Tropical Storm KAI-TAK Advisory 12月19日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 32W (KAI-TAK)
WARNING NR 20//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 32W (KAI-TAK), LOCATED APPROXIMATELY 591 NM
EAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WESTWARD AT 13 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS
FLARING CONVECTION LOCATED TO THE NORTHWEST OF THE LOW LEVEL
CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS BASED ON AN
181800Z HIMAWARI INFRARED SATELLITE IMAGE SHOWING CONVECTION
SHEARED TO THE NORTHWEST OF THE LLCC. THE INITIAL INTENSITY
ESTIMATE IS 35 KNOTS WHICH IS BASED ON AN 181420Z ASCAT METOP-B
IMAGE WHICH SHOWS THE WESTERN EXTENT OF THE TS 32W WIND FIELD.
UPPER LEVEL ANALYSIS SHOWS MODERATE VERTICAL WIND SHEAR (20 TO 25
KNOTS) WHICH IS OFFSET BY GOOD POLEWARD OUTFLOW. SEA SURFACE
TEMPERATURES REMAIN FAVORABLE (26 TO 27 DEGREES CELSIUS). TS 32W
TRACKING WESTWARD UNDER THE INFLUENCE OF A SUBTROPICAL RIDGE (STR)
WHICH IS LOCATED TO THE NORTH.
3. FORECAST REASONING.
   A. AVAILABLE METEOROLOGICAL DATA SUPPORTS THE REGENERATION OF TS
32W AT THIS TIME. THIS MESSAGE ESTABLISHES THE FORECAST REASONING
FOR THE REGENERATED SYSTEM.
   B. TS 32W WILL TRACK SOUTHWESTERLY FOR THE REMAINDER OF THE
FORECAST WHILE UNDER THE INFLUENCE OF THE BUILDING STR LOCATED TO
THE NORTHWEST. THE SOUTH CHINA SEA IS EXPERIENCING STRONG NORTHERLY
WINDS WHICH ARE ASSOCIATED WITH A SURGE EVENT. THE DIFFERENTIATION
BETWEEN THE SURGE WINDS AND THE OUTER EDGE OF TS 32W IS DIFFICULT
TO DETERMINE. REGARDLESS, IN THE VICINITY OF TS 32W THE SOUTH CHINA
SEA WILL CONTINUE TO EXPERIENCE WINDS NEAR 35 KNOTS ASSOCIATED WITH
BOTH THE SURGE EVENT AND TS 32W. NUMERICAL MODEL GUIDANCE IS
INDICATING THAT A WARM CORE CIRCULATION WILL MAINTAIN COHESION AS
IT TRACKS SOUTHWESTERLY ACROSS THE SOUTH CHINA SEA. INTENSITY WILL
REMAIN AT 35 KNOTS THROUGH TAU 36 BEFORE BRIEFLY PEAKING AT 40
KNOTS AT TAU 48. TS 32W WILL THEN DECREASE IN INTENSITY.
   C. BEYOND TAU 72, TS 32W WILL CONTINUE TO TRACK SOUTHWESTWARD
UNDER THE INFLUENCE OF THE STR LOCATED TO THE NORTHWEST. VERTICAL
WIND SHEAR IS FORECAST TO INTENSIFY AND WEAKEN TS 32W AS IT TRACKS
ACROSS THE SOUTH CHINA SEA. THE WIND FIELD ASSOCIATED WITH TS 32W
WILL DECREASE IN SIZE BUT THE SURGE EVENT WILL CONTINUE TO PRODUCE
STRONG NORTHERLY WINDS. DYNAMIC MODEL GUIDANCE IS IN RELATIVELY
GOOD AGREEMENT ON TRACK MOTION. HOWEVER, MODELS ARE STILL UNABLE TO
DIFFERENTIATE THE SURGE EVENT WIND FIELD FROM THE TS 32W WIND
FIELD. DESPITE THESE DIFFERENCES THERE IS OVERALL HIGH CONFIDENCE
IN THE FORECAST TRACK.//
NNNN
NNNN