WDPN32 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (SAOLA) WARNING NR 
026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.1N 121.1E
   INITIAL INTENSITY: 135 KTS
   GEOGRAPHIC REFERENCE: 408 NM EAST-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION, AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A ROBUST,
SYMMETRIC CONVECTIVE STRUCTURE SURROUNDING A 15 NM EYE. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE ON THE EYE, WHILE THE
INITIAL INTENSITY OF 135 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED
ON SUPPORTIVE SUBJECTIVE DVORAK INTENSITY ESTIMATES OF T7.0 FROM
ALL REPORTING AGENCIES AS WELL AS OBJECTIVE ESTIMATES INCLUDING D-
PRINT, D-MINT, AND AIDT IN THE 125-135 KNOT RANGE. THE SYSTEM HAS
MAINTAINED INTENSITY OVER THE PAST SIX HOURS WITH SUPPORT FROM
PASSAGE OVER VERY WARM WATER AND DUAL CHANNEL OUTFLOW, PARTICULARLY
ON THE EQUATORWARD SIDE.

INITIAL WIND RADII BASIS: PERSISTENCE AND OBJECTIVE BEST TRACK 

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 292330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE 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 09W WILL CONTINUE TRACKING GENERALLY
WESTWARD THROUGHOUT THE FORECAST PERIOD. THE TRACK IS EXPECTED TO
TAKE A BIT OF A POLEWARD BEND IN THE NEAR-TERM, TOWARD A WEAKNESS
IN THE RIDGE INDUCED BY A MID-LATITUDE TROUGH ANALYZED OVER EASTERN
CHINA. AS THIS TROUGH TRANSLATES EASTWARD, AN EXTENSION OF THE
CURRENT STEERING STR WILL BUILD TO THE NORTH OF 09W. INTENSITY WILL
LIKELY REMAIN AT OR NEAR THE SUPER TYPHOON LEVEL OVER THE NEXT TWO
DAYS WITH FAVORABLE ENVIRONMENTAL SUPPORT, ALTHOUGH A POSSIBLE
EYEWALL REPLACEMENT CYCLE, SHOULD ONE OCCUR, COULD KNOCK THE
INTENSITY DOWN A BIT FURTHER THAN REFLECTED IN THE CURRENT FORECAST
DURING THIS PERIOD. LATER IN THE FORECAST, AFTER TAU 48,
INTERACTION OF THE NORTHERN PORTION OF THE CIRCULATION WITH LAND,
INCREASING VERTICAL WIND SHEAR AND A LESS FAVORABLE OUTFLOW PATTERN
WILL CONTRIBUTE TO A MORE PRONOUNCED WEAKENING TREND.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
REGARDING THE OVERALL TRACK AND INTENSITY FORECAST SCENARIO. THE
ECMWF DETERMINISTIC MODEL, ECMWF ENSEMBLE MEAN, AND JGSM MODEL
SOLUTIONS LIE A BIT FARTHER TO THE NORTH OF THE PRIMARY MODEL
GROUPING AND CARRY THE SYSTEM ALONG THE SOUTHERN COAST OF CHINA TO
THE EAST AND OVER HONG KONG, A PLAUSIBLE BUT LOWER PROBABILITY
SCENARIO THAN AN OFFSHORE TRACK ON THIS FORECAST CYCLE. GIVEN THIS
UNCERTAINTY REGARDING POTENTIAL LANDFALL, TRACK FORECAST CONFIDENCE
IS ASSESSED AS ONLY MEDIUM DESPITE RATHER LIMITED SPREAD. INTENSITY
FORECAST CONFIDENCE IS ALSO ASSESSED AS MEDIUM GIVEN UNCERTAINTY IN
THE EFFECTS OF LANDFALL INTERACTIONS AND THE POTENTIAL FOR AN
EYEWALL REPLACEMENT CYCLE.

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