WDPN32 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (MAN-YI) WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.0N 127.8E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 427 NM EAST-SOUTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON
25W (MAN-YI) WITH A WELL-DEFINED EYE AND SYMMETRIC CENTRAL DENSE
OVERCAST OVER THE EYEWALL. CLOUD TOPS WITHIN THE EYEWALL CONTINUE
TO COOL, SUGGESTING CONTINUED INTENSIFICATION. ENVIRONMENTAL
ANALYSIS INDICATES THAT 25W IS IN A HIGHLY FAVORABLE ENVIRONMENT
CHARACTERIZED BY STRONG RADIAL OUTFLOW ALOFT, LOW (5-10 KTS)
VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
EYE IN THE ANIMATED EIR IMAGERY. THE INITIAL INTENSITY OF 110 KTS
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND
OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE
NORTH-NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS DPRINT: 110 KTS AT 151800Z
   CIMSS DMINT: 104 TKS AT 151800Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 25W IS FORECAST TO CONTINUE TRACKING
WEST-NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE STR
THROUGH TAU 36 AS IT APPROACHES LUZON. LANDFALL IS EXPECTED TO
OCCUR RIGHT AROUND TAU 36 ABOUT 60 NM SOUTHWEST OF CASIGURAN. AFTER
THE VORTEX EMERGES WITHIN THE SOUTH CHINA SEA, RIDGING EXTENDING
WESTWARD AND NORTH OF THE SYSTEM WILL CONTINUE TO DRIVE 25W FURTHER
WESTWARD. ADDITIONALLY, AN INCOMING COLD SURGE WILL PREVENT THE
SYSTEM FROM GAINING LATITUDE. REGARDING INTENSITY, 25W IS FORECAST
TO CONTINUE INTENSIFYING OVER THE NEXT 12 HOURS TO A PEAK OF 115
KTS, AND POSSIBLY HIGHER. AROUND TAU 24, THE VORTEX WILL BEGIN TO
INTERACT WITH THE TERRAIN OF THE PHILIPPINES WHICH WILL INITIATE A
SLIGHT WEAKENING TREND AS IT APPROACHES THE COAST OF LUZON. 25W IS
THEN FORECAST TO DROP TO BORDERLINE TYPHOON STRENGTH AS IT ENTERS
THE SOUTH CHINA SEA. INCREASING VERTICAL WIND SHEAR AND DRY AIR
ENTRAINMENT, AIDED BY THE COLD SURGE, WILL CAUSE 25W TO STEADILY
WEAKEN THROUGH TAU 96. AFTER TAU 96, THE ENVIRONMENT QUICKLY
WORSENS FURTHER WITH SHEAR INCREASING UPWARDS OF 30 KTS AND VAST
AMOUNTS OF DRY AIR ENTRAINMENT. AS A RESULT, THE SYSTEM IS EXPECTED
TO DISSIPATE AROUND THE END OF THE FORECAST PERIOD SOUTH OF HINAN.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN VERY GOOD
AGREEMENT REGARDING THE TRACK OF 25W THROUGHOUT THE FORECAST. A
CROSS-TRACK SPREAD OF 25 NM AT THE TIME OF LANDFALL IN LUZON, NEAR
TAU 36, OPENS UP TO JUST 175 NM AT TAU 120. THE JTWC TRACK FORECAST
IS PLACED CLOSE TO CONSENSUS THROUGH THE FORECAST PERIOD WITH
OVERALL HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN WORSE AGREEMENT
WITH A LARGE DIFFERENCE BETWEEN HAFS-A AND COAMPS-TC (FIRST GROUP) 
AND HWRF AND GFS (SECOND GROUP). THE FIRST GROUP CONTINUES 
INTENSIFICATION TO 115 KTS AT TAU 12 AND WEAKENING THEREAFTER WHILE 
THE SECOND GROUP SUGGESTS WEAKENING THROUGHOUT THE ENTIRE FORECAST 
PERIOD. THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE FIRST 
GROUP DUE TO THE FAVORABLE ENVIRONMENT WITH OVERALL MEDIUM 
CONFIDENCE. 

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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