WDPN31 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (MUN) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.1N 144.9E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 229 NM NORTHEAST OF CHICHI JIMA
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 04W HAS MAINTAINED ROBUST EASTWARD OUTFLOW, 
ENHANCED BY A JET AND TUTT CELL TO THE EAST. THE SYSTEM HAS DEVELOPED 
LIMITED OUTFLOW OVER THE CORE, WITH PERSISTENT DEEP CONVECTION 
OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). THE INITIAL 
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY, WHICH DEPICTS A COMPACT 
(APPROXIMATELY 70NM DIAMETER) CENTRAL DENSE OVERCAST FEATURE. A
040327Z AMSR2 89GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS TIGHTLY
WRAPPED LOW-LEVEL BANDING WRAPPING INTO A DEFINED LLCC. HOWEVER,
DEEP CONVECTIVE BANDING IS CONFINED TO THE EASTERN QUADRANT. THE
INITIAL INTENSITY IS DIFFICULT TO ASCERTAIN DUE TO THE COMPACT
NATURE OF THE SYSTEM AND WEAK DEEP CONVECTIVE STRUCTURE. CIMSS
OBJECTIVE ESTIMATES RANGE FROM 37 TO 54 KNOTS. SUBJECTIVE DVORAK
CURRENT INTENSITY ESTIMATES RANGE WIDELY FROM 35 TO 55 KNOTS.
RECENT ASCAT DATA INDICATES 35-40 KNOTS WHILE A 032024Z RCM-3 SAR
IMAGE SHOWED A VMAX OF 68 KNOTS. THE INITIAL INTENSITY IS HELD AT
55 KNOTS, WHICH IS CONSISTENT WITH THE TIGHTLY WRAPPED LOW-LEVEL
STRUCTURE AND THE HIGH END OF SUBJECTIVE AND OBJECTIVE INTENSITY
ESTIMATES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE EAST AND SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 49 KTS AT 040304Z
   CIMSS ADT: 37 KTS AT 040530Z
   CIMSS AIDT: 54 KTS AT 040530Z
   CIMSS D-MINT: 42 KTS AT 040330Z
   CIMSS D-PRINT: 42 KTS AT 040530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG EASTWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 04W IS EMBEDDED WITHIN A REVERSE TROUGH
FORMATION, WITH THE SUBTROPICAL STEERING RIDGE EXTENDING FROM THE
PHILIPPINES NORTHEASTWARD TO THE EASTERN PERIPHERY OF THE SYSTEM.
THIS IS GENERAL STEERING PATTERN WILL STEER THE SYSTEM NORTHEASTWARD 
THROUGH TAU 36 TOWARD A BREAK IN THE STR ASSOCIATED WITH AN UPPER-
LEVEL SHORTWAVE TROUGH. MODEST INTENSIFICATION IS EXPECTED DUE TO 
MARGINAL SST VALUES (24-25C) AND ROBUST OUTFLOW, WITH A PEAK INTENSITY
OF 70 KNOTS EXPECTED BY TAU 36. AFTER TAU 36, THE TROUGH WILL
PROPAGATE EASTWARD AND THE STR WILL REBUILD TO THE NORTH, WHICH
WILL RESULT IN A MORE NORTHWARD TRACK THROUGH TAU 96. AFTER TAU 96,
THE SYSTEM WILL ROUND THE STR AXIS AND ENCOUNTER SUBTROPICAL
WESTERLIES. RAPID WEAKENING WILL OCCUR THROUGH THE REMAINDER OF THE 
PERIOD DUE TO COLD SST VALUES AND HIGH (25-40 KNOTS) VERTICAL WIND 
SHEAR.    

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 48 BUT DIVERGES QUICKLY THROUGH TAU 120. HOWEVER, THE
DETERMINISTIC MODELS HAVE COME INTO BETTER AGREEMENT, WITH GFS NOW
SHIFTING SIGNIFICANTLY CLOSER TO THE BULK OF THE GUIDANCE. THE
040000Z GEFS ENSEMBLE CONTINUES TO INDICATE A WIDE SPREAD OF
SOLUTIONS, WITH THE BULK OF THE GUIDANCE WELL EAST OF JAPAN. THE
ECENS ENSEMBLE REMAINS IN TIGHTER AGREEMENT AND SUPPORTS THE JTWC
TRACK FORECAST WITH MEDIUM OVERALL CONFIDENCE. RELIABLE INTENSITY
GUIDANCE INDICATES A PEAK INTENSITY NEAR TAU 36 BUT VARIES
SIGNIFICANTLY FROM 62 TO 86 KNOTS. THIS REFLECTS THE UNCERTAINTY IN
THE JTWC INTENSITY FORECAST, WITH MEDIUM OVERALL CONFIDENCE.     

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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