Tropical Storm TEMBIN Advisory 12月25日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 33W (TEMBIN) WARNING NR 17//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 33W (TEMBIN), LOCATED APPROXIMATELY 245 NM EAST-
SOUTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WESTWARD AT 16
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS FLARING DEEP CONVECTION WITH A DENSE OVERCAST CLOUD
SHIELD OBSCURING THE LOW LEVEL CIRCULATION CENTER (LLCC). THE
INITIAL POSITION IS PLACED WITH MODERATE CONFIDENCE BASED ON THE
AFOREMENTIONED OBSCURED LLCC, WITH NO RECENT MICROWAVE IMAGERY
AVAILABLE TO HELP LOCATE THE CENTER. THE MOST RECENT MICROWAVE
IMAGE WAS A 241355Z AMSU-B 89GHZ IMAGE, WHICH REVEALED A VERY
DISTINCT MICROWAVE EYE FEATURE WITH CONVECTIVE BANDING FORMING AN
EYEWALL SURROUNDING A MICROWAVE EYE FEATURE.  UPPER-LEVEL ANALYSIS
INDICATES A WEAKLY SUPPORTIVE ENVIRONMENT CHARACTERIZED BY MODERATE
(20 TO 25 KNOTS) EASTERLY VERTICAL WIND SHEAR (VWS) AND GOOD
POLEWARD AND EQUATORWARD OUTFLOW. THE RELATIVELY HIGH VWS IS NEARLY
IN PHASE WITH THE SHEAR VECTOR, LEADING TO LOWER EFFECTIVE SHEAR.
THE SYSTEM HAS RECENTLY MOVED OVER AN AREA OF LOWER SEA SURFACE
TEMPERATURES (SSTS) NEAR 26 DEC CELSIUS, WHICH REMAIN ENTRENCHED
WESTWARD TO THE VIETNAM COAST. THE INITIAL INTENSITY REMAINS
ASSESSED AT 80 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF
T4.5 (77 KNOTS), A CIMSS 241140Z SATCON ESTIMATE OF 79 KNOTS, AND
AN ADVANCED DVORAK TECHNIQUE (ADT) ESTIMATE OF T4.8 (84 KNOTS). TY
33W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF AN EAST-
WEST ORIENTED SUBTROPICAL RIDGE CENTERED NEAR 20 DEG NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 33W WILL CONTINUE TO TRACK WESTWARD TO WEST-NORTHWESTWARD
UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR THROUGH TAU
72. TY 33W HAS REACHED ITS PEAK INTENSITY AND WILL BEGIN TO RAPIDLY
WEAKEN HEREAFTER, UNDER THE COMBINED INFLUENCE OF INCREASING VWS
AND DECREASING SSTS. THE SYSTEM IS EXPECTED TO MAKE LANDFALL ALONG
THE SOUTHERN COAST OF VIETNAM NEAR TAU 24, AND WILL UNDERGO
ADDITIONAL WEAKENING AS IT INTERACTS WITH TERRAIN. DESPITE RE-
EMERGING OVER THE GULF OF THAILAND BY TAU 36, THE SYSTEM IS
EXPECTED TO CONTINUE WEAKENING AS VWS REMAINS HIGH. TY 33W WILL
BEGIN DISSIPATING AS IT CROSSES THE MALAY PENINSULA NEAR TAU 60 AND
IS EXPECTED TO DISSIPATE BY TAU 72 IN THE EASTERN BAY OF BENGAL.
DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72
WITH A 180NM SPREAD IN MODEL SOLUTIONS AT TAU 72 LEADING TO HIGH
CONFIDENCE IN THE JTWC TRACK FORECAST.//
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