WDPN32 PGTW 311500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (SAOLA) WARNING NR 
032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.4N 117.3E
   INITIAL INTENSITY: 130 KTS
   GEOGRAPHIC REFERENCE: 181 NM EAST-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 50 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
HAS MAINTAINED A HIGHLY SYMMETRICAL AND DENSE CENTRAL CONVECTION;
HOWEVER, THE OUTER EYEWALL HAS OPENED UP ALONG THE NORTHERN
QUADRANT AS IT STRUGGLES TO ENVELOPE AND REPLACE THE INNER EYEWALL
WITH ITS SHARPLY OUTLINED 20-NM EYE. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE EYE. THE INITIAL INTENSITY OF
130KTS IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON AN OVERALL
ASSESSMENT OF AGENCY DVORAK ESTIMATES AND REFLECTS THE SLIGHT 6-HR
CONVECTIVE DETERIORATION NEAR THE CORE. ANALYSIS INDICATES A
FAVORABLE ENVIRONMENT WITH VERY WARM SST IN THE SOUTH CHINA SEA,
LOW VWS, AND STRONG RADIAL OUTFLOW. ADDITIONALLY, STY 09W IS SLOWLY
UNDERGOING AN EYEWALL REPLACEMENT CYCLE (ERC) WHICH HAS
SLIGHTLY WEAKENED THE SYSTEM.

INITIAL WIND RADII BASIS: PERSISTENCE.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T6.5 - 127 KTS
   KNES: T6.5 - 127 KTS
   CIMSS ADT: 122 KTS AT 311130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD AND 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 WILL TRACK WEST-NORTHWESTWARD TO
WESTWARD TRAJECTORY UNDER THE STEERING STR TO THE NORTH. AFTER TAU
36, A SECONDARY STR TO THE WEST WILL ASSUME STEERING AND DRIVE THE
CYCLONE SOUTHWESTWARD. THE ERC IS EXPECTED TO CONTINUE TO SLOWLY
WEAKEN THE CORE OF STY 10W; THIS, IN ADDITION TO LAND INTERACTION
WITH THE EASTERN SEABOARD OF CHINA WILL LEAD TO A GRADUAL WEAKENING
TO 70KTS BY TAU 36 AFTER IT BRUSHES HONG KONG. AFTER TAU 36, A MORE
RAPID EROSION IS EXPECTED AS COOL DRY AIR FROM THE CHINESE INTERIOR
INTRUDES INTO THE LOW LEVEL CIRCULATION, KNOCKING DOWN THE
INTENSITY TO 40KTS BY TAU 72. AFTERWARD, A SCALED DOWN AND WEAKER
35-KT 09W WILL LOOP AND DRIFT NORTHEASTWARD WITH THE MONSOON FLOW,
STEERED BY A SHALLOW NEAR-EQUATORIAL RIDGE TO THE SOUTH.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL AGREEMENT WITH
THE LOOPING TRACK BUT DIVERGE SIGNIFICANTLY AFTER TAU 72, LENDING
MEDIUM CONFIDENCE TO THE JTWC TRACK FORECAST UP TO TAU 72, THEN LOW
CONFIDENCE AFTERWARD. NOTABLE OUTLIERS INCLUDE UKMET AND ECMWF THAT
CONTINUE TO DRIVE THE VORTEX SOUTHWESTWARD TOWARD VIETNAM AFTER TAU
72. ANOTHER NOTABLE OUTLIER IS GFS WITH A MUCH WIDER LOOP AFTER TAU 
72. 

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