Tropical Storm CHOI-WAN Advisory 6月5日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (CHOI-WAN)
WARNING NR 025//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 04W (CHOI-WAN), LOCATED APPROXIMATELY 353 NM
SOUTHWEST OF KADENA AB, HAS TRACKED NORTHEASTWARD AT 16 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS POCKETS OF WEAK CONVECTION AND MID LEVEL CLOUD LINES
OBSCURING THE LOW LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS
PLACED WITH FAIR CONFIDENCE BASED ON THE ANALYSIS OF THE MID LEVEL
CONVECTIVE FEATURES IN THE ANIMATED EIR AND COMPOSITE RADAR LOOPS.
THE INITIAL INTENSITY OF 30 KTS IS PLACED WITH FAIR CONFIDENCE AND
IS HEDGED BETWEEN MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATE OF
T1.0 (25 KTS, PGTW) AND T2.0 (30 KTS, RJTD), AN ADVANCED DVORAK
TECHNIQUE INTENSITY ESTIMATE OF T1.5 (25 KTS) AND A 041329Z CIMSS
SATELLITE CONSENSUS INTENSITY ESTIMATE OF 43 KTS. IN ADDITION, A
SHIP OBSERVATION IN THE VACINITY OF THE SYSTEM REPORTED 31 KTS WINDS
ALONG THE SOUTHEAST PERIPHERY OF THE SYSTEM. TD CHOI-WAN IS TRACKING
ALONG THE NORTHWESTERN PERIPHERY OF A SUB-TROPICAL RIDGE (STR)
POSITIONED TO THE SOUTHEAST AND THROUGH A MARGINALLY FAVORABLE
ENVIRONMENT WITH WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURE VALUES
AND LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS) OFFSET BY CONVERGENT
AND ROBUST WESTERLY FLOW IN THE UPPER LEVELS.
   A. THE FORECAST PHILOSOPHY HAS BEEN UPDATED TO REFLECT DISSIPATION
AT TAU 36, RATHER THAN EXTRATROPICAL TRANSITION.
   B. TD CHOI-WAN WILL CONTINUE TO TRACK GENERALLY NORTHEASTWARD
TOWARDS THE MEI-YU BOUNDARY POSITIONED NORTHWEST OF THE RYUKYU
ISLANDS. AS THE SYSTEM APPROACHES THE BOUNDARY IT WILL BRIEFLY
INTENSIFY TO 40 KTS BY TAU 12 DUE TO THE ADDED VORTICITY IMPARTED BY
THE NORTHEASTERLY FLOW ALONG THE WESTERN PERIPHERY OF THE SHEAR
LINE. THEREAFTER, VWS INCREASE DRAMATICALLY TO 40+ KTS. THIS
INCREASED VWS, COUPLED WITH COOLING SST VALUES, WILL LEAD TO
WEAKENING AFTER TAU 12 AND LEAD TO DISSIPATION OVER WATER BY TAU 36
AT WHICH TIME THE SYSTEM WILL BECOME EMBEDDED IN THE MEI-YU
BOUNDARY. NUMERICAL MODEL SOLUTIONS ARE IN GOOD AGREEMENT REGARDING
STORM TRACK AND INTENSITY WITH THE MAJORITY OF DYNAMICAL MODELS
AGREEING ON THE BRIEF INTENSIFICATION SCENARIO AT TAU 12. THIS HIGH
DEGREE OF AGREEMENT IN MODEL SOLUTIONS LENDS OVERALL HIGH CONFIDENCE
IN THE JTWC FORECAST TRACK, WHICH IS PLACED ALONG THE MULTI-MODEL
CONSENSUS.//
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