Tropical Storm HINNAMNOR Advisory Mo, 29.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (HINNAMNOR) WARNING
NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 27.3N 145.3E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 937 NM EAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A COMPACT,
SYMMETRICAL SYSTEM WITH SPIRAL BANDING FROM THE NORTHERN PERIPHERY
THAT HAS WRAPPED TIGHTER INTO AN OBSCURED LOW LEVEL CIRCULATION
CENTER (LLCC). THE CENTRAL DENSE OVERCAST FEATURE, WHICH IS OBSCURING
THE LLCC HAS A FORMATIVE EYE NEAR THE CENTER. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON A DEFINED EYE FEATURE IN
THE 2313Z GPM 37GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY OF 55KTS
IS ALSO ASSESSED WITH HIGH CONFIDENCE BASED ON AGENCY AND AUTOMATED
DVORAK ESTIMATES THAT REFLECT THE 6-HR STRUCTURAL IMPROVEMENT AND
CONSISTENT WITH A FORMATIVE EYE. THE ENVIRONMENT REMAINS FAVORABLE
WITH STRONG EQUATORWARD OUTFLOW, MODERATE VERTICAL WIND SHEAR, AND
WARM SSTS.
INITIAL WIND RADII BASIS: PERSISTENCE.
CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
EXTENSION TO THE NORTH.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 53 KTS AT 282208Z
   CIMSS ADT: 53 KTS AT 282340Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG EQUATORWARD
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: S HINNAMNOR WILL TRACK GENERALLY WESTWARD TOWARD
OKINAWA UNDER THE STEERING STR. AFTER TAU 72, A SECONDARY STR OVER
CENTRAL CHINA, EMERGING BEHIND A TRANSITORY SHORTWAVE TROUGH, AND A
NEAR EQUATORIAL RIDGE TO THE SOUTHEAST WILL COMPETE FOR STEERING,
FORCING THE SYSTEM TO BECOME QUASI-STATIONARY (QS) IN A COL AREA. THE
AFOREMENTIONED FAVORABLE CONDITIONS WILL PROMOTE GRADUAL THEN RAPID
INTENSIFICATION TO A PEAK OF 130KTS BY TAU 72. AFTERWARD, COOLING SST
DUE TO UPWELLING INDUCED BY THE SYSTEM BEING QS IN THE COL WILL
WEAKEN THE SYSTEM TO 105KTS BY TAU 100.
MODEL DISCUSSION: THE MAJORITY OF AVAILABLE NUMERICAL MODELS IS IN
BROAD AGREEMENT UP TO TAU 72. AFTERWARD, TWO MODELS - NVGM AND
UKMET - RECURVE THE VORTEX TOWARD JAPAN IN RESPONSE TO THE TRANSITORY
SHORTWAVE TROUGH. THE MAIN PACK CONTINUES WESTWARD TOWARD THE COL
AREA. IN VIEW OF THIS, AND GIVEN THE UNCERTAINTIES IN TRACK MOTION
INHERENT IN A COL, THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK, LAID
NEAR THE CONSENSUS OF THE MAIN PACK, AND INTENSITY FORECASTS UP TO
TAU 72 THEN LOW CONFIDENCE AFTERWARD.
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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