WDPN31 PGTW 241500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (IN-FA) WARNING NR 034//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.0N 124.0E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 224 NM WEST-NORTHWEST OF KADENA AIR BASE
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS LITTLE
CHANGE IN THE TYPHOON'S STRUCTURE DURING THE PAST SIX HOURS. CORE
CONVECTION REMAINS RAGGED AND BROKEN, WITH MID-LEVEL CLOUDS
INTERMITTENTLY COVERING THE EYE. THE INITIAL INTENSITY IS HELD AT
65 KT BASED ON EARLIER SCATTEROMETER AND MICROWAVE DATA THAT
SUGGEST THE CURRENT INTENSITY IS LOWER THAN CONVENTIONAL DVORAK
ESTIMATES. THIS WOULD ALSO BE CONSISTENT WITH THE ABNORMALLY BROAD
CORE WIND FIELD, WHICH IS USUALLY ASSOCIATED WITH LOWER PEAK WINDS
THAN IS TYPICAL. A NEAR-SURFACE WIND OF 56 KT WAS RECENTLY OBSERVED
IN THE DACHEN DAO ISLANDS AT 241200Z, JUST OFFSHORE OF TAIZHOU, ABOUT
115 NM WEST OF THE EYE. THE OVERALL ENVIRONMENT IS FAVORABLE FOR
INTENSIFICATION WITH LOW VERTICAL SHEAR AND WARM SEA SURFACE
TEMPERATURES. THE PRIMARY LIMITATION ON THE TYPHOON IS ITS LARGE,
SPRAWLING STRUCTURE, WHICH RESISTS SPIN-UP.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYER 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 ADT: 72 KTS AT 241140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 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 DRAW CLOSER
TO CHINA, STEERED BY
THE DEEP-LAYER RIDGE OVER THE SEA OF JAPAN, AND IS EXPECTED TO
REACH THE COASTLINE IN 24 HOURS OR LESS, MAKING LANDFALL NEAR THE
SOUTHERN EDGE OF HANGZHOU BAY. NO SIGNIFICANT CHANGE IN INTENSITY
IS EXPECTED BEFORE LANDFALL, AS WHILE THE ENVIRONMENT IS GENERALLY
FAVORABLE, THE TYPHOON'S BROAD INNER CORE WIND FIELD MAKES
INTENSIFICATION DIFFICULT OVER THE SHORT TIME PERIOD REMAINING
BEFORE LANDFALL. IN-FA WILL WEAKEN AFTER LANDFALL, AND IS FORECAST
TO DISSIPATE 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 COULD 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. THE JTWC FORECAST IS SIMILAR TO THE PREVIOUS ONE.

MODEL DISCUSSION: THE JTWC TRACK AND INTENSITY FORECAST IS SIMILAR
TO THE PREVIOUS ONE. THE INTENSITY FORECAST IS SLIGHTLY ABOVE THE
MULTI-MODEL CONSENSUS FOR THE FIRST 24-36 HOURS.

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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