WDPN32 PGTW 250300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (MOLAVE) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 21W (MOLAVE), LOCATED APPROXIMATELY 317 NM 
EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 14 
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY INDICATES A RAPIDLY CONSOLIDATING SYSTEM WITH TIGHTLY-CURVED 
BANDING WRAPPING INTO A DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). 
A 242228Z SSMIS 91GHZ MICROWAVE IMAGE INDICATES TIGHTLY-CURVED 
BANDING WRAPPING INTO THE LLCC, WHICH SUPPORTS THE INITIAL POSITION 
WITH GOOD CONFIDENCE; THE 37GHZ COLOR IMAGE DEPICTS A CYAN RING 
SURROUNDING A SMALL MICROWAVE EYE FEATURE, WHICH TYPICALLY SIGNALS 
RAPID INTENSIFICATION ONSET. THE INITIAL INTENSITY IS ASSESSED AT 55 
KNOTS BASED ON THE HIGHER END OF DVORAK INTENSITY ESTIMATES RANGING 
FROM T2.5-3.5 (35-55 KNOTS) AND A 25/0040Z ADT ESTIMATE OF 3.4 (53 
KNOTS). UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH 
LOW-MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS), IMPROVING 
POLEWARD OUTFLOW AND GOOD EQUATORWARD OUTFLOW. SST VALUES (30C) AND 
OCEAN HEAT CONTENT VALUES REMAIN VERY CONDUCIVE FOR FURTHER 
DEVELOPMENT. TS 21W IS TRACKING GENERALLY WESTWARD UNDER THE 
STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE 
NORTHEAST WITH AN EXTENSION TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 21W IS EXPECTED TO CONTINUE RAPIDLY INTENSIFYING AS IT 
TRACKS GENERALLY WESTWARD ALONG THE PERIPHERY OF THE STR. AS 
FAVORABLE CONDITIONS PERSIST, THE SYSTEM SHOULD INTENSIFY TO 65 KTS 
PRIOR TO MAKING LANDFALL OVER THE EASTERN PHILIPPINES NEAR TAU 12. 
THERE IS SOME POTENTIAL FOR A HIGHER INTENSITY IF THE SYSTEM FORMS 
AN EYE. AS IT TRANSITS OVER THE INNER SEAS SOUTH OF LUZON, THE 
SYSTEM SHOULD MAINTAIN INTENSITY BEFORE THE SYSTEM RE-EMERGES OVER 
THE SOUTH CHINA SEA WHERE IT IS EXPECTED TO RE-INTENSIFY TO A PEAK 
OF 85 KNOTS BY TAU 72. NUMERICAL GUIDANCE IS IN GOOD AGREEMENT 
THROUGH TAU 72 WITH A 90NM SPREAD IN SOLUTIONS AT TAU 72. 
CONSEQUENTLY, THERE IS NOW HIGH CONFIDENCE IN THIS PHASE OF THE 
FORECAST. 
   C. AFTER TAU 72, NUMERICAL GUIDANCE DIVERGES SLIGHTLY AS THE 
SYSTEM APPROACHES CENTRAL VIETNAM. TS 21W WILL WEAKEN GRADUALLY AS 
IT APPROACHES THE COAST AND BEGINS INTERACTING WITH LAND, AND WILL 
WEAKEN SIGNIFICANTLY AS IT TRACKS INLAND, HOWEVER, THE SYSTEM IS 
EXPECTED TO PRODUCE HEAVY RAINFALL. DUE TO THE TIGHTER AGREEMENT 
BETWEEN THE MODELS, THERE IS OVERALL HIGH CONFIDENCE IN THE JTWC 
FORECAST TRACK.//
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