Tropical Storm MUIFA Advisory Mo, 12.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (MUIFA) WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 24.2N 124.2E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 239 NM SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TY 14W HAS CONTINUED TO STEADILY WEAKEN AS IT INTERACTS WITH
ISHIGAKI-JIMA AND COMPLETES AN EYEWALL REPLACEMENT CYCLE (ERC).
ADDITIONALLY, THE SYSTEM IS LIKELY UPWELLING COOLER WATER DUE TO
ITS SLOW TRACK MOTION. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY AND RADAR IMAGERY INDICATE A BREAK IN THE EYEWALL OVER THE
NORTHWEST QUADRANT WITH WEAKENING SPIRAL BANDING. AN 112210Z SSMIS
91GHZ MICROWAVE IMAGE INDICATES AN ERC HAS COMPLETED AND SHOWS AN
ERODING INNER EYEWALL AND AN OUTER 60NM DIAMETER EYEWALL. THE CIMSS
M-PERC PRODUCT IS CURRENTLY UNAVAILABLE. RECENT SURFACE OBSERVATIONS
FROM ISHIGAKI-JIMA SHOW MAXIMUM SUSTAINED WINDS OF 51 KNOTS (10-
MINUTE AVERAGE) WITH GUSTS UP TO 73 KNOTS, AND MINIMUM SLP OF 968MB,
WHICH CORRELATES WELL WITH THE MAXIMUM WIND GUSTS. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON EIR IMAGERY AND
HOURLY RJTD RADAR FIXES. THE INITIAL INTENSITY OF 85 KTS IS ASSESSED
WITH MEDIUM CONFIDENCE BASED ON AN AVERAGE OF THE DVORAK CURRENT
INTENSITY ESTIMATES RANGING FROM 77 TO 90 KNOTS. UPPER-LEVEL
CONDITIONS REMAIN FAVORABLE WITH RADIAL OUTFLOW AND LOW VERTICAL WIND
SHEAR.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST WITH A WEAK EXTENSION TO THE EAST
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 90 KTS AT 112330Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: UPWELLING COOL WATER
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: DUE TO THE PRESENCE OF A LARGE MONSOON
DEPRESSION (INVEST 92W) TO THE EAST, THE STR IS WEAK EAST OF THE
SYSTEM, THEREFORE, TY 14W IS TRACKING SLOWLY POLEWARD. THE PRIMARY
STR REMAINS ENTRENCHED TO THE NORTHEAST AND IS CENTERED OVER
WESTERN JAPAN WITH A BROAD 500MB TROUGH POSITIONED OVER EASTERN
CHINA EXTENDING OVER, AND ENVELOPING TY 14W. THE SYSTEM WILL
CONTINUE TO TRACK SLOWLY NORTHWARD TO NORTH-NORTHWESTWARD THROUGH
TAU 72. SLIGHT RE-INTENSIFICATION MAY OCCUR WITHIN THE NEXT 12
HOURS AS THE SYSTEM TRACKS NORTH OF ISHIGAKI-JIMA THEN STEADY
WEAKENING AS THE SYSTEM TRACKS WITHIN THE EASTERN PERIPHERY OF THE
UPPER-LEVEL TROUGH. AFTER TAU 72, TY 14W WILL ACCELERATE AS IT
TRACKS ALONG THE WESTERN PERIPHERY OF THE PRIMARY STR OVER WESTERN
JAPAN. RAPID WEAKENING WILL OCCUR AS THE SYSTEM SKIRTS THE EAST
COAST OF CHINA.
MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, WHICH TRACKS THE
SYSTEM WESTWARD, NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72 WITH A 120NM SPREAD IN SOLUTIONS AT TAU 72. THE
BULK OF THE ECMWF AND GFS ENSEMBLES SUPPORT THE JTWC FORECAST TRACK,
HOWEVER, THERE ARE SOME SOLUTIONS WHICH CURL THE SYSTEM WESTWARD
OVER CHINA. AFTER TAU 72, GUIDANCE DIVERGES WITH INCREASING
UNCERTAINTY IN THE JTWC FORECAST TRACK. A TRACK FURTHER INLAND IS
FEASIBLE AND WILL RESULT IN A FASTER DISSIPATION SCENARIO.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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