Tropical Storm IN-FA Advisory 7月24日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (IN-FA) WARNING NR
031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 25.4N 124.9E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 170 NM WEST-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY VERIFIES THAT A
CONCENTRIC BUT FRAGMENTED EYEWALL REMAINS INTACT BUT DEEP
CONVECTION IS NOT CONTINUOUS AROUND THE EYE, WHICH HAS CONTRACTED
FROM OVER 60NM 24 HOURS PREVIOUSLY TO ITS PRESENT 43NM. A 231726Z
AMSR2 SERIES REVEALS THAT THE ONLY DEEP CONVECTION REMAINING IS
OVER THE NORTHEAST QUADRANT OF THE EYEWALL. DURING PASSAGE OVER THE
SOUTHERN SENKAKUS SURFACE REPORTS DID NOT EXCEED 45KTS AND A
231318Z SCATTEROMETRY PASS JUST AFTER THE STORM CLEARED THE
SENKAKUS SHOWED A DEARTH OF STORM FORCE WINDS.  DVORAK ESTIMATES
OVER THE PAST 24 HOURS HAVE BEEN HIGHER THAN ACTUAL REPORTS. FROM
MULTIPLE AGENCY DVORAK ESTIMATES, THE CURRENT INTENSITY IS ADJUSTED
LOWER WHICH IS SUPPORTED BY A MUCH LOWER ADT ESTIMATE OF
45KTS.
INITIAL WIND RADII BASIS: 231318Z METOP-A.
CURRENT STEERING MECHANISM: THE SOUTHWESTERN PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) CENTERED JUST OFF THE EAST
COAST OF THE KOREAN PENINSULA.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T4.0 - 65 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 45 KTS AT 231740Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 27-29 CELSIUS
   OUTFLOW: MODERATE RADIAL
ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TY 09W IS TRACKING STEADILY NORTHWESTWARD
TOWARDS THE EAST COAST OF CHINA, MOVING QUICKLY ENOUGH TO NO LONGER
GENERATE UPWELLING. IT WILL PEAK IN INTENSITY AT LOW TYPHOON STATUS
DURING THERE 24 HOURS. A BUILDING RIDGE TO THE NORTH WILL STEER THE
STORM ON A MORE WESTWARD TRACK AS IT APPROACHES SHANGHAI, DRIVING
THE SYSTEM INLAND SOUTH OF SHANGHAI.  A POCKET OF MUCH COOLER WATER
ON THE FINAL OVER WATER STRETCH WILL RESULT IN THE SYSTEM MAKING
LANDFALL WELL BELOW TYPHOON STRENGTH.
MODEL DISCUSSION: THERE IS INCREASING CONVICTION IN THE WESTWARD
LEG AND LANDFALL SOUTH OF CHINA SCENARIO. MEMBERS OF THE
MULTI-MODEL CONSENSUS HAVE BEEN FOCUSING MORE TIGHTLY INTO A PACK
SOUTH OF SHANGHAI WITH EACH PASSING CYCLE. THE ECMWF ENSEMBLE MEANS
HAVE BEEN LOCKED IN ON THAT SCENARIO FOR OVER THREE DAYS AND THE
GEFS ENSEMBLE IS COMING TOWARDS THE ECMWF ENSEMBLE. THE FORECAST
STAYS IN THE MIDDLE OF THE PACK THROUGH LANDFALL, THEN FOLLOWS
CONSENSUS DURING THE DISSIPATION OVER LAND PHASE.
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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