WDPN32 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (SAOLA) WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.0N 123.7E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 177 NM EAST-NORTHEAST OF MANILA,
       PHILIPPINES
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 09W HAS WEAKENED CONSIDERABLY OVER THE PAST SIX HOURS
WITH THE RECENT LOSS OF THE EYE AND A SHRINKING, MORE ASYMMETRIC
CONVECTIVE CORE AS DEPICTED IN THE ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY. A 271656Z AMSR2 89 GHZ MICROWAVE IMAGE REVEALS A
SMALL MICROWAVE EYE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH
CONFIDENCE, AND AN ASYMMETRIC CORE WITH DECAYING DEEP CONVECTION
OVER THE NORTHERN QUADRANT. THE EYEWALL REMAINS INTACT BUT HAS A
DEVELOPING BREAK OVER THE NORTH QUADRANT. THE CIMSS M-PERC PRODUCT
SHOWS INCREASING PROBABILITIES (90-100 PERCENT) FOR AN EYEWALL
REPLACEMENT CYCLE (ERC), HOWEVER, HIGH RESOLUTION MICROWAVE IMAGERY
HAS BEEN SPARSE SO IT'S DIFFICULT TO VERIFY AN ERC. ADDITIONALLY,
INTERACTION WITH LAND AND UPWELLING COOLER WATER ARE ALSO
CONTRIBUTING TO THE RECENT WEAKENING TREND. THE INITIAL INTENSITY
OF 110 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE CURRENT
INTENSITY ESTIMATES FROM PGTW, KNES AND RJTD.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL (NER) RIDGE ENTRENCHED
TO THE SOUTH WITH A WEAK EXTENSION OF THE NER TO THE EAST,
SEPARATING 09W FROM A DEVELOPING TROPICAL SYSTEM (INVEST 93W) NEAR
THE NORTHERN MARIANAS. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   CIMSS ADT: 102 KTS AT 271730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY 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: BASED ON THE CLEAR WEAKENING TREND,
FORECAST INTENSITIES THROUGH TAU 36 HAVE BEEN DECREASED
SIGNIFICANTLY.

FORECAST DISCUSSION: TY 09W HAS STARTED TO SLOWLY TURN EASTWARD AND
NOW APPEARS TO BE TURNING EAST-NORTHEASTWARD AS EXPECTED. 09W IS
FORECAST TO ACCELERATE POLEWARD OVER THE NEXT 24 HOURS. FURTHER
WEAKENING IS EXPECTED OVER THE NEXT 12 HOURS THEN A STEADY
REINTENSIFICATION PHASE SHOULD OCCUR AS THE SYSTEM TRACKS AWAY FROM
LUZON AND OVER WARMER SST. AFTER TAU 24, STEERING SHOULD TRANSITION
FROM THE NER TO A BUILDING SUBTROPICAL RIDGE (STR) OVER THE EAST
CHINA SEA. THIS WILL ALLOW TY 09W TO TRACK WEST-NORTHWESTWARD
THROUGH TAU 120. THE STR, ESPECIALLY THE WESTERN EXTENT, SHOULD
REMAIN WEAK DUE TO THE PRESENCE OF A STRONG, BROAD UPPER LEVEL LOW
AND TROUGH DEVELOPING OVER NORTHEAST ASIA THUS TRACK SPEEDS WILL
REMAIN CLIMATOLOGICALLY SLOW. TY 09W WILL PEAK NEAR 125 KNOTS BY
TAU 72 WITH STEADY WEAKENING IN THE EXTENDED FORECAST PERIOD DUE TO
INTERACTION WITH TAIWAN AND SOUTHEAST CHINA.

MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, NUMERICAL MODEL
GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 LENDING HIGH
CONFIDENCE TO THE JTWC FORECAST TRACK. AFTER TAU 72, TRACK GUIDANCE
DIVERGES WITH A 320 NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 120.
THIS INCREASING UNCERTAINTY AND LOW TRACK CONFIDENCE IS REFLECTED
IN THE 271200Z EPS AND GEFS ENSEMBLES, WHICH SHOW A LARGE SPREAD.
BOTH THE GFS DETERMINISTIC SOLUTION AND GEFS ENSEMBLE SUGGEST A
PROBLEMATIC, POTENTIAL SCENARIO WHERE INVEST 93W STRENGTHENS AND
TRACKS WESTWARD TOWARD TAIWAN, CLOSING TO ABOUT 590 NM AT TAU 120.
SOME DEGREE OF INTERACTION THEN OCCURS BETWEEN THE TWO SYSTEMS.
THIS POTENTIAL SCENARIO IS COMPLEX AND WILL BE MONITORED CLOSELY.

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