WDPN32 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (NORU) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.1N 121.4E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 38 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM 
HAS MADE LANDFALL OVER AURORA PROVINCE, PHILIPPINES AND IS NOW 
TRACKING INLAND INTO CENTRAL LUZON. THE SYSTEM NOTICEABLY WEAKENED AS 
EVIDENCED BY THE DISSOLUTION OF THE EYE AND THE UNRAVELING OF THE 
EYEWALL. CONVECTIVE TOPS HAVE ALSO WARMED UP. THE INITIAL POSITION 
WAS EXTRAPOLATED FROM THE EYE FEATURE BEFORE IT CLOSED PRIOR TO 
LANDFALL. THE INITIAL INTENSITY WAS BASED ON THE HIGH END OF AGENCY 
AND AUTOMATED DVORAK ESTIMATES AND PROPORTIONAL TO THE DECAY WHILE 
REPRESENTING A STILL VERY INTENSE TYPHOON.

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

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


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T6.5 - 127 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG RADIAL

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

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 ACROSS THE PLAINS OF CENTRAL LUZON THEN OVER THE ZAMBALES 
MOUNTAIN RANGE BEFORE EXITING INTO THE SOUTH CHINA SEA (SCS) JUST 
AFTER TAU 06. THE LAND INTERACTION, ESPECIALLY WITH THE MOUNTAIN 
RANGE WILL SIGNIFICANTLY ERODE THE SYSTEM DOWN TO 70 KTS 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. TY 18W WILL MAKE A FINAL LANDFALL SOUTH 
OF HUE AROUND TAU 66. 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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