WDPN32 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (SAOLA) WARNING NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.0N 123.2E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 240 NM NORTH-NORTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 46 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A
MEDIUM-SIZED, HIGHLY-SYMMETRICAL SYSTEM THAT HAS MOSTLY SUSTAINED
ITS INTENSE CONVECTIVE STRUCTURE WITH THE ADDITION OF A 10-NM,
SHARPLY OUTLINED EYE. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE EYE. THE INITIAL INTENSITY OF 105KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE HIGH END OF AGENCY AND
AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SLIGHT 6-HR
IMPROVEMENT. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH VERY
WARM SST IN THE PHILIPPINE SEA, LOW VWS, AND MODERATE RADIAL
OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE WEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 97 KTS AT 260700Z
   CIMSS ADT: 94 KTS AT 260700Z
   CIMSS D-PRINT: 99 KTS AT 260700Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: DYNAMIC OCEAN COOLING.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY SAOLA WILL CONTINUE ON ITS CURRENT TRACK
UNDER THE STR TO THE WEST. AFTER TAU 12, A NEAR EQUATORIAL RIDGE TO
THE SOUTH WILL ASSUME STEERING AND DRIVE THE CYCLONE EASTWARD.
AROUND TAUS 36-48, A NORTH-SOUTH EXTENSION OF A SECONDARY
DEEP-LAYER STR TO THE NORTHEAST WILL ASSUME STEERING AND DRIVE THE
SYSTEM POLEWARD, THEN AROUND TAU 72, THIS SAME STR WILL BUILD AND
ACCELERATE THE SYSTEM NORTHWESTWARD TOWARD TAIWAN VIA THE LUZON
STRAIT. THE FAVORABLE ENVIRONMENT, TEMPERED ONLY BY LOCALIZED OCEAN
UPWELLING, WILL PROMOTE FURTHER INTENSIFICATION TO A PEAK OF 120KTS
BY TAU 36. AFTERWARD, INCREASED UPWELLING AND THE ONSET OF DRY AIR
INTRUSION AT THE LOW LEVELS WILL GRADUALLY WEAKEN THE SYSTEM DOWN
TO 90KTS BY TAU 120 AS IT REACHES THE TAIWAN STRAIT WHERE LAND
INTERACTION AND INCREASING VWS BEGIN TO CONTRIBUTE TO THE
CONVECTIVE EROSION OF SAOLA. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH THIS LOOPING TRACK FORECAST WITH A GRADUAL SPREAD TO 176NM AT
TAU 72 THEN 295NM AT TAU 120. JGSM IS THE NOTABLE RIGHT-OF-TRACK
OUTLIER AND GFS IS ON THE LEFT MARGIN OF THE MODEL ENVELOPE AFTER
TAU 72. THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST.  

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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