WDPN31 PGTW 070900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.1N 115.2E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 91 NM SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS
SLOWED DOWN AND MAINTAINED A COMPACT CENTRAL DENSE OVERCAST AND A
SHARPLY-OUTLINED 8-NM PINHOLE EYE EVEN AS THE EYEWALL CONVECTIVE
TOPS HAVE SLIGHTLY WARMED AND FEEDER BANDS LOOSENED A BIT. A
070229Z ASCAT BULLSEYE PASS AND NUMEROUS NEARBY SURFACE
OBSERVATIONS, INCLUDING THOSE IN THE HONG KONG AREA, CONFIRMED A
MORE COMPACT WIND RADII THAN PREVIOUSLY ANALYZED. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PINHOLE EYE IN
THE MSI LOOP THAT IS CONCENTRIC WITH A DEFINED EYE FEATURE IN A
COMPOSITE RADAR LOOP. THE INITIAL INTENSITY IS ALSO ASSESSED WITH
HIGH CONFIDENCE BASED ON OVERALL ASSESSMENT OF AGENCY AND AUTOMATED
DVORAK ESTIMATES AND REFLECTS THE SLIGHT WEAKENING OVER THE LAST
SIX HOURS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: DEEP LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTHWEST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   DEMS: T6.0 - 115 KTS
   CIMSS SATCON: 87 KTS AT 070533Z
   CIMSS ADT: 87 KTS AT 070530Z

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

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: TYPHOON KOINU WILL CONTINUE GENERALLY
WEST-SOUTHWESTWARD UNDER THE STEERING STR. THE MARGINALLY FAVORABLE
ENVIRONMENT WILL PROMOTE A SLOW WEAKENING TO 80KTS BY TAU 48.
AFTERWARD, DRY AIR INTRUSION FROM MAINLAND CHINA PLUS LANDFALL INTO
HAINAN BY TAU 72, SPLASH BACK INTO THE GULF OF TONKIN, THEN FINAL
LANDFALL INTO CENTRAL VIETNAM, WILL ERODE THE SYSTEM AT A FASTER
RATE TO 25KTS, POSSIBLY DISSIPATED, BY TAU 120 AS IT CROSSES INTO 
CAMBODIA.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH AN EVEN SPREAD TO 160NM BY TAU 72, THEN MORE ERRATICALLY TO
348NM BY TAU 120, LENDING MEDIUM CONFIDENCE TO THE JTWC TRACK AND
INTENSITY 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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