Advisories

WDPN31 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (DUJUAN) WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.7N 139.8E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 96 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY) 
24W 
(DUJUAN) UNDERGOING A PRONOUNCED RECONSOLIDATION PHASE, CHARACTERIZED 
BY SPIRAL BANDS OF DEEP CONVECTION WRAPPING TIGHTLY INTO A LOW-LEVEL 
CIRCULATION CENTER (LLCC) FULLY OBSCURED BY A ROBUST CENTRAL DENSE 
OVERCAST (CDO). THIS BRIEF STRENGTHENING TIMEFRAME IS DRIVEN 
PRIMARILY BY A VERY STRONG POLEWARD OUTFLOW CHANNEL, SUPPORTED BY 
CONDUCIVE SEA SURFACE TEMPERATURES (SST) OF 27-28 C, AND INCREASING 
BUT STILL LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS). THE 
SYSTEM HAS BEEN ABLE TO TRANSIENTLY COCOON ITSELF FROM THE 
SURROUNDING DRY-AIR ADVECTION ENTRAINING INTO THE INNER VORTEX CORE. 
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A FUSION 
OF RADAR IMAGERY AND A 210556Z F18 SSMIS 91 GHZ MICROWAVE PASS. THE 
INITIAL INTENSITY OF 70 KTS IS ALSO ASSESSED WITH HIGH CONFIDENCE, 
SUPPORTED BY OBSERVED CONVECTIVE CONSOLIDATION, INCREASED DVORAK 
AGENCY ESTIMATES, AND THE AUTOMATED OBJECTIVE AIDS LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND A 210051Z
METOP-C ASCAT

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.5 - 77 KTS
   CIMSS SATCON: 63 KTS AT 210422Z
   CIMSS ADT: 55 KTS AT 210530Z
   CIMSS AIDT: 54 KTS AT 210530Z
   CIMSS D-MINT: 71 KTS AT 210422Z
   CIMSS D-PRINT: 82 KTS AT 210630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 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 ACCELERATE ALONG A 
NORTHEASTWARD TRANSLATION VECTOR OVER THE NEXT 12 HOURS AND MAINTAIN 
THIS TRACK THROUGHOUT THE PREDICTION TIMEFRAME, COMMITTED TO THE 
NORTHWESTERN FLANK OF THE SUBTROPICAL RIDGE ANCHORED TO THE EAST. THE 
CLOSEST POINT OF APPROACH (CPA) TO YOKOSUKA, JAPAN IS ESTIMATED AT 81 
NM AND EXPECTED TO OCCUR WITHIN THE NEXT 6 HOURS. DURING THIS TIME, 
MODEST DEEPENING TO A PEAK INTENSITY OF 75 KTS IS PROJECTED UNDER A 
MARGINALLY CONDUCIVE THERMODYNAMIC AND SYNOPTIC ENVIRONMENT. THIS 
TRANSIENT STRENGTHENING PHASE IS SUPPORTED BY TY 24W BRIEFLY 
SHIELDING ITSELF FROM HOSTILE DRY-AIR ENTRAINMENT WHILST TAPPING INTO 
VERY STRONG POLEWARD OUTFLOW. SUBSEQUENT TO CPA PASSAGE AT YOKOSUKA, 
THE VORTEX IS FORECAST TO TRACK DIRECTLY ACROSS THE THERMALLY 
CONDUCIVE TAIL END OF THE KUROSHIO CURRENT (28-29 C) SHORTLY AFTER 
TAU 12. HOWEVER, THE ONSET OF EXTRATROPICAL TRANSITION (ETT) WILL 
INITIATE AS THERMODYNAMIC CONDITIONS DEGRADE OVER RAPIDLY COOLING SEA 
SURFACE TEMPERATURES, COUPLED WITH RELENTLESS DRY AIR ADVECTION AND 
DESTRUCTIVE VERTICAL WIND SHEAR REACHING 40+ KTS BY TAU 36. UPON 
INTERACTING WITH THE STRONG BAROCLINIC REGIME AND THE UPPER-LEVEL 
MID-LATITUDE WESTERLIES, TY DUJUAN WILL COMPLETE ETT BY THE END OF 
THE FORECAST TIMEFRAME.

MODEL DISCUSSION: HIGH CONFIDENCE ANCHORS THE OFFICIAL JTWC TRACK 
FORECAST, POSITIONED CLOSE TO THE MULTI-MODEL DYNAMICAL CONSENSUS IN 
LIGHT OF EXCELLENT NUMERICAL MODEL AGREEMENT. ALL MAJOR PREDICTION 
TRACKERS RESOLVE AN EXTREMELY TIGHT (5 NM) CROSS-TRACK DISPERSION 
ENVELOPE AT THE CPA TO YOKOSUKA. ALONG-TRACK SPREAD INCREASES TO 150 
NM BY TAU 36 AS THE SYSTEM COMPLETES ITS ETT. REGARDING INTENSITY 
OUTLOOKS, HAFS AND COAMPS-TC CONTRAST STATISTICAL-DYNAMICAL SCENARIOS 
PROGNOSTICATING MONOTONIC CYCLOLYSIS BY DEPICTING A MINOR RE-
DEEPENING TREND OVER THE NEXT 12 HOURS TOWARD A PEAK WIND SPEED 
PREDICTION OF 75-80 KTS. AFTER THAT, ALL AVAILABLE GUIDANCE PROJECTS 
RAPID WEAKENING AS THE SYSTEM ENTERS THE HOSTILE BAROCLINIC ZONE. THE 
OFFICIAL JTWC INTENSITY FORECAST CONVERGES NARROWLY NEAR THE 
DYNAMICAL CONSENSUS WITH HIGH CONFIDENCE.

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