WDPN32 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (MAN-YI) WARNING NR 033//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.0N 122.9E
   INITIAL INTENSITY: 120 KTS
   GEOGRAPHIC REFERENCE: 113 NM EAST-NORTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 25W
(MAN-YI) WITH AN IMPROVED APPEARANCE AS OPPOSED TO 6 HOURS AGO. IN
PARTICULAR, THE EYE HAS BECOME MORE DEFINED AND THE OVERALL
SYMMETRY HAS ENHANCED. THE STRUCTURE HAS SEEMED TO RECOVER SINCE
THE PREVIOUS LANDFALL OVER CATANDUANES ISLAND. ENVIRONMENTAL
ANALYSIS INDICATES THAT 25W IS IN A FAVORABLE ENVIRONMENT
CHARACTERIZED BY STRONG RADIAL OUTFLOW ALOFT, LOW (5-10 KTS)
VERTICAL WIND SHEAR, AND WARM (28-29 C) SEA SURFACE TEMPERATURES.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
DEFINED EYE IN THE ANIMATED MSI. THE INITIAL INTENSITY OF 120 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-LAYER
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T7.0 - 140 KTS 
   RCTP: T6.5 - 127 KTS
   KNES: T6.0 - 115 KTS
   CIMSS SATCON: 130 KTS AT 170000Z
   CIMSS ADT: 117 KTS AT 170000Z
   CIMSS AIDT: 113 KTS AT 170000Z
   CIMSS DPRINT: 113 KTS AT 170000Z
   CIMSS DMINT: 119 KTS AT 162218Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG RADIAL

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

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
NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE STR OVER THE
NEXT 12 HOURS WITH LANDFALL EXPECTED TO OCCUR AROUND TAU 6 NEAR
BALER AND DIPACULAO. NEAR TAU 12, THE SYSTEM WILL HAVE MADE ITS WAY
ACROSS LUZON AND WILL APPROACH THE SOUTH CHINA SEA. AS 25W ENTERS
THE SOUTH CHINA SEA, RIDGING EXTENDING WESTWARD OVER SOUTHERN CHINA
WILL TAKE OVER AS THE PRIMARY STEERING MECHANISM AND WILL DRIVE THE
SYSTEM FURTHER NORTHWESTWARD THROUGH TAU 36. AROUND TAU 36, A
STRONG COLD SURGE FLOWING SOUTHWESTWARD NEAR TAIWAN WILL PREVENT
THE SYSTEM FROM GAINING ANY FURTHER LATITUDE. 25W IS THEN FORECAST
TO TRACK WESTWARD TO WEST-SOUTHWESTWARD THROUGH TAU 72. AFTER TAU
72, THE WEAKENED VORTEX WILL TURN MORE SOUTHWESTWARD AS IT TRACKS
ALONG THE LOW-LEVEL STEERING PATTERN AS IT DISSIPATES. REGARDING
INTENSITY, 25W IS FORECAST TO MAINTAIN INTENSITY UP UNTIL LANDFALL
WITH RAPID WEAKENING AFTERWARDS AS IT TRACKS ACROSS LUZON. A
BORDERLINE TYPHOON IS EXPECTED TO EMERGE WITHIN THE SOUTH CHINA
SEA. AS THE SYSTEM TRAVERSES ACROSS THE SOUTH CHINA SEA, THE
ENVIRONMENT IS EXPECTED TO BE MARGINAL DUE TO INCREASING VERTICAL
WIND SHEAR AND COLD, DRY AIR BEING BROUGHT IN FROM THE COLD SURGE.
AS A RESULT, 25W IS FORECAST TO WEAKEN TO AROUND 50 KTS AT TAU 48.
AFTER TAU 48, THE ENVIRONMENT WILL QUICKLY WORSEN FURTHER DUE TO
SHEAR INCREASING TO 30 KTS AT TAU 48 AND 40 KTS AT TAU 72.
ADDITIONALLY, DRY AIR WILL QUICKLY BEGIN TO ENTRAIN INTO THE CORE
OF THE VORTEX. THIS WILL CAUSE THE SYSTEM TO RAPIDLY WEAKEN WITH
DISSIPATION FORECAST TO OCCUR SOUTH OF HAINAN AROUND TAU 96.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
REGARDING THE LOCATION OF LANDFALL WITHIN THE BALER BAY AREA.
GUIDANCE CONTINUES TO AGREE THROUGH TAU 48 WITH A 75 NM CROSS-TRACK
SPREAD AT THAT TIME. AFTER TAU 48, MODELS BEGIN TO DIVERGE IN BOTH
CROSS-TRACK AND ALONG-TRACK MEASUREMENTS DUE TO DIFFERENCES IN THE
AMOUNT OF WEAKENING AND DISSIPATION TIMELINES. THE GFS
DETERMINISTIC IS AN OUTLIER BEING ESPECIALLY FAST NEAR THE END OF
THE FORECAST PERIOD, TRACKING THE VORTEX INTO EASTERN THAILAND AT
TAU 96. THE JTWC TRACK FORECAST IS PLACED CLOSE TO CONSENSUS
THROUGH TAU 72 AND A BIT SLOWER THEREAFTER TO OFFSET THE GFS.
INTENSITY GUIDANCE IS IN GOOD AGREEMENT WITH A CLOSE GROUPING
BETWEEN HAFS-A, HWRF, AND COAMPS-TC. THE GFS BEING SLIGHTLY LOWER
THAN THEM THROUGHOUT THE FORECAST. THE JTWC INTENSITY FORECAST IS
PLACED CLOSE TO THE MENTIONED PRIMARY GROUPING WITH OVERALL MEDIUM
CONFIDENCE.

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