Tropical Storm BAVI Advisory sam, 22.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (BAVI) WARNING NR
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 09W (BAVI), LOCATED APPROXIMATELY 331 NM WEST-
SOUTHWEST OF KADENA AB, OKINAWA, HAS TRACKED NORTH-NORTHEASTWARD AT
06 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
IMAGERY AND ANIMATED RADAR IMAGERY REVEAL A PARTIALLY-EXPOSED LOW
LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION OVER THE
EASTERN SEMICIRCLE OF THE SYSTEM. A 212313Z SSMIS 89 GHZ PARTIAL
MICROWAVE IMAGE SHOWS SHALLOW BANDING WRAPPING INTO THE CENTER FROM
THE WEST AND CONFIRMS THE DEEP CONVECTION TO THE SOUTH AND EAST. SET
AT 35 KTS, THE INITIAL INTENSITY IS BASED ON A SATELLITE CONSENSUS
ESTIMATE OF 34 KTS AND MULTI-AGENCY DVORAK CURRENT INTENSITY
ESTIMATES OF T1.5-T2.0 (25-30 KTS) BY PGTW, RJTD, AND KNES.
FURTHERMORE, A 220055Z PARTIAL ASCAT-B IMAGE DEPICTS A SWATH OF 35-
39 KT WINDS SURROUNDED BY 30-34 KT WINDS IN THE EASTERN QUADRANT,
PLACING GOOD CONFIDENCE IN THE INITIAL INTENSITY. TS 09W REMAINS IN
A HIGHLY FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW (10-15 KTS)
VERTICAL WIND SHEAR, WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES,
AND HIGH OCEAN HEAT CONTENT VALUES. ADDITIONALLY, THE SYSTEM IS
SUPPORTED BY EXCELLENT EQUATORWARD OUTFLOW AND DEVELOPING POLEWARD
OUTFLOW WHICH IS BEING ENHANCED BY AN UPPER LOW TO THE NORTHEAST. A
SUBTROPICAL RIDGE (STR) TO THE EAST WITH A SLIGHT WEAK EXTENSION TO
THE NORTH IS ACTING AS THE PRIMARY STEERING FEATURE. CURRENTLY, TS
09W IS TRACKING NORTH-NORTHWESTWARD ALONG ITS PERIPHERY.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. AS A PASSING SHORTWAVE TROUGH DIGS OVER THE EAST CHINA SEA,
THE WEAK STR EXTENSION IS EXPECTED TO ERODE WHICH WILL CAUSE THE STR
TO REORIENT. BY TAU 24, TS 09W IS FORECAST TO TURN NORTHEASTWARD AND
TRACK ALONG THE PERIPHERY OF THE REORIENTED STR. THE FAVORABLE
ENVIRONMENT WILL CONTINUE TO INTENSIFY THE SYSTEM THROUGHOUT THIS
PERIOD. AFTER TAU 48, TS 09W IS EXPECTED TO SLOW AS IT TURNS TO
NORTHWARD FOLLOWING TROUGH PASSAGE. THE TROUGH PASSAGE IS EXPECTED
TO ENHANCE POLEWARD OUTFLOW, ALLOWING THE SYSTEM TO INTENSIFY TO 95
KTS BY TAU 72. DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT,
GRADUALLY INCREASING TO A SPREAD OF 150 NM BY TAU 72 AS THE SYSTEM
RECURVES TO THE NORTH.
   C. IN THE EXTENDED FORECAST, A STR WILL BUILD OVER WESTERN JAPAN
AFTER THE TROUGH PROPAGATES EASTWARD. AT THIS POINT, TS 09W WILL
TURN NORTHWARD ALONG THE WESTERN PERIPHERY OF THE STR UNTIL LANDFALL
IN SOUTH KOREA AFTER TAU 96. A FAVORABLE ENVIRONMENT WILL ALLOW TS
09W TO INTENSIFY TO A PEAK OF 105 KTS BY TAU 96. AFTERWARDS,
DEGRADING ENVIRONMENTAL CONDITIONS OF INCREASING VERTICAL WIND SHEAR
AND INTERACTION WITH THE KOREAN PENINSULA WILL WEAKEN THE SYSTEM,
FIRST GRADUALLY AND THEN RAPIDLY. A 140 NM SPREAD IN MODELS AT TAU
96 LENDS UNCERTAINTY TO THE LANDFALL LOCATION. HOWEVER, THE
NUMERICAL MODELS ARE IN OVERALL FAIR AGREEMENT, LENDING MODERATE
CONFIDENCE TO THE JTWC FORECAST TRACK.//
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