Tropical Storm BOLAVEN Advisory Tue Jan 02

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING
NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 01W (ONE), LOCATED APPROXIMATELY 318 NM
SOUTH OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 18 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
A PARTIALLY-EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH DEEP
CONVECTION SHEARED OVER THE WESTERN SEMI-CIRCLE DUE TO MODERATE (15
TO 20 KNOTS) EASTERLY VERTICAL WIND SHEAR (VWS). A 020600Z HIMAWARI
VISIBLE SATELLITE IMAGE SHOWS THE AFOREMENTIONED PARTIALLY-EXPOSED
LLCC WITH THE MAJORITY OF THE CONVECTION SHEARED TO THE WEST. THE
INITIAL INTENSITY IS ASSESSED AT 30 KNOTS, HEDGED SLIGHTLY ABOVE THE
RJTD DVORAK ESTIMATE OF T1.5 (25 KNOTS). TD 01W IS TRACKING WESTWARD
ACROSS THE SULU SEA UNDER THE STEERING INFLUENCE OF AN EAST-WEST
ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 01W IS FORECAST TO CONTINUE TRACKING WESTWARD UNDER THE
INFLUENCE OF THE STR WHICH IS LOCATED TO THE NORTH AND GRADUALLY
INCREASE IN INTENSITY TO 35 KNOTS BY TAU 12. MODERATE VERTICAL WIND
SHEAR WILL PREVENT ADDITIONAL INTENSIFICATION. AS TD 01W ENTERS THE
SOUTH CHINA SEA IT WILL INITIALLY ENCOUNTER FAVORABLE SEA SURFACE
TEMPERATURES (28 TO 29 DEGREES CELSIUS). HOWEVER, AS TD 01W TRACKS
WESTWARD IT WILL ENCOUNTER COOLER SEA SURFACE TEMPERATURES WHICH
WILL LIMIT DEVELOPMENT. SEA SURFACE TEMPERATURES WILL BECOME
UNFAVORABLE (25 DEGREES CELSIUS) BY TAU 48. SHORTLY AFTER TAU 48 TD
01W WILL MAKE LANDFALL OVER SOUTHERN VIETNAM AND SLOW IN FORWARD
SPEED. BY TAU 72, TD WILL DISSIPATE OVER VIETNAM DUE TO LAND
INTERACTION. NUMERICAL MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT
THROUGH TAU 24. BEYOND TAU 24, THERE IS A LARGE SPREAD IN THE MODEL
GUIDANCE AS TD 01W APPROACHES VIETNAM. OVERALL, THERE IS LOW
CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO THE LARGE SPREAD IN
MODEL SOLUTIONS AFTER TAU 24.//
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