WDPN35 PGTW 290300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (JONGDARI) WARNING 
NR 29//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 15W (JONGDARI), LOCATED APPROXIMATELY 53 NM
EAST-NORTHEAST OF IWAKUNI, JAPAN, HAS TRACKED WESTWARD AT 23 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MSI SHOWS THE CENTRAL CONVECTION
CONTINUED TO COLLAPSE AND UNRAVEL AS THE SYSTEM TRACKED ACROSS THE
RUGGED TERRAIN OF SOUTHWESTERN HONSHU. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON A COMPOSITE RADAR LOOP FROM KINKI THAT
CLEARLY SHOWS THE LLC WIDENING AND EVENTUALLY OPENING UP ALONG THE
NORTHEAST QUADRANT. THIS POSITION CONFORMS WITH WIND DIRECTIONS FROM
SURROUNDING OBSERVING STATIONS. THE INITIAL INTENSITY OF 40 KNOTS IS
ASSESSED AND EXTRAPOLATED FROM NEARBY WIND AND SURFACE PRESSURE 
OBSERVATIONS. UPPER-LEVEL ANALYSIS INDICATES MODERATE VWS MITIGATED 
BY GOOD POLEWARD OUTFLOW. AN EQUATORWARD OUTFLOW CHANNEL INTO A BROAD 
UPPER LEVEL LOW TO THE SOUTH HAS ALSO OPENED UP. THE CYCLONE IS 
TRACKING ALONG THE SOUTHEAST PERIPHERY OF A BUILDING STR TO THE 
NORTHWEST ANCHORED OVER NORTHEASTERN CHINA.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE. 
   B. TS JONGDARI WILL TRACK GENERALLY SOUTHWESTWARD UNDER THE
INFLUENCE OF THE STR. MODERATE VWS AND THE FRICTIONAL EFFECTS OF THE
RUGGED JAPANESE ISLANDS WILL GRADUALLY ERODE THE SYSTEM. BY TAU 12,
TS 15W WILL BE REDUCED TO 30 KNOTS BEFORE IT EXITS KYUSHU JUST
NORTHEAST OF SASEBO INTO THE EAST CHINA SEA (ECS). THE SYSTEM WILL
ERODE FASTER DUE TO SUBSIDENCE AS IT APPROACHES THE AFOREMENTIONED
UPPER LEVEL LOW, AND BY TAU 36, TS 15W WILL DISSIPATE IN THE ECS AS A
WEAK DISTURBANCE. CONCURRENTLY, THE CYCLONE WILL GET CAUGHT IN A QS
MOTION AS THE UPPER LEVEL LOW NIPS AT THE STEERING STR, DESCEND DOWN
TO THE SURFACE AND INTERACT WITH 15W. BEYOND TAU 36, THERE IS A
POSSIBILITY THAT 15W WILL RE-INTENSIFY AND EVENTUALLY GET CAUGHT IN
THE WESTWARD STEERING FLOW OF THE SAME STR. THE NUMERICAL GUIDANCE
SPREADS OUT FROM TAU 00 AND AFTER TAU 24, THE MODELS GREATLY DIVERGE
IN THEIR TRACK SOLUTIONS. IN VIEW OF THIS, THERE IS LOW CONFIDENCE IN
THE JTWC FORECAST TRACK.//
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