNING NR 025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 34.9N 141.8E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 106 NM SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 20 KTS
   SIGNIFICANT WAVE HEIGHT: 34 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON 
(TY) 24W (DUJUAN) ACCELERATING RAPIDLY NORTHEASTWARD UNDER THE 
INFLUENCE OF A SUBTROPICAL RIDGE CENTERED TO THE EAST-SOUTHEAST. 
ENVIRONMENTAL CONDITIONS HAVE DEGRADED SINCE THE CLOSEST POINT OF 
APPROACH (CPA) TO MAINLAND JAPAN WITHIN THE LAST 6 HOURS, BUT AN 
EXTREMELY ROBUST POLEWARD OUTFLOW CHANNEL CAN STILL BE EASILY 
IDENTIFIED. LAND INTERACTION HAS DISRUPTED CONVECTIVE BANDING OVER THE 
NORTHWESTERN QUADRANT, AN EFFECT AMPLIFIED BY PERSISTENT DRY-AIR 
ADVECTION FROM THE WEST, WHILE SOUTHWESTERLY VERTICAL WIND SHEAR (VWS) 
REMAINS MODERATE TO HIGH AT 20-25 KTS. FOLLOWING A BRIEF PERIOD OF 
SLIGHTLY COOLER WATER INFLUENCE, THE VORTEX IS NOW LOCATED DIRECTLY 
OVER THE WARM (28-29 C) TAIL END OF THE KUROSHIO CURRENT, WHICH IS 
ASSISTING WITH MINOR RECONSOLIDATION. THE SYSTEM HAS LIKELY REACHED 
ITS PEAK INTENSITY OF 70-75 KTS WITHIN A MARGINALLY CONDUCIVE SYNOPTIC 
REGIME, NURTURED BY A STRONG POLEWARD EXHAUST PATHWAY AND TRANSIENT 
SHELTERING FROM HOSTILE ENTRAINMENT. THE INITIAL POSITION IS PLACED 
WITH HIGH CONFIDENCE BASED ON A 211209Z METOP-C ASCAT PASS, 
CORROBORATED BY THE RADAR IMAGERY LOOP AND A TIGHT GROUPING OF AGENCY 
FIXES. SIMILARLY, THE INITIAL INTENSITY OF 70 KTS IS ALSO ASSESSED 
WITH HIGH CONFIDENCE BASED ON DVORAK ESTIMATES AND THE AUTOMATED 
OBJECTIVE AIDS LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND A 211209Z
METOP-C ASCAT PASS

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE
EAST-SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.5 - 77 KTS
   CIMSS ADT: 57 KTS AT 211130Z
   CIMSS AIDT: 55 KTS AT 211130Z
   CIMSS D-MINT: 74 KTS AT 210811Z
   CIMSS D-PRINT: 77 KTS AT 211130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY DUJUAN IS FORECAST TO CONTINUE RAPIDLY 
PROPAGATING ALONG A NORTHEASTWARD TRANSLATION VECTOR FLANKING THE 
SUBTROPICAL RIDGE (STR) ANCHORED TO THE SOUTHEAST. TY DUJUAN IS 
CURRENTLY TRAVERSING THE THERMALLY CONDUCIVE TAIL END OF THE KUROSHIO 
CURRENT BEFORE TRANSITIONING OVER DRASTICALLY COLDER SEA SURFACE 
TEMPERATURE (SST) FIELDS. POST-TAU 12, THERMODYNAMIC SUSTAINABILITY 
COLLAPSES AS RELENTLESS DRY-AIR ADVECTION AND DESTRUCTIVE VWS 
EXCEEDING 30 KTS WILL SIGNAL THE ONSET OF EXTRATROPICAL TRANSITION 
(ETT). UPON CONFLUENCE WITH THE STRONG MID-LATITUDE BAROCLINIC ZONE 
AND A POWERFUL WESTERLY JET STREAM ALOFT, THE CYCLONE WILL COMPLETE 
ETT BY THE END OF THE CURRENT FORECAST TIMEFRAME.

MODEL DISCUSSION: NUMERICAL MODEL TRACK PREDICTIONS CONTINUE TO DEPICT 
GOOD COHERENCE, WITH DYNAMICAL TRACKERS CLUSTERING WITHIN A TIGHT 70 
NM CROSS-TRACK DISPERSION ENVELOPE AT TAU 36. ACCORDINGLY, THE 
OFFICIAL JTWC TRACK FORECAST IS POSITIONED WITH HIGH CONFIDENCE NEAR 
THE MULTI-MODEL CONSENSUS. REGARDING INTENSITY, ALL AVAILABLE GUIDANCE 
INDICATES PEAK INTENSITY HAS ALREADY OCCURRED, GIVING WAY TO RAPID 
WEAKENING INITIATING NEAR TAU 12. IN TANDEM WITH THE MULTI-MODEL 
CONSENSUS, THE OFFICIAL JTWC INTENSITY PROFILE IS DESIGNATED WITH HIGH 
CONFIDENCE.

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