WDPN31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (SIX) WARNING 
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.1N 141.0E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 24 NM NORTHWEST OF IWO TO, JAPAN
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A
CONSOLIDATING SYSTEM THAT FORMED ALONG THE OUTER EASTERN RIM OF A
MONSOON GYRE. FORMATIVE BANDS, MOSTLY FROM THE SOUTHERN
PERIPHERIES, ARE FEEDING INTO THE LOW LEVEL CIRCULATION CENTER
(LLCC) THAT IS OBSCURED BY AN ELONGATED CENTRAL DENSE OVERCAST
STRIATED ALONG THE NORTHERN EDGES BY STRONG SOUTHWESTERLY WINDS
ASSOCIATED WITH A MID-LATITUDE LOW TO THE NORTH ANCHORED JUST EAST
OF JAPAN. THE SAME STRONG UPPER LEVEL WINDS ARE PROVIDING EXCELLENT
POLEWARD VENTILATION TO THE SYSTEM. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON A DEFINED MICROWAVE LLCC FEATURE IN
THE 062041Z SSMIS IMAGE SUITE. THE INITIAL INTENSITY OF 25KTS IS
PLACED WITH MEDIUM CONFIDENCE BASED ON AN OVERALL ASSESSMENT OF
AGENCY AND OBJECTIVE DVORAK ESTIMATES AND IS CONSISTENT WITH THE
IMPROVED 6-HR CONVECTIVE STRUCTURE. ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT WITH WARM SST, MODERATE VWS, AND STRONG POLEWARD
OUTFLOW.

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

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE TO THE SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS DPRINT: 31 KTS AT 070000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TD 06W IS EXPECTED TO TRACK MORE POLEWARD
AFTER TAU 12 AS THE SUBTROPICAL RIDGE (STR) TO THE EAST ASSUMES
STEERING. AFTER TAU 96, IT WILL TURN NORTHEASTWARD AS IT CRESTS AND
ROUNDS THE STR AXIS, THE FAVORABLE CONDITIONS WILL FUEL A GRADUAL
INTENSIFICATION TO A PEAK OF 55KTS BY TAU 72 ON ITS CLOSEST LINE OF
APPROACH TO YOKOSUKA, JAPAN, APPROXIMATELY 285NM TO THE WEST.
AFTERWARD, INCREASING VWS, COOLING SST, AND DRY AIR INTRUSION WILL
BEGIN TO RAPIDLY ERODE THE SYSTEM. BY TAU 120, TD 06W WILL BE
REDUCED TO 30KTS AS IT APPROACHES THE BAROCLINIC ZONE. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT FOR
A FIRST WARNING, GRADUALLY AND EVENLY SPREADING OUT TO A MERE 155NM
BY TAU 72. AFTERWARD, THE MAIN PACK SPREADS OUT TO 160NM WITH
NOTABLE ALONG-TRACK VARIANCES, HOWEVER. GFS IS THE SOLE
LEFT-OF-TRACK OUTLIER AFTER TAU 72, SIGNIFICANTLY DEVIATING FROM
THE MAIN PACK BY 45 DEGREES TOWARD MISAWA. IN VIEW OF THESE, AND
GIVEN THE FORMATIVE NATURE OF THE SYSTEM, THERE IS MEDIUM
CONFIDENCE IN THE JTWC TRACK FORECAST UP TO TAU 72, THEN LOW
CONFIDENCE AFTERWARD.

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