Advisories

WDPN31 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (DUJUAN) WARNING NR 
021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.4N 137.6E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 312 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL 
STORM (TS) 24W (DUJUAN) STRUGGLING TO CONSOLIDATE ITS DEEP CONVECTION, 
AS A SIGNIFICANT AMOUNT OF DRY AIR IS BEING INJECTED INTO THE CORE OF 
THE VORTEX. THE SYSTEM MAINTAINS A TIGHT LOW-LEVEL CIRCULATION CENTER 
(LLCC), WHICH IS IDENTIFIED WITH HIGH CONFIDENCE UTILIZING SATELLITE 
IMAGERY AND EXTRAPOLATION FROM A 200855Z WSFM MWI 37 GHZ MICROWAVE 
PASS. INTENSITY IS ALSO ASSESSED WITH HIGH CONFIDENCE BASED ON A 
COHERENT FUSION OF SUBJECTIVE SATELLITE DVORAK FIXES AND AUTOMATED 
OBJECTIVE ESTIMATES LISTED BELOW. ASIDE FROM THE DRY AIR, OTHER 
ENVIRONMENTAL PARAMETERS REMAIN MOSTLY FAVORABLE FOR INTENSIFICATION. 
THE POLEWARD OUTFLOW CHANNEL REMAINS ROBUST, SEA SURFACE TEMPERATURES 
(SST) ARE WARM (28-29 C), AND VERTICAL WIND SHEAR (VWS) IS LOW (10-15 
KTS).

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND A PARTIAL
201205Z METOP-B ASCAT PASS

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   CIMSS ADT: 51 KTS AT 201130Z
   CIMSS AIDT: 48 KTS AT 201130Z
   CIMSS D-PRINT: 66 KTS AT 201230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 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: THE TRANSLATION VECTOR OF TS 24W IS EXPECTED TO 
CONTINUE TURNING TOWARD THE NORTHEAST WITHIN THE COMING 12 HOURS AND 
THROUGHOUT THE CURRENT FORECAST PERIOD, AS THE CYCLONE TRANSITS ALONG 
THE NORTHWESTERN PERIPHERY OF THE STR ANCHORED TO THE EAST. THE 
CLOSEST POINT OF APPROACH (CPA) TO YOKOSUKA, JAPAN, IS ESTIMATED AT 80 
NM, COINCIDING WITH THE TIMELINE JUST BEFORE TAU 24. BETWEEN TAUS 24 
AND 36, SLIGHT DYNAMIC DEEPENING TO A PEAK INTENSITY OF 70 KTS IS 
PROJECTED UNDER A MARGINALLY FAVORABLE ENVIRONMENT, AIDED BY THE 
CYCLONE TEMPORARILY COCOONING FROM HOSTILE DRY AIR WHILE PROPAGATING 
OVER THE TAIL END OF THE WARM KUROSHIO CURRENT AND HARNESSING ENHANCED 
POLEWARD OUTFLOW DYNAMICS. SHORTLY AFTER, HOWEVER, THE ONSET OF 
EXTRATROPICAL TRANSITION (ETT) WILL EMERGE AS WATERS SHARPLY COOL, 
HOSTILE DRY-AIR ENTRAINMENT INTENSIFIES, AND VERTICAL WIND SHEAR 
ACCELERATES TO 30+ KTS AROUND TAU 48. INTEGRATING RAPIDLY INTO THE 
MID-LATITUDE WESTERLIES, TS DUJUAN WILL COMPLETE THE TRANSITION PRIOR 
TO TAU 60.

MODEL DISCUSSION: IN TERMS OF TRACK OUTLOOK, EXCELLENT AGREEMENT 
ENVELOPS THE DYNAMICAL MODEL PREDICTIONS, DEPICTING A TIGHT 20 NM 
SPREAD AT THE CPA TO YOKOSUKA, BALANCED BY A MODERATE ALONG-TRACK 
TIMING VARIABILITY OF 80 NM. BASED ON THIS CONGRUENT GROUPING, THE 
OFFICIAL JTWC TRACK PROGNOSIS IS POSITIONED CLOSE TO THE MULTI-MODEL 
CONSENSUS WITH HIGH CONFIDENCE. REGARDING INTENSITY GUIDANCE, THE 
DYNAMICAL ENVELOPE PROJECTS A BRIEF STEADY-STATE RUN OVER THE COMING 
12 HOURS, TRANSITIONING TO SLIGHT INTENSIFICATION THEREAFTER, THOUGH 
THE INTENSITY PROJECTION UNCERTAINTY ENVELOPE WIDENS TO A 25 KTS 
SPREAD (SPREADING FROM 50 TO 75 KTS) BY TAU 36. WHILE STATISTICAL-
DYNAMICAL SCENARIOS PERSISTENTLY PROJECT STEADY WEAKENING, THE 
DYNAMICAL MODEL SOLUTIONS (HAFS, COAMPS-TC, AND GFS) RESOLVE A 
TRANSITIONAL INTENSIFICATION TREND PROGRESSING TO A PEAK INTENSITY OF 
65-70 KTS NEAR TAU 36. ALIGNED WITH THIS COHERENT TENDENCY, THE 
OFFICIAL JTWC INTENSITY FORECAST PARALLELS THE DYNAMICAL CONSENSUS 
WITH MEDIUM CONFIDENCE.

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