Tropical Storm THIRTYSIX Advisory Mon Dec 31

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 36W (THIRTYSIX)
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 36W (THIRTYSIX), LOCATED APPROXIMATELY
325 NM SOUTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED
WEST-SOUTHWESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM CONTINUED
TO CONSOLIDATE. THE CENTRAL CONVECTION, ALTHOUGH SHEARED
NORTHWESTWARD OF THE LOW LEVEL CIRCULATION (LLC), HAS DEEPENED. THE
INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE EIR LOOP
AND LINED UP TO A NOTCH FEATURE IN THE 311057Z SSMIS MICROWAVE IMAGE.
THE INITIAL INTENSITY OF 30 KNOTS IS BASED ON THE DVORAK ESTIMATE OF
T2.0/30KTS FROM PGTW. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN
AN AREA OF MODERATE (20-25 KNOTS) SOUTHEASTERLY VERTICAL WIND SHEAR
(VWS) OFFSET BY EXCELLENT POLEWARD OUTFLOW. SEA SURFACE TEMPERATURES
IN THE SOUTH CHINA SEA AND INTO THE GULF OF THAILAND ARE VERY
CONDUCIVE AT 28-29 CELSIUS. THE CYCLONE IS TRACKING ALONG THE
SOUTHEASTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) ANCHORED TO THE
NORTHWEST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY  FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 36W IS EXPECTED TO TRACK WEST-SOUTHWESTWARD THEN
NORTHWESTWARD
TOWARD THE GULF OF THAILAND AROUND THE SOUTHERN PERIPHERY OF THE STR.
THE VWS IS EXPECTED TO DECREASE AND ALLOW A MODEST INTENSIFICATION TO
A PEAK OF 45 KNOTS BY TAU 72 AS IT ENTERS THE GULF OF THAILAND.
   C. AFTER TAU 72, VWS WILL ONCE AGAIN PICK UP. THIS, IN ADDITION TO
LAND INTERACTION AS TD 36W CROSSES THE MALAY PENINSULA AFTER TAU 96
WILL CAUSE A STEADY WEAKENING DOWN TO 30 KNOTS BY TAU 120. THE
AVAILABLE NUMERICAL GUIDANCE IS IN OVERALL AGREEMENT WITH GRADUAL
SPREADING TO OVER 300 NM BY TAU 120 WITH HWRF ON THE LEFT AND NAVGEM
ON THE RIGHT MARGIN OF THE MODEL ENVELOPE. THIS, IN ADDITION TO
THE FORMATIVE NATURE OF THE SYSTEM, LENDS LOW CONFIDENCE TO THE JTWC
TRACK FORECAST.//
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