WDPN32 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (SAOLA) WARNING NR 
025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.9N 121.9E
   INITIAL INTENSITY: 135 KTS
   GEOGRAPHIC REFERENCE: 313 NM SOUTH OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 46 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (MSI) DEPICTS A VERY
SYMMETRIC SUPER TYPHOON WITH AN 11NM WIDE STADIUM EYE AND A
SINGULAR WIDE BAND OF CONVECTION COMPLETELY SURROUNDING THE EYE
FEATURE. THE SYSTEMS TIGHT AND BALANCED STRUCTURE IS CAPTURED WELL IN 
A 291745Z ATMS 183GHZ MICROWAVE IMAGE. ANIMATED WATER VAPOR IMAGERY 
SHOWS MOST OF THE OUTFLOW ALOFT TO BE EQUATORWARD, WITH MINOR RADIAL 
OUTFLOW FROM THE WESTERN PERIPHERY. THE INITIAL POSITION IS ASSESSED 
WITH HIGH CONFIDENCE BASED ON THE EYE IN A 291800Z HM9 PROXYVIS IMAGE. 
THE INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE BASED ON AN 
OVERALL ASSESSMENT OF THE AGENCY CURRENT INTENSITY ESTIMATES OF T7.0 
AND SUBJECTIVE INTENSITY ESTIMATES BETWEEN 131 AND 134 KNOTS. THE 
SYSTEM IS MOVING NORTHWEST ALONG THE SOUTHWESTERN EDGE OF A DEEP 
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.

INITIAL WIND RADII BASIS: PERSISTENCE.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T7.0 - 140 KTS 
   RCTP: T7.0 - 140 KTS 
   KNES: T7.0 - 140 KTS 
   CIMSS ADT: 134 KTS AT 291730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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: STY SAOLA IS FORECAST TO CONTINUE ON A
WEST-NORTHWESTWARD TRACK THROUGH TAU 72, WHERE IT GRADUALLY TURNS TO A
MORE WEST-SOUTHWESTWARD TRACK THROUGH TAU 120. SSTS WILL GRADUALLY
DECLINE ALONG THE FORECASTED TRACK STARTING AS EARLY AS TAU 18,
INHIBITING STORM GROWTH INITIALLY AND THEN CONTRIBUTING TO THE
GRADUAL WEAKENING OF INTENSITY AND STRENGTH. FURTHERMORE, 
VERTICAL WIND SHEAR (VWS) IS ANTICIPATED TO GREATLY INCREASE AROUND 
TAU 96. THE HIGHER VWS, ALONG WITH POTENTIAL LAND INTERACTION OF THE 
OUTERMOST WIND FIELD, COULD ALSO CONTRIBUTE TO THE SYSTEMS DECAY IN 
THE TAU 96 TO TAU 120 INTERVAL.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN MODERATE AGREEMENT
THAT STY SAOLA WILL TRACK WEST-NORTHWESTWARD THROUGH TAU 72, AND
THEN TRACK MORE WEST-SOUTHWESTWARD THROUGH TAU 120. THE JGSM DIVERGES
QUICKLY TO THE NORTH AT TAU 72, WITH THE OPPOSING SOLUTION OF NAVGEM 
DIVERGING MORE SUBTLY TO THE SOUTHWEST AT THE SAME INTERVAL. A 63NM 
CROSS-TRACK SPREAD, WITH LITTLE ALONG-TRACK SPREAD, CONTRIBUTE TO 
TRACK CONFIDENCE THROUGH TAU 72. CONVERSELY, DUE TO THE TAU 120 410NM 
CROSS-TRACK SPREAD, TRACK AND INTENSITY FORECAST CONFIDENCE POST TAU 
72 IS LOW.

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