WDPN31 PGTW 090300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (LAN) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.2N 146.9E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 308 NM EAST OF IWO TO
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM
CONTINUED TO CONSOLIDATE AS CENTRAL CONVECTION DEEPENED AND WRAPPED
TIGHTER INTO AN OBSCURED LOW LEVEL CIRCULATION (LLC) WITH A PARTIAL
PINHOLE FORMATIVE EYE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE FORMATIVE EYE THAT LINED UP PERFECTLY WITH
A 082338Z ASCAT BULLSEYE PASS. THE INITIAL INTENSITY IS ALSO PLACED
WITH HIGH CONFIDENCE BASED ON THE HIGH END OF AGENCY AND AUTOMATED
DVORAK ESTIMATES AND THE ASCAT PASS THAT REFLECTS THE 6-HR
IMPROVEMENT. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH WARM
SST, LOW VWS, AND EFFICIENT DUAL OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST. 


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 46 KTS AT 081945Z
   CIMSS ADT: 41 KTS AT 082340Z
   CIMSS D-PRINT: 54 KTS AT 090100Z


FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG EQUATORWARD
   OTHER FACTORS: STRONG EASTWARD OUTFLOW INTO A TUTT CELL. 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS LAN WILL CONTINUE ON A MORE NORTHWESTWARD
TRACK UNDER THE STEERING STR TOWARD YOKOSUKA, JAPAN, AS THE STR
RECEDES WITH THE APPROACH OF A MID-LATITUDE TROUGH FROM THE
NORTHWEST. THE FAVORABLE ENVIRONMENT WILL FUEL A STEADY
INTENSIFICATION TO A PEAK OF 90KTS AT TAUS 36-48. AFTERWARD,
COOLING SST DUE TO UPWELLING IN RELATIVELY SHALLOW WATERS WILL
SLIGHTLY AND GRADUALLY WEAKEN THE SYSTEM, DOWN TO 80KTS BY TAU 120
AS IT APPROACHES SAGAMI BAY.


MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH A
GRADUAL AND EVEN SPREAD TO A MERE 140NM BY TAU 120, LENDING HIGH
CONFIDENCE TO THE JTWC TRACK FORECAST. GIVEN THE VARIABILITY OF
INTENSITY CHANGE DUE TO UPWELLING, THERE IS ONLY MEDIUM CONFIDENCE
IN THE JTWC INTENSITY FORECAST.


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