Tropical Storm USAGI Advisory Wed Nov 21

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 33W (THIRTYTHREE)
WARNING NR 13//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 33W (THIRTYTHREE), LOCATED APPROXIMATELY 215
NM SOUTH-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-
SOUTHWESTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) SUGGESTS THE POORLY-DEFINED
LOW LEVEL CIRCULATION CENTER (LLCC) HAS BECOME CLOSER TO SOME
CONVECTION. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED
ON THE ANIMATED MSI. THE INITIAL INTENSITY IS ASSESSED AT 25 KNOTS,
BASED ON A DVORAK CURRENT INTENSITY ESTIMATE OF T1.5(25 KNOTS) FROM
RJTD. THE ENVIRONMENT IS MARGINAL FOR INTENSIFICATION WITH GOOD
POLEWARD OUTFLOW AND WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURE
(SST) BEING OFFSET BY MODERATE (20-25 KNOT) VERTICAL WIND SHEAR
(VWS) AND LINGERING TERRAIN EFFECTS. TD 33W IS TRACKING ALONG THE
SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A.  THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 72, TD 33W IS FORECAST TO CONTINUE TRACKING
GENERALLY WESTWARD UNDER THE INFLUENCE OF THE STR. THE SYSTEM WILL
CONTINUE TO STRUGGLE CONSOLIDATING UNTIL OVER THE SOUTH CHINA SEA.
ONCE THERE, TD 33W IS EXPECTED TO INTENSIFY TO 55 KNOTS BY TAU 72 AS
THE OVERALL ENVIRONMENT BECOMES MORE FAVORABLE WITH LOW VWS AND
IMPROVED UPPER LEVEL OUTFLOW. SPREAD IN NUMERICAL MODEL GUIDANCE IS
PRETTY HIGH WHILE THE SYSTEM MOVES THROUGH THE PHILIPPINES AND IS
ILL-DEFINED, HOWEVER, THEY ALL SHOW A SIMILAR WESTWARD TRACK THROUGH
TAU 72. THE JTWC TRACK FORECAST IS PLACED CLOSE TO CONSENSUS WITH
FAIR CONFIDENCE THROUGH TAU 72.
   C. AFTER TAU 72, TD 33W IS EXPECTED TO MAKE A SLOW TURN POLEWARD
AROUND THE WESTERN PERIPHERY OF THE STR AND MAKE LANDFALL ALONG THE
CENTRAL VIETNAM COASTLINE NEAR TAU 80. AFTER MAKING LANDFALL, TD 33W
WILL CONTINUE TRACKING NORTH-NORTHWESTWARD AND BEGIN DISSIPATING DUE
TO LAND INTERACTION. SPREAD IN THE NUMERICAL MODEL GUIDANCE GROWS
SIGNIFICANTLY AS THE SYSTEM ROUNDS THE STR AXIS. THE OFFICIAL JTWC
TRACK FORECAST IS PLACED JUST RIGHT OF THE CONSENSUS TRACK AND,
BASED ON THE HIGH SPREAD, CONFIDENCE IS LOW.//
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