Tropical Storm HINNAMNOR Advisory 9月1日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (HINNAMNOR) WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 24.0N 126.5E
   INITIAL INTENSITY: 125 KTS
   GEOGRAPHIC REFERENCE: 166 NM SOUTH-SOUTHWEST OF KADENA AB,
OKINAWA, JAPAN
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 50 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A HIGHLY
SYMMETRICAL COMPACT SYSTEM, VOID OF FEEDER BANDS, THAT HAS RECENTLY
UNDERGONE AN EYEWALL REPLACEMENT CYCLE WITH A NEW WELL-DEFINED
10-NM EYE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE EYE IN THE EIR LOOP AND ALSO IN THE COMPOSITE RADAR
LOOP FROM JMA. THE INITIAL INTENSITY IS ALSO PLACED WITH HIGH
CONFIDENCE BASED ON OVERALL ASSESSMENT OF AGENCY AND AUTOMATED
DVORAK ESTIMATES AND CONSISTENT WITH THE 6-HR SUSTAINED EIR
STRUCTURE. THE ENVIRONMENT REMAINS FAVORABLE WITH LOW VWS, STRONG
RADIAL OUTFLOW AND WARM SSTS.
INITIAL WIND RADII BASIS: PERSISTENCE.
CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE NORTHWEST.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T6.5 - 127 KTS
   RJTD: T6.5 - 127 KTS
   CIMSS SATCON: 131 KTS AT 311748Z
   CIMSS ADT: 129 KTS AT 311740Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG RADIAL
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: TY HIMMNAMNOR WILL BEGIN TO SLOW DOWN THEN
BECOME QUASI-STATIONARY (QS) AS A BUILDING STR TO THE NORTHWEST AND
A NEAR EQUATORIAL RIDGE COMPETE FOR STEERING AGAINST THE CURRENT
STEERING STR TO THE NORTH THAT WILL WEAKEN AND RECEDE EASTWARD WITH
THE APPROACH OF A MID-LATITUDE TROUGH FROM THE WEST. AFTER TAU 36,
THE CURRENT STR, NOW POSITIONED TO THE NORTHEAST WILL RE-BUILD AND
REGAIN STEERING, DRIVING THE SYSTEM NORTHWARD THEN
NORTH-NORTHEASTWARD TOWARD SOUTH KOREA. COOLING SST DUE TO
UPWELLING DURING THE QS STATE WILL SLIGHTLY WEAKEN THE CYCLONE TO
105KTS. AFTERWARD, AS IT BEGINS TO TRACK NORTHWARD, WARM SST AND
INCREASED POLEWARD OUTFLOW WILL FUEL A SECONDARY, ALBEIT WEAK,
INTENSIFICATION, TO 105KTS AT TAUS 72-96. AFTER TAU 96, INCREASING
VWS AND COOLING SST WILL BEGIN TO ERODE THE SYSTEM, DOWN TO 95KTS
AS IT APPROACHES BUSAN, S. KOREA.
MODEL DISCUSSION: THE MAIN PACK OF NUMERICAL MODELS ARE IN VERY
GOOD AGREEMENT ACROSS TRACK. HOWEVER, THERE ARE DIFFERENCES IN
SPEED ALONG TRACK ESPECIALLY ON THE DURATION OF QS STATE. IN VIEW
OF THIS, THERE IS ONLY MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST
THAT IS ADJUSTED JUST TO THE RIGHT OF CONSENSUS TO OFFSET THE TWO
UNLIKELY OUTLIERS - AFUM AND JGSM - THAT BRING THE VORTEX ON A MORE
NORTHWESTWARD TRAJECTORY TOWARD CHINA AFTER THE QS STATE. THE
INTENSITY FORECAST CONFIDENCE IS HIGH TO TAU 72 THEN MEDIUM
AFTERWARD.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: HIGH
   INTENSITY 72-120 HR: MEDIUM//
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