WDPN31 PGTW 090300 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION (TD) 03W WARNING 
NR 9//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 090000Z9 TO 120000Z3 MAY 01.
   A. TROPICAL DEPRESSION (TD) 03W, LOCATED APPROXIMATELY 180 NM 
SOUTH OF MANILA, HAS TRACKED WESTWARD AT 11 KNOTS OVER THE PAST SIX 
HOURS. THE WARNING POSITION IS BASED ON 082330Z6 VISIBLE AND 
INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON 
SATELLITE CURRENT INTENSITY ESTIMATES OF 25 KNOTS. ANIMATED VISIBLE 
AND INFRARED SATELLITE IMAGERY INDICATES THE SYSTEM HAS BECOME MORE 
ORGANIZED OVER THE PAST 6 HOURS AS IT BEGINS TO MOVE WEST OF THE 
PHILIPPINE ISLANDS. UW-CIMSS UPPER LEVEL WIND ANALYSIS INDICATES 
FAVORABLE CONDITIONS ALOFT WITH DECREASING SHEAR OVER THE PAST 6 
HOURS. UPPER LEVEL ANALYSIS INDICATES AN ANTICYCLONE IS DEVELOPING 
OVER THE SYSTEM, PROVIDING GOOD OUTFLOW AND DIFFLUENCE.
   B. TD 03W IS FORECAST TO TRACK NORTHWESTWARD THROUGH THE 36 HOUR 
PERIOD UNDER THE STEERING INFLUENCE OF THE LOW TO MID-LEVEL RIDGE TO 
THE NORTHEAST. AN APPROACHING MID-LATITUDE TROUGH IS EXPECTED TO 
CREATE A WEAKNESS IN THE RIDGE AND THUS ALLOW THE SYSTEM TO TRACK 
MORE NORTHERLY AFTER 36 HOURS. THE AVAILABLE FORECAST AIDS ARE IN 
FAIR AGREEMENT. THE NAVY OPERATIONAL GLOBAL ATMOSPHERIC PREDICTION 
SYSTEM (NOGAPS) AND THE GEOPHYSICAL FLUID DYNAMICS NAVY (GFDN) MODEL 
TRACKS THE SYSTEM TO THE NORTHWEST THROUGH 48 HOURS AND THEN 
INCREASINGLY NORTHWARD. THE UK-MET OFFICE (EGRR) MODEL 
ALSO TRACKS THE SYSTEM NORTHWESTWARD THROUGH 48 HOURS. AFTER THIS 
TIME EGRR TRACKS THE SYSTEM SOUTHWESTWARD DUE TO INTERACTION WITH A 
SECONDARY LOW LOCATED SOUTHWEST OF THE SYSTEM. THE OFFICIAL FORECAST 
IS BASED ON THE DYNAMIC AID CONSENSUS AND FAVORS THE NOGAPS AND GFDN 
TRACKS. THE NUMERICAL CONSENSUS CONSISTS OF THREE DYNAMIC MODELS 
(NOGAPS, GFDN, AND EGRR).      
   C. THE SYSTEM IS FORECAST TO MAINTAIN TROPICAL DEPRESSION 
STRENGTH AS LAND TOPOGRAPHY CONTINUES TO INTERFERE WITH LOW LEVEL 
INFLOW. THE SYSTEM IS EXPECTED TO SLOWLY INTENSIFY AFTER 24 HOURS AS 
IT MOVES INTO THE SOUTH CHINA SEA. 
   D. WIND RADII FOR THE 48 AND 72 HOUR FORECAST ARE BASED ON 
CLIMATOLOGY FOR AN AVERAGED SIZE STORM.
FORECAST TEAM: CANTRELL/WHITCOMB//



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