WDPN31 PGTW 212100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (IN-FA) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.6N 126.2E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 167 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TY 09W
STILL FIGHTING OFF A MASSIVE INTRUSION OF DRY AIR WRAPPING TOWARDS 
THE CORE. THE DRY NORTHERLIES HAVE BEEN DIVING INTO THE WESTERN
SEMICIRCLE FOR THE PAST TWO DAYS AND THE SYSTEM HAS BEEN MARGINALLY 
SUCCESSFUL AT MAINTAINING THE CORE, BUT THE EYEWALL HAS BECOME 
RAGGED. THE CURRENT POSITION IS ASSESSED WITH GOOD CONFIDENCE BASED 
ON AN EYE FIX FROM PGTW. THE CURRENT INTENSITY ASSESSMENT IS BASED 
ON MULTIPLE AGENCY DVORAK ASSESSMENTS. TY 09W IS TRACKING THROUGH AN 
AREA OF LOW VERTICAL WIND SHEAR AND 28-30C SEA SURFACE TEMPERATURES, 
BUT THE SLOW MOVEMENT OF THE SYSTEM IS CHURNING UP SOME COOLER 
WATERS THAT ARE SLOWING INTENSIFICATION. OUTFLOW IS GOOD TO THE 
POLEWARD SIDE BUT ANIMATED WATER VAPOR IMAGERY VERIFIES THAT THE DRY 
AIR WRAPPING ALONG THE EQUATORWARD SIDE OF THE SYSTEM IS SUPPRESSING 
EQUATORWARD OUTFLOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA. TWO SCATTEROMETRY
PASSES AROUND THE 12Z TIME PERIOD ALLOWED FOR CONFIDENT ADJUSTMENT
OF THE WIND RADII.

CURRENT STEERING MECHANISM: THE SOUTHERN FLANK OF A HIGH AMPLITUDE
RIDGE ANCHORED OVER THE SEA OF JAPAN. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.0 - 90 KTS
   CIMSS ADT: 102 KTS AT 211730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-15 KTS
   SST: 28-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT, OCEAN UPWELLING, AND
SUPPRESSED EQUATORWARD OUTFLOW ARE THE FACTORS LIMITING
DEVELOPMENT. 

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: THE RIDGE TO THE NORTH HAS PEAKED AND WILL
WEAKEN AND RETROGRADE OVER THE NEXT 36 HOURS, ALLOWING TYPHOON
IN-FA TO RESUME A MORE POLEWARD TRACK WITHIN THE NEXT 12 HOURS.  AS 
THE SYSTEM ROUNDS THE SOUTHWESTERN PERIPHERY OF THE RIDGE AND AN
UPPER-LEVEL TROUGH DIGS OVER EASTERN CHINA, THE STORM WILL TRACK
TOWARDS EASTERN CHINA.  NUMERICAL MODEL GUIDANCE HAS STEADILY
SHIFTED AWAY FROM TAIWAN AND TOWARDS SHANGHAI OVER THE PAST TWO
DAYS. THE CURRENT JTWC FORECAST STAYS CLOSER TO THE MULTI-MODEL
CONSENSUS, WITH THE STORM MAKING LANDFALL SOUTH OF SHANGHAI AND
DISSIPATING OVER LAND. THE GREATEST UNCERTAINTY IN THE FORECAST IS
WHETHER OR NOT THE STORM TRACKS INLAND OR RECURVES ALONG THE COAST
NEAR SHANGHAI AND TURNS TOWARD THE YELLOW SEA. GIVEN THAT THE
TYPHOON IS CURRENTLY BEING LIMITED BY DRY AIR ENTRAINMENT AND
UPWELLING, THERE IS GOOD CONFIDENCE IN SOME MODERATE
INTENSIFICATION DURING THE NEXT 36 HOURS AS POLEWARD OUTFLOW
INCREASES AND THE STORM TRACKS OVER WARMER WATERS NEAR THE KUROSHIO
CURRENT. 

MODEL DISCUSSION: THE JTWC TRACK FORECAST LIES CLOSE TO THE MODEL
CONSENSUS AND THE ECMWF ENSEMBLE MEAN. THE INTENSITY GUIDANCE IS IN
FAIRLY TIGHT AGREEMENT AND CONSISTENT IN TREND. THE FORECAST STAYS
IN THE MIDDLE OF A THE GUIDANCE PACKAGE.  

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