Tropical Storm FAXAI Advisory 9月5日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (FAXAI) WARNING NR
017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 14W (FAXAI), LOCATED APPROXIMATELY 682 NM
EAST-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 10
KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY SHOWS A PARTLY EXPOSED LOW LEVEL CIRCULATION (LLC)
WITH THE ASSOCIATED DEEP CONVECTION OFFSET TO THE EAST. THE INITIAL
POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE EIR LOOP. THE
INITIAL INTENSITY OF 40KTS IS BASED ON THE HIGH END OF AGENCY AND
OBJECTIVE DVORAK ESTIMATES OF T2.5-T2.7 AND REFLECTS THE SUSTAINED
EIR SIGNATURE. UPPER-LEVEL ANALYSIS MAINTAINS A TUTT CELL TO THE
NORTHWEST AND TROUGHING SOUTHWARD OF IT IS CAUSING STRONG SUBSIDENCE
ALONG THE WESTERN PERIPHERY OF THE CYCLONE, CONSEQUENTLY RESTRICTING
WESTWARD OUTFLOW AND INHIBITING VERTICAL DEVELOPMENT. HOWEVER,
MODERATE SOUTHEASTWARD OUTFLOW INTO ANOTHER TUTT CELL TO THE
EAST PROVIDES VENTILATION TO THE OFFSET CONVECTION. TS 14W HAS A
FAVORABLE VERTICAL WIND SHEAR (VWS) ENVIRONMENT WITH VALUES OF
5-15KTS. TS 14W CONTINUES TO TRACK OVER WARM SST (30C) WHILE A
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST INFLUENCES THE STEERING OF
THE SYSTEM.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 14W WILL CONTINUE ON ITS CURRENT TRACK, STEERED BY THE STR.
AFTER TAU 48, THE TRACK WILL TURN MORE NORTHWARD AS IT BEGINS TO
ROUND THE STR AXIS. BY TAU 72, IT WILL MAKE LANDFALL OVER HONSHU,
JAPAN, NEAR TOKYO. THE OVERALL FAVORABLE ENVIRONMENT WILL PROMOTE
SLOW THEN RAPID INTENSIFICATION TO 80 KTS BY TAU 48 AS POLEWARD
OUTFLOW INCREASES WHILE THE SYSTEM MOVES AWAY FROM THE TUTT CELL
INFLUENCE AND APPROACHES THE PREVAILING WESTERLIES. PEAK INTENSITY
WILL LIKELY BE 90KTS AT TAU 60 AS THE SYSTEM CRESTS THE STR.
AFTERWARD, TY 14W WILL WEAKEN TO 70KTS AFTER LANDFALL.
   C. BEYOND TAU 72, TS FAXAI WILL BEGIN EXTRA-TROPICAL TRANSITION
AND ACCELERATE NORTHEASTWARD BACK INTO THE PACIFIC OCEAN, RAPIDLY
DECAYING DUE TO INCREASING VWS AND COOLER SST, TRANSFORMING INTO A
STRONG GALE-FORCE COLD CORE LOW WITH AN EXPANDING WIND FIELD BY TAU
96 WELL SOUTHEAST OF HOKKAIDO. NUMERICAL MODELS ARE IN TIGHT
AGREEMENT, LENDING HIGH CONFIDENCE IN ALL PORTIONS OF THE JTWC
FORECAST TRACK.//
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