Tropical Storm BOLAVEN Advisory Thu Aug 23

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W (BOLAVEN) WARNING NR 15//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 16W (BOLAVEN), LOCATED APPROXIMATELY 500 NM SOUTHEAST OF
KADENA AB, OKINAWA, JAPAN, HAS TRACKED WEST-NORTHWESTWARD AT 09
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS THE LARGE CENTRAL DENSE OVERCAST (CDO) HAS STARTED TO
FORM A LARGE BANDING FEATURE AROUND THE LOW LEVEL CIRCULATION CENTER
(LLCC) WITH THE CENTER BECOMING LESS CLOUD FILLED. A 230854Z WINDSAT
37H MICROWAVE IMAGE INDICATES THE LLCC UNDER THE CDO HAS A WELL
DEVELOPED EYEWALL STRUCTURE WITH MULTIPLE BANDS OF DEEP CONVECTION
WRAPPING INTO THE LLCC ALONG THE SOUTHEASTERN QUADRANT. THE CURRENT
INTENSITY HAS BEEN MAINTAINED AT 100 KNOTS BASED ON THE WINDSAT
IMAGE EVEN IN LIGHT OF THE RECENT DVORAK ESTIMATES INDICATING A
SLIGHT WEAKENING OVER THE PAST SIX HOURS. UPPER LEVEL ANALYSIS
INDICATES TY 16W IS LOCATED TO THE SOUTHEAST OF A SUBTROPICAL RIDGE
(STR) AXIS IN A REGION OF LOW TO MODERATE VERTICAL WIND SHEAR WITH A
POINT SOURCE ANTICYCLONE LOCATED DIRECTLY OVER THE LLCC. TY 16W
CONTINUES TO TRACK ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP
LAYERED STR TO THE NORTH, ANCHORED JUST EAST OF HONSHU, JAPAN.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 16W WILL CONTINUE TO TRACK ALONG THE PERIMETER OF THE STR
THROUGH TAU 72; HOWEVER, GIVEN THE EXTRAORDINARY SIZE AND MAGNITUDE
OF THE CYCLONE, IT WILL MODIFY THE STR, RESULTING IN A MORE POLEWARD
STORM MOTION. AFTER TAU 48, A MID-LATITUDE TROUGH APPROACHING FROM
MONGOLIA AND TRACKING TOWARD THE YELLOW SEA WILL WEAKEN THE STR
RESULTING IN AN EVEN MORE POLEWARD STORM MOTION. THE SYSTEM WILL
STEADILY INTENSIFY, PEAKING AT 120 KNOTS BY TAU 48 AND PRIOR TO
MAKING LANDFALL INTO OKINAWA.
   C. AFTER TAU 72, TY 16W SHOULD TRACK NORTH-NORTHWESTWARD INTO THE
WEAKNESS CAUSED BY THE PREVIOUSLY MENTIONED TROUGH. TRACK SPEEDS
WILL ACCELERATE DURING THIS TIME AND INTENSITY WILL BE ON THE
DECLINE AS OCEAN PARAMETERS BECOME LESS FAVORABLE. HOWEVER, AN
INCREASE OF POLEWARD OUTFLOW SHOULD BE ABLE TO SLIGHTLY OFFSET THE
COOLER OCEAN TEMPERATURES BUT WILL SEE A QUICK WEAKENING BEYOND TAU
96. EXTRATROPICAL TRANSITION IS EXPECTED TO BEGIN BETWEEN TAU 96 AND
120 AS THE SYSTEM TRACKS INTO THE SOUTHERN YELLOW SEA. OBJECTIVE AID
GUIDANCE IS IN VERY GOOD AGREEMENT THROUGH TAU 120. THERE IS HIGH
CONFIDENCE IN THE TRACK FORECAST.//
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