WDPN31 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (JANGMI) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.0N 135.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 247 NM NORTH-NORTHWEST OF YAP
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SLOWLY BUT
CONTINUOUSLY ORGANIZING TROPICAL DEPRESSION (TD) 06W (JANGMI). THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE
VISIBLE SATELLITE IMAGERY DEPICTING A PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC). THE CORE OF THE VORTEX REMAINS BROAD,
BUT A 280321Z OCEANSAT-3 OSCAT PASS REVEALS SOME CONSOLIDATION
DEPICTED BY A MORE SYMMETRICAL WIND FIELD. THE SYSTEM HAS SLOWED DOWN, 
WHILE THE STEERING RIDGE TO THE EAST IS STILL BUILDING. THE INITIAL 
INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 
COMBINATION OF DVORAK AGENCY ESTIMATES AND OBJECTIVE AIDS LISTED 
BELOW, AS WELL AS THE AFOREMENTIONED OSCAT PASS SHOWING MAINLY 25-30 
KTS WIND SPEEDS. ENVIRONMENTAL ANALYSIS REVEALS CONDITIONS CONDUCIVE 
TO DEVELOPMENT, WITH LOW (5-10 KTS) VERTICAL WIND SHEAR (VWS), WARM 
(29-30 C) SEA SURFACE TEMPERATURES (SST) WITH HIGH OCEAN HEAT CONTENT, 
GOOD EQUATORWARD AND POLEWARD OUTFLOW, AND HIGH TROPOSPHERIC MOISTURE 
CONTENT.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: WEAK SUBTROPICAL RIDGING CENTERED TO
THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 36 KTS AT 280442Z
   CIMSS ADT: 32 KTS AT 280530Z
   CIMSS AIDT: 35 KTS AT 280530Z
   CIMSS D-MINT: 31 KTS AT 280444Z
   CIMSS D-PRINT: 34 KTS AT 280640Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 06W IS FORECAST TO TRACK NORTH-NORTHWESTWARD 
UNDER THE INFLUENCE OF A WEAK SUBTROPICAL RIDGE (STR) CENTERED TO THE 
EAST. AS THE SYSTEM APPROACHES THE AXIS OF THE RIDGE, IT WILL CONTINUE 
TO CONSOLIDATE AND INTENSIFY. SIMULTANEOUSLY, THE STR IS EXPECTED TO 
BUILD AND ASSERT ITSELF AS THE PRIMARY STEERING MECHANISM, RESULTING 
IN TD JANGMI TURNING NORTHWARD AROUND TAU 96. JUST BEFORE THAT, A PEAK 
INTENSITY OF 95 KTS IS FORECAST TO OCCUR AROUND TAU 72. AFTERWARDS, 
THE SYSTEM WILL TURN EASTWARD AND POLEWARD, WHILE WEAKENING, DUE TO 
RAPIDLY COOLING SSTS AND SLIGHTLY INCREASING WIND SHEAR. AS THE SYSTEM 
APPROACHES KADENA, LOWER OHC WILL RESULT IN A HIGHER PROBABILITY OF 
UPWELLING AND THEREFORE AN INCREASED RATE OF WEAKENING. TOWARDS THE 
END OF THE CURRENT FORECAST PERIOD, POLEWARD OUTFLOW IS EXPECTED TO 
DRASTICALLY INCREASE, BUT ITS POSITIVE EFFECTS WILL BE OFFSET BY SSTS 
DROPPING TO AS LOW AS 24-25 C BY TAU 120, AS THE SYSTEM APPROACHES 
KYUSHU, JAPAN.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN FAIR AGREEMENT, 
WITH ALL AVAILABLE TRACKERS DEPICTING A RECURVATURE SCENARIO DRIVEN BY 
THE STR TO THE EAST. THE TRACK FORECAST IS, HOWEVER, ASSESSED WITH 
MEDIUM CONFIDENCE DUE TO THE CONSENSUS ENVELOPE CROSS-TRACK SPREAD OF 
250 NM BETWEEN TAU 96 AND TAU 120, NEAR CPA TO KADENA, JAPAN. NAVGEM 
REMAINS THE PRIMARY OUTLIER OFFERING A SOLUTION DEPICTING A TRACK WEST 
OF THE CONSENSUS. THE REMAINDER OF THE MODELS FORM A TIGHTER GROUPING 
(130 NM CROSS-TRACK SPREAD), ALIGNING WITH ALL OF THE AVAILABLE 
EXPERIMENTAL AI GUIDANCE. THE JTWC TRACK FORECAST IS THEREFORE LAID 
SLIGHTLY TO THE EAST OF THE MULTI-MODEL CONSENSUS. IN REGARD TO 
INTENSITY, THE OFFICIAL JTWC FORECAST IS ALSO ASSESSED WITH MEDIUM 
CONFIDENCE. ALL AVAILABLE GUIDANCE FOLLOWS SIMILAR TIMELINES DEPICTING 
INTENSIFICATION THROUGH TAU 72, FOLLOWED BY STEADY WEAKENING. 
CONFIDENCE IS REDUCED PRIMARILY DUE TO A LARGE SPREAD NEAR THE PEAK. 
THE MOST AGGRESSIVE GUIDANCE COMES FROM THE GFS-DRIVEN COAMPS-TC, 
SHOWING A PEAK OF 105-110 KTS, WHILE THE STATISTICAL-DYNAMICAL MODELS 
PREDICT A WIND SPEED MAXIMUM OF 55-65 KTS. OF NOTE, HAFS IS CURRENTLY 
FAIRLY CONSERVATIVE WITH A PEAK OF 65-70 KTS. THE JTWC FORECAST IS 
LAID SLIGHTLY ABOVE THE MULTI-MODEL CONSENSUS, LEANING TOWARDS THE 
GROUPING OF THE MAJORITY OF THE MEMBERS. 

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