WDPN32 PGTW 242100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (MOLAVE) WARNING 
NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 21W (MOLAVE), LOCATED APPROXIMATELY 401
NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 11 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH IMPROVED CONVECTIVE 
BANDING WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC). A 
242011Z SSMIS 91GHZ MICROWAVE IMAGE INDICATES TIGHTLY-CURVED BANDING 
WRAPPING INTO THE LLCC, WHICH SUPPORTS THE INITIAL POSITION WITH 
GOOD CONFIDENCE; THE 37GHZ IMAGE DEPICTS A SMALL MICROWAVE EYE 
FEATURE, WHICH TYPICALLY SIGNALS RAPID INTENSIFICATION ONSET. THE 
INITIAL INTENSITY REMAINS ASSESSED AT 35 KNOTS BASED ON THE HIGHER 
END OF DVORAK INTENSITY ESTIMATES RANGING FROM T2.0-2.5 (30-35 
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 CONSOLIDATING AS IT TRACKS 
GENERALLY WESTWARD ALONG THE PERIPHERY OF THE STR. AS FAVORABLE 
CONDITIONS PERSIST, THE SYSTEM SHOULD INTENSIFY TO 60 KTS PRIOR TO 
MAKING LANDFALL OVER THE EASTERN PHILIPPINES NEAR TAU 18. AS IT 
TRANSITS OVER THE ARCHIPELAGO, THE SYSTEM SHOULD MAINTAIN INTENSITY 
(OR POSSIBLY WEAKEN SLIGHTLY) BEFORE THE SYSTEM RE-EMERGES OVER THE 
SOUTH CHINA SEA WHERE IT IS EXPECTED TO RE-INTENSIFY TO A PEAK OF 80 
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 AS THE SYSTEM 
APPROACHES CENTRAL VIETNAM WITH A 135NM SPREAD IN SOLUTIONS NEAR THE 
LANDFALL POINT. TS 21W WILL WEAKEN 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 MODEL SPREAD IN THE LATER TAUS, THERE IS 
OVERALL FAIR CONFIDENCE IN THE JTWC FORECAST TRACK.//
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