Tropical Storm DOLPHIN Advisory 9月24日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (DOLPHIN) WARNING
NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 14W (DOLPHIN), LOCATED APPROXIMATELY 168 NM
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY INDICATES ERODING DEEP CONVECTION SHEARING EASTWARD DUE TO
STRONG (40KTS+) WESTERLY VERTICAL WIND SHEAR (VWS), PARTLY EXPOSING A
RAGGED AND ELONGATED LOW LEVEL CIRCULATION (LLC). THIS IS CORROBORATED
BY A 231629Z AMSR MICROWAVE PASS. THE EIR LOOP ALSO INDICATES THE
FORMATION OF A FRONTAL BOUNDARY ALONG THE NORTHEAST PERIPHERY. THE
INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE PARTLY
EXPOSED LLC IN THE EIR AND MICROWAVE IMAGES. THE INITIAL INTENSITY OF
45KTS IS BASED ON OVERALL ASSESSMENT OF AGENCY AND OBJECTIVE DVORAK
ESTIMATES RANGING FROM T2.5/35KTS TO T3.5/55KTS AND REFLECTS THE
DEGRADED STATUS OF THE SYSTEM. ANALYSES INDICATE THIS ASYMMETRIC HYBRID
(SUBTROPICAL) SYSTEM IS EMBEDDED WITHIN THE PREVAILING WESTERLIES WITH
INCREASING BAROCLINICITY. HOWEVER, THE SYSTEM HAS MAINTAINED A GOOD
POLEWARD OUTFLOW CHANNEL AND WARM (28C) SST VALUES TO PARTIALLY OFFSET
THE STRONG VWS. TS 14W IS TRACKING ALONG THE NORTHWESTERN PERIPHERY OF
THE SUBTROPICAL RIDGE (STR) TO THE EAST-SOUTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS DOLPHIN WILL CONTINUE ON ITS CURRENT TRACK UNDER THE STEERING
STR. AFTER TAU 12, IT WILL TURN MORE POLEWARD AS THE STR BUILDS AND
REORIENTS. INCREASING VWS WILL OFFSET THE STRONG POLEWARD OUTFLOW AND
WARM SSTS AND GRADUALLY WEAKEN THE SYSTEM DOWN TO 35KTS BY TAU 24.
CONCURRENTLY, TS 14W HAS BEGUN EXTRA-TROPICAL TRANSITION AND BY TAU 24,
WILL TRANSFORM INTO A STORM-FORCE COLD CORE LOW WITH FRONTAL
CHARACTERISTICS DEEP IN THE BAROCLINIC ZONE. NUMERICAL MODELS ARE IN
TIGHT AGREEMENT THROUGH THE FORECAST PERIOD WITH AFUM AND ECMWF AS
LEFT-OF-TRACK OUTLIERS. THERE IS HIGH CONFIDENCE IN THE JTWC TRACK
FORECAST THAT IS LAID JUST RIGHT OF CONSENSUS TO OFFSET THE MODEL
OUTLIERS.//
NNNN
NNNN