WDPN32 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 19W (CHANTHU) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.7N 127.2E
   INITIAL INTENSITY: 130 KTS
   GEOGRAPHIC REFERENCE: 365 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 53 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT
SYSTEM WITH ROBUST RADIAL OUTFLOW AND A FADING 5-NM PINHOLE EYE,
GIVING HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL
INTENSITY IS BASED ON MULTI-AGENCY DVORAK INTENSITY ESTIMATES, AS
WELL AS ADT AND SATCON, WHICH ALL INDICATE THE START OF A SLIGHT
WEAKENING TREND. THIS MAY BE DUE TO A POSSIBLE EYEWALL REPLACEMENT
CYCLE, WHICH IS EVIDENT IN A 2202Z 91GHZ SSMIS IMAGE DEPICTING A
SECOND EYEWALL FORMING. A MORE RECENT 0515Z 89GHZ AMSR2 IMAGE SHOWS
THE SECOND EYEWALL HAS CONSTRICTED TO ABOUT 30 NM IN DIAMETER.
THEREFORE, A SLIGHT INTENSIFICATION IS PROBABLE.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T7.0 - 140 KTS 
   RCTP: T6.0 - 115 KTS
   KNES: T6.5 - 127 KTS
   CIMSS SATCON: 134 KTS AT 090121Z
   CIMSS ADT: 129 KTS AT 090540Z

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: MEDIUM

3. FORECAST REASONING.

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

FORECAST DISCUSSION: SUPER TYPHOON (STY) 19W IS BEGINNING A MORE
WEST-NORTHWESTWARD TRACK AS IT BEGINS TO ROUND THE WESTERN EDGE OF
THE SUBTROPICAL RIDGE. AFTER TAU 48, THE SYSTEM WILL CROSS TAIWAN
AS IT TRACKS NORTHWARD AND EVENTUALLY CRESTS THE SUBTROPICAL RIDGE
AXIS. AFTER TAU 96, THE SYSTEM WILL TURN NORTH-NORTHEASTWARD ON THE
POLEWARD SIDE OF THE SUBTROPICAL RIDGE. STY 19W WILL REMAIN IN A
FAVORABLE ENVIRONMENT FOR THE EARLY PART OF THE FORECAST,
SUSTAINING IT ABOVE 130 KTS UNTIL ABOUT TAU 48, AT WHICH POINT LAND
INTERACTION WITH TAIWAN WILL BEGIN TO WEAKEN IT. THE SYSTEM WILL 
WEAKEN TO 100KTS AS IT EXITS INTO THE TAIWAN STRAIT AROUND TAU 72. 
AFTERWARDS, INCREASING VERTICAL WIND SHEAR AND DECREASING SEA 
SURFACE TEMPERATURES WILL FURTHER WEAKEN THE SYSTEM TO 60 KTS BY TAU 
120.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT IN REGARDS
TO THE RECURVATURE TRACK FORECAST SOLUTION WITH ONLY A 220 NM
CROSS-TRACK SPREAD AT TAU 120. WHILE THERE IS ALSO GOOD AGREEMENT
IN THE INTENSITY GUIDANCE, THE FORECAST INTENSITY IS HELD SLIGHTLY
HIGHER THAN THE CONSENSUS TO ACCOUNT FOR THE PROBABLE SLIGHT
INTENSIFICATION FOLLOWING THE EYEWALL REPLACEMENT CYCLE.  


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