WDPN32 PGTW 250900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 18W (NORU) WARNING NR 
014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.0N 122.5E
   INITIAL INTENSITY: 130 KTS
   GEOGRAPHIC REFERENCE: 90 NM EAST-NORTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A VERY INTENSE
MEDIUM-SIZED SUPER TYPHOON WITH A 6-NM PINHOLE EYE ABOUT TO MAKE
LANDFALL INTO CENTRAL LUZON, PHILIPPINES. THE SYSTEM HAS WEAKENED
SLIGHTLY AS THE WESTERN FEEDER BANDS HAVE MADE LANDFALL; HOWEVER,
THE TIGHT EYEWALL REMAINED SYMMETRICAL AND DEEP WITH OVERSHOOTING
COLD TOPS BELOW -80C. WITH RELATIVELY LOW VWS, THE EYE, WHERE THE
INITIAL POSITION IS BASED ON WITH HIGH CONFIDENCE, IS VERTICALLY
STACKED AS EVIDENCED BY VERY WARM 20C TEMPERATURE BEFORE IT SHRUNK
TO A PINHOLE SIZE. AGENCY AND AUTOMATED DVORAK ESTIMATES ARE
TRENDING DOWN BUT, OVERALL, SUPPORT THE INITIAL INTENSITY.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T6.0 - 115 KTS
   KNES: T7.0 - 140 KTS 
   CIMSS ADT: 119 KTS AT 250540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: STY NORU WILL CONTINUE TO TRACK GENERALLY
WESTWARD UNDER THE STR, MAKE LANDFALL OVER AURORA PROVINCE,
PHILIPPINES, BY TAU 06 AND TRACK ACROSS THE PLAINS OF CENTRAL LUZON
THEN OVER THE ZAMBALES MOUNTAIN RANGE BEFORE EXITING INTO THE SOUTH
CHINA SEA (SCS) JUST AFTER TAU 12. THE LAND INTERACTION, ESPECIALLY
WITH THE MOUNTAIN RANGE WILL SIGNIFICANTLY ERODE THE SYSTEM DOWN TO
85KTS BY TAU 12. AFTER IT EXITS INTO THE SCS, THE WARM WATERS WILL 
HELP FUEL A SECONDARY INTENSIFICATION TO A PEAK OF 100KTS BY TAU 48 
AS IT APPROACHES CENTRAL VIETNAM. STY 18W WILL MAKE A FINAL LANDFALL
SOUTH OF HUE AROUND TAU 60. AFTER LANDFALL, THE RUGGED TERRAIN OF
VIETNAM, CAMBODIA, AND THAILAND WILL RAPIDLY WEAKEN THE SYSTEM TO
DISSIPATION BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY TIGHT AGREEMENT WITH
NVGM THE SOLE RIGHT OF TRACK OUTLIER, LENDING HIGH CONFIDENCE IN
THE JTWC TRACK FORECAST, ADJUSTED SLIGHTLY LEFT OF CONSENSUS TO
OFFSET NVGM, UP TO TAU 72, THEN LOW CONFIDENCE AFTERWARD DUE TO THE
UNCERTAINTY OF PROLONGED LAND INTERACTION. THERE IS ALSO MEDIUM AND
LOW CONFIDENCE IN THE INTENSITY FORECAST FOR THE SAME REASON. 

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