Tropical Storm BAVI Advisory 8月25日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 09W (BAVI), LOCATED APPROXIMATELY 290 NM SOUTH-
SOUTHWEST OF KUNSAN AB, SOUTH KOREA, HAS TRACKED NORTH-
NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY DEPICTS GRADUAL WEAKENING OF THE OUTER
SPIRAL BANDING, HOWEVER, THE SYSTEM RETAINS A COMPACT EYEWALL
SURROUNDING A SMALL 10NM EYE, WHICH SUPPORTS THE INITIAL POSITION
WITH HIGH CONFIDENCE. A 251700Z AMSR2 89GHZ COMPOSITE IMAGE
INDICATES AN EYEWALL REPLACEMENT CYCLE (ERC) WITH THE INNER EYEWALL
BEGINNING TO ERODE AND AN OUTER EYEWALL FORMING. THE UW-CIMSS M-PERC
PRODUCT ALSO DEPICTS THE TWO EYEWALLS, HOWEVER, THE PROBABILITIES
REMAIN LOW AT ABOUT 10%. THE INITIAL WIND RADII HAVE BEEN ADJUSTED
BASED ON A DETAILED ANALYSIS OF THE 251134Z ASCAT-A IMAGE. UPPER-
LEVEL CONDITIONS ARE FAVORABLE FOR DEVELOPMENT WITH ROBUST POLEWARD
OUTFLOW AND LOW TO MODERATE VERTICAL WIND SHEAR (VWS). SST VALUES
(29 TO 30C) REMAIN CONDUCIVE. THE INITIAL INTENSITY REMAINS
ASSSESSED AT 95 KNOTS BASED ON AN AVERAGE OF SUBJECTIVE DVORAK
INTENSITY ESTIMATES OF T5.0 (90 KNOTS) AND A 251800Z ADT ESTIMATE OF
5.3/5.7 (ROUGHLY 95 TO 105 KNOTS). TY 09W IS TRACKING POLEWARD ALONG
THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 09W WILL CONTINUE TO TRACK POLEWARD OVER THE NEXT 48
HOURS ALONG THE WESTERN PERIPHERY OF THE BUILDING STR TO THE EAST.
WITH THE EXCEPTION OF THE SOLE OUTLIER AFUI, NUMERICAL MODEL
GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 36 WITH A 47NM SPREAD IN
SOLUTIONS AT TAU 36. ADDITIONALLY, THE ECMWF ENSEMBLE SOLUTIONS ARE
ALSO IN GOOD AGREEMENT REFLECTING A HIGH CONFIDENCE (LOW
UNCERTAINTY) FORECAST TRACK. THERE IS SOME POTENTIAL FOR SLIGHT
INTENSIFICATION OVER THE NEXT 12 HOURS AS THE ERC COMPLETES AND THE
OUTER EYEWALL CONTRACTS. NEAR TAU 24, THE SYSTEM WILL BEGIN EXTRA-
TROPICAL TRANSITION AS IT INTERACTS THE MIDLATITUDE SOUTHWESTERLY
FLOW. TY 09W WILL GRADUALLY WEAKEN AS THE SYSTEM ENCOUNTERS COOLER
SST (28-25C) OVER THE NORTHERN YELLOW SEA AND STRONG VWS AFTER TAU
24. TY 09W SHOULD COMPLETE EXTRA-TROPICAL TRANSITION BY TAU 48 AS IT
GAINS FRONTAL CHARACTERISTICS AND NEARS THE JET. OVERALL, THERE IS
HIGH CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS POSITIONED NEAR
THE MULTI-MODEL CONSENSUS.//
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