WDPN31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (MAYSAK) WARNING NR 
35//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 04W (MAYSAK), LOCATED APPROXIMATELY 197 NM 
EAST- NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 
08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED IR (EIR) IMAGERY 
SHOWS SOME DEEP CONVECTION WITH CURVED BANDING WRAPPING INTO THE 
OBSCURED LOW-LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS BASED 
ON THE EIR LOOP AND AN EDGE OF SWATH 041246Z GPM WITH LOW 
CONFIDENCE. THE INITIAL INTENSITY HAS BEEN LOWERED TO 60 KNOTS BASED 
ON THE WEAKENING TREND OF THE SYSTEM AND LOW VALUES ASSOCIATED WITH 
A 040927Z RSCAT PARTIAL PASS. UPPER-LEVEL ANALYSIS INDICATES THE 
SYSTEM IS LOCATED IN AN AREA OF LOW TO MODERATE (10 TO 20 KNOT) 
VERTICAL WIND SHEAR (VWS) OFFSET BY RADIAL OUTFLOW AS APPARENT IN 
THE EIR LOOP. TS MAYSAK IS TRACKING ALONG THE SOUTHEASTERN PERIPHERY 
OF THE DEEP LAYERED SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 04W WILL CONTINUE TRACKING NORTHWESTWARD THROUGH TAU 72 
UNDER THE STEERING INFLUENCE OF THE STR, MAKING LANDFALL IN THE 
CENTRAL LUZON JUST BEFORE TAU 12. EXPECT THAT A COMBINATION OF 
INCREASING VWS AND LAND INTERACTION WILL GRADUALLY ERODE THE SYSTEM 
THROUGH TAU 24. HOWEVER, TS 04W WILL EMERGE IN THE SOUTH CHINA SEA 
AS A WEAK TROPICAL STORM AND CONTINUE TO TRACK TO THE NORTHWEST 
THROUGH TAU 72 AS THE STEERING STR TRACKS SLIGHTLY TO THE WEST.
   C. IN THE EXTENDED FORECAST PERIOD, A NORTHEASTERLY COLD SURGE 
EVENT THROUGH THE STRAIGHTS OF TAIWAN WILL AID IN THE CONTINUED 
DISSIPATION OF TS MAYSAK. EXPECT COMPLETE DISSIPATION OF THE STORM 
BY TAU 96. WHILE NUMERICAL MODEL GUIDANCE HAS SPREAD SLIGHTLY OVER 
THE PAST 6 HOURS, THEY REMAIN IN GOOD AGREEMENT, LEADING TO HIGH 
CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS LAID CLOSE TO THE 
MULTI-MODEL CONSENSUS.//
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