Tropical Storm IN-FA Advisory zo, 25-07

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (IN-FA) WARNING NR 036//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 29.7N 122.9E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 116 NM SOUTHEAST OF SHANGHAI, CHINA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS FEEDER
BAND CONVECTIVE TOPS CONTINUED TO WARM UP AND UNRAVEL; HOWEVER THE
CENTRAL DENSE OVERCAST FEATURE REMAINS INTACT AND MAINTAINED A
LARGE 40NM RAGGED EYE. THE INITIAL INTENSITY IS PLACED WITH HIGH
CONFIDENCE BASED ON THE EYE THAT WAS COINCIDED WITH AN LLC
FEATURE IN A CMA COMPOSITE RADAR LOOP. THE INITIAL INTENSITY OF
65KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON OVERALL ASSESSMENT
OF AGENCY AND AUTOMATED DVORAK FIXES TO REFLECT THE DETERIORATING
CONVECTIVE STAGE BUT MAINTAINED THE TYPHOON INTENSITY.
INITIAL WIND RADII BASIS: PERSISTENCE.
CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.
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: 43 KTS AT 242340Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 WILL TURN MORE WESTWARD AFTER TAU
12 AND MAKE LANDFALL JUST SOUTH OF SHANGHAI, TRACK INLAND, THEN
RECURVE NORTHEASTWARD AFTER TAU 72 IF IT MAINTAINS ITS LOW LEVEL
STRUCTURE. THE DEGRADING ENVIRONMENT CAUSED BY COOLING SSTS AND
LAND INTERACTION WILL GRADUALLY THEN RAPIDLY WEAKEN THE SYSTEM DOWN
TO 25KTS BY TAU 120 AS IT APPROACHES THE YELLOW SEA.
MODEL DISCUSSION: NUMERICAL MODELS DIVERGE SIGNIFICANTLY AFTER
LANDFALL, SPREADING OUT TO OVER 260NM BY TAU 72 THEN DIVERGE
SIGNIFICANTLY AFTERWARD, LENDING HIGH CONFIDENCE TO THE JTWC TRACK
FORECAST UP TO TAU 72 ONLY. THE SPREAD NARROWS DOWN TO UNDER 200NM
BY TAU 120 BUT ALONG-TRACK SPEEDS WIDELY VARY.
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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