WDPN31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (MUN) WARNING NR 
024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 36.7N 148.0E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 373 NM EAST OF NARITA AIRPORT
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS A FULLY EXPOSED
LOW-LEVEL CIRCULATION CENTER (LLCC) ASSOCIATED WITH TROPICAL
DEPRESSION (TD) 04W (MUN), ENCIRCLED BY FRAGMENTED, SHALLOW
CONVECTIVE BANDING. THE SYSTEM IS CURRENTLY ROUNDING THE AXIS OF A
STR LOCATED TO THE EAST AND THEREFORE BEGINNING TO TURN
NORTH-NORTHEASTWARD. DESPITE EXPERIENCING STRONG VERTICAL WIND
SHEAR (VWS) EXCEEDING 35 KTS AND BEING EMBEDDED IN AN INCREASINGLY
DRY ENVIRONMENT, THE SYSTEM CONTINUES TO MAINTAIN SHALLOW CORE
VORTEX STRUCTURE. ENVIRONMENTAL DIAGNOSTICS INDICATE A LIMITED
EQUATORWARD OUTFLOW CHANNEL AND COOLING (24-25 C) SEA SURFACE 
TEMPERATURES (SST). THE INITIAL POSITION IS DETERMINED WITH HIGH 
CONFIDENCE BASED ON THE CLEARLY DEFINED LLCC OBSERVED IN THE SATELLITE 
IMAGERY. INITIAL INTENSITY IS ESTIMATED AT 30 KTS WITH HIGH CONFIDENCE 
AS WELL, AND IS DERIVED FROM A COMPOSITE ASSESSMENT OF SUBJECTIVE 
DVORAK TECHNIQUE FIXES, OBJECTIVE INTENSITY ESTIMATES OUTLINED BELOW, 
AS WELL AS A 071030Z METOP-B AND METOP-C ASCAT PASSES.

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

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 39 KTS AT 070858Z
   CIMSS ADT: 25 KTS AT 071130Z
   CIMSS AIDT: 37 KTS AT 071130Z
   CIMSS D-MINT: 28 KTS AT 070710Z
   CIMSS D-PRINT: 27 KTS AT 071230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 30+ KTS
   SST: 24-25 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 04W IS EXPECTED TO BEGIN RAPIDLY
ACCELERATING AND CONTINUING ON WITH THE RECURVATURE PHASE ALONG THE
NORTHWESTERN PERIPHERY OF A STR TO THE EAST. CONCURRENTLY, IT IS 
FORECAST TO UNDERGO GRADUAL WEAKENING DUE TO ESCALATING ENVIRONMENTAL
HOSTILITY. INITIATION OF SUBTROPICAL TRANSITION IS ANTICIPATED BY
TAU 24 AND IS PROJECTED TO CONCLUDE BY TAU 36, MARKING THE TERMINUS
OF THE CURRENT FORECAST PERIOD. AT THAT TIME, THE SYSTEM IS
FORECAST TO DEGRADE TO A 25 KT SUBTROPICAL DEPRESSION AND BECOME
COMPLETELY EMBEDDED IN A DEEP-LAYER WESTERLY FLOW.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE EXHIBITS TIGHT INITIAL
CONSENSUS WITH A CROSS-TRACK SPREAD OF 40 NM AT TAU 12, GRADUALLY
INCREASING TO 160 NM BY THE END OF FORECAST PERIOD. BEYOND TAU 12,
TRACK SPREAD WIDENS DUE TO DIFFERING ASSESSMENT OF THE INTERACTION
WITH THE BAROCLINIC ZONE AND ASSOCIATED WESTERLY UPPER-LEVEL FLOW
REGIME. THE GFS DETERMINISTIC MODEL SUGGESTS A SHARPER AND MORE
RAPID TURN, WHEREAS THE ECMWF DETERMINISTIC AND ECMWF ENSEMBLE 
SOLUTIONS INDICATE A SLOWER AND MORE GRADUAL RECURVATURE, WHILE
SIMULTANEOUSLY DISSIPATING THE VORTEX BEYOND TAU 12. ACCORDINGLY,
THE JTWC FORECAST TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL
CONSENSUS AND IS ASSESSED WITH MEDIUM CONFIDENCE. INTENSITY
GUIDANCE EXHIBITS POOR AGREEMENT AS A RESULT OF BAROCLINIC FORCING
IMPACTS PICKED UP BY GFS AND HWRF, WHICH INDICATE POTENTIAL FOR
SLIGHT INTENSIFICATION. MEANWHILE COAMPS-TC AND HAFS SUGGEST IMMEDIATE 
WEAKENING AND EVENTUAL DISSIPATION.

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