WDPN31 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (IN-FA) WARNING NR 033//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.3N 124.3E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 195 NM WEST OF KADENA AIR BASE
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE
SIGNATURE OF A LARGE TYPHOON THAT HAS BEEN LIMITED BY COLD WATER,
UPWELLED DUE TO SLOW MOVEMENT DURING THE LAST COUPLE DAYS. THE
INNER CORE IS BROAD AND RAGGED, WITH A RADIUS OF MAXIMUM WINDS OF
APPROXIMATELY 40 NM. THE COLD CONVECTIVE RING ENCIRCLING THE EYE
HAS BEEN DISCONTINUOUS WITH NUMEROUS GAPS. WHILE AGENCY DVORAK
INTENSITY ESTIMATES HAVE INCREASED DURING THE PAST SIX HOURS, A
240145Z ASCAT-B SCATTEROMETER PASS AND A 240421Z AMSR2 MICROWAVE
PASS DID NOT SUPPORT WINDS ABOVE 65 KT. THE CURRENT INTENSITY IS
THUS HELD AT 65 KT. A STATION MEASUREMENT OF 51 KT SUSTAINED WINDS
WAS RECENTLY OBSERVED AT 240600Z IN THE DACHEN ISLANDS OFFSHORE OF
CHINA.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: MID-LEVEL RIDGE OVER THE SEA OF JAPAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   CIMSS SATCON: 74 KTS AT 240214Z
   CIMSS ADT: 69 KTS AT 240540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TYPHOON 09W (IN-FA) CONTINUES TO MOVE MORE
BRISKLY NORTH-NORTHWESTWARD ACROSS THE EAST CHINA SEA, STEERED BY
THE DEEP-LAYER RIDGE OVER THE SEA OF JAPAN, AND IS EXPECTED TO
REACH THE COASTLINE OF CHINA IN ABOUT 24 HOURS JUST SOUTH OF
HANGZHOU BAY. THE TYPHOON'S FORWARD MOTION IS CARRYING IT AWAY FROM
THE POOL OF UPWELLED COLD WATER THAT HAS DEVELOPED SOUTHEAST OF THE
RYUKYU ISLANDS ACCORDING TO COUPLED OCEAN ANALYSIS FROM THE HWRF
MODEL. THE SHALLOWER EAST CHINA SEA PRESENTS A NEW HEAT SOURCE TO
THE CYCLONE, BUT THE ALREADY BROADENED INNER CORE IS NOW HIGHLY
INERTIALLY STABLE AND UNLIKELY TO STRENGTHEN SIGNIFICANTLY PRIOR TO
LANDFALL. THE JTWC INTENSITY FORECAST HOLDS THE INTENSITY AT 65 KT
UNTIL THAT TIME, FOLLOWED BY OVERLAND DECAY UNTIL DISSIPATION
BETWEEN 96 AND 120 HOURS. TYPHOON IN-FA SHOULD SLOW DOWN AFTER
LANDFALL AS THE STEERING RIDGE TO THE NORTHEAST WEAKENS AND
UPPER-LEVEL TROUGHING BECOMES ESTABLISHED OVER MONGOLIA. A TURN TO
THE NORTH OR NORTHEAST AFTER 72 HOURS MAY EVENTUALLY CARRY IN-FA OR
ITS REMNANTS BACK OFFSHORE EAST OF CHINA, BUT THIS SCENARIO IS OF
LOW CONFIDENCE DUE TO THE WEAK STEERING CURRENTS CURRENTLY
FORECAST.

MODEL DISCUSSION: THE JTWC TRACK FORECAST IS GENERALLY CLOSE TO THE
MULTI-MODEL CONSENSUS. THE INTENSITY FORECAST IS SLIGHTLY ABOVE THE
MULTI-MODEL CONSENSUS PRIOR TO LANDFALL. NUMERICAL MODEL TRACK
SPREAD INCREASES MARKEDLY AFTER 72 HOURS DUE TO WEAK STEERING
CURRENTS.

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