WDPN32 PGTW 261500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (NORU) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.9N 115.7E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 317 NM WEST-NORTHWEST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE
SYSTEM MAINTAINED DEEP CONVECTIVE SIGNATURE AND A SMALL EYE THAT HAS
BECOME PARTLY CLOUD-FILLED. CURVED BANDS FEEDING IN FROM THE WEST
AND SOUTH HAVE BECOME MORE COMPACT. THE INITIAL POSITION WAS BASED
ON THE EYE FEATURE IN A LOW VWS ENVIRONMENT, HENCE NO ADJUSTMENT
FOR TILT. THE INITIAL INTENSITY WAS BASED ON THE HIGH END OF AGENCY 
AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SUSTAINED 6-HR 
CONVECTIVE STRUCTURE.

INITIAL WIND RADII BASIS: PERSISTENCE. 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE TO THE
NORTH.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T4.0 - 65 KTS
   CIMSS ADT: 79 KTS AT 261140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY NORU WILL CONTINUE TO TRACK GENERALLY
WESTWARD IN THE SOUTH CHINA SEA WHERE THE WARM WATERS, COMBINED
WITH STRONG RADIAL OUTFLOW AND LOW VWS, WILL HELP FUEL A SECONDARY
INTENSIFICATION TO A PEAK OF 110KTS BY TAU 24 AS IT APPROACHES
CENTRAL VIETNAM. AFTER TAU 24, INCREASING VWS WILL BEGIN TO WEAKEN
THE SYSTEM DOWN TO 95 KTS BY TAU 36. TY 18W WILL MAKE A FINAL
LANDFALL SOUTH OF HUE JUST AFTER TAU 36. THE RUGGED TERRAIN
OF VIETNAM, CAMBODIA, AND THAILAND WILL RAPIDLY WEAKEN THE SYSTEM
TO DISSIPATION BY TAU 72. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY TIGHT AGREEMENT WITH
NVGM THE SOLE RIGHT-OF-TRACK OUTLIER BEGINNING TAU 36, LENDING HIGH
CONFIDENCE IN THE JTWC TRACK FORECAST, ADJUSTED SLIGHTLY TO THE
LEFT OF CONSENSUS TO OFFSET NVGM. THERE IS ONLY MEDIUM CONFIDENCE IN 
THE INTENSITY FORECAST DUE TO THE UNCERTAINTY OF LAND INTERACTION 
AFTER TAU 36.


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