WDPN32 PGTW 270900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (SAOLA) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.8N 123.0E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 175 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 38 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A
MEDIUM-SIZED, HIGHLY-SYMMETRICAL SYSTEM THAT HAS MAINTAINED DEEP
CONVECTION AROUND THE EYEWALL AS IT MAINTAINED A 13-NM, SHARPLY
OUTLINED EYE THAT WAS CONCENTRIC WITH A DEFINED CIRCULATION ON A
COMPOSITE WEATHER RADAR LOOP. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE EYE. THE INITIAL INTENSITY OF 115KTS IS 
ASSESSED WITH HIGH CONFIDENCE BASED ON OVERALL ASSESSMENT OF AGENCY 
AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SUSTAINED INTENSE 
CONVECTIVE STRUCTURE. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH 
VERY WARM SST IN THE PHILIPPINE SEA, LOW VWS, AND MODERATE RADIAL
OUTFLOW ALOFT, OFFSET ONLY BY LOCALIZED OCEAN UPWELLING.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE WEST AND
NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T6.5 - 127 KTS
   KNES: T6.0 - 115 KTS
   CIMSS ADT: 112 KTS AT 2720500Z
   CIMSS D-MINT: 114 KTS AT 270341Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE 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: TY SAOLA WILL BEGIN TO SLOWLY TRACK EASTWARD
AS THE NER TO THE SOUTH ASSUMES STEERING. AROUND TAU 24, A NORTH-SOUTH 
EXTENSION OF A SECONDARY DEEP-LAYER STR TO THE NORTHEAST WILL ASSUME 
STEERING AND DRIVE THE SYSTEM NORTHWARD, THEN AFTER TAU 36, THIS SAME 
STR WILL BUILD AND SPEED UP THE SYSTEM NORTHWESTWARD TOWARD TAIWAN VIA
THE LUZON STRAIT. THE FAVORABLE ENVIRONMENT, TEMPERED BY LOCALIZED 
OCEAN UPWELLING, WILL BECOME MARGINAL WITH THE ONSET OF DRY AIR 
INTRUSION IN THE LOW LEVELS AND WILL GRADUALLY WEAKEN THE SYSTEM TO 
105KTS BY TAU 24. AFTERWARD, AS THE CYCLONE TURNS NORTHWARD AND SPEEDS 
UP, OCEAN UPWELLING AND DRY AIR INTRUSION WILL DIMINISH AND FUEL A 
SECONDARY INTENSIFICATION TO A PEAK OF 130KTS AROUND TAU 72. AFTER
TAU 72, INCREASING VWS AND LAND INTERACTION WILL GRADUALLY WEAKEN
THE SYSTEM DOWN TO 90KTS BY TAU 120 AFTER IT CROSSES THE TAIWAN
STRAIT AND MAKES LANDFALL OVER EASTERN CHINA NORTHEAST OF HONG
KONG. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH THIS LOOPING TRACK FORECAST WITH A GRADUAL SPREAD TO JUST
100NM AT TAU 72 THEN TO 253NM AT TAU 120, SANS NAVGEM, THE EXTREME
LEFT-OF-TRACK OUTLIER. THERE IS OVERALL MEDIUM CONFIDENCE IN THE
JTWC TRACK FORECAST THAT IS LAID JUST TO THE RIGHT OF CONSENSUS TO
OFFSET NAVGEM.  



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