WDPN31 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (MAYSAK) WARNING NR 31//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 04W (MAYSAK), LOCATED APPROXIMATELY 471 NM EAST OF
MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 09 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY 
DEPICTS PERSISTENT DEEP CONVECTION WITH TIGHTLY-CURVED BANDING 
WRAPPING INTO AN OBSCURED LOW-LEVEL CIRCULATION CENTER. THE CURRENT 
POSITION IS BASED ON THE EIR LOOP AND SATELLITE FIXES FROM PGTW AND 
RJTD WITH GOOD CONFIDENCE. THE INITIAL INTENSITY REMAINS AT 85 KNOTS 
BASED ON AN OVERALL ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM 
ALL REPORTING AGENCIES. 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 VIGOROUS POLEWARD OUTFLOW THAT IS EVIDENT ON 
THE WATER VAPOR IMAGERY. TY MAYSAK IS TRACKING ALONG THE 
SOUTHWESTERN PERIPHERY OF THE DEEP LAYERED SUBTROPICAL RIDGE (STR) 
LOCATED TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 04W WILL CONTINUE TRACKING WEST-NORTHWESTWARD THROUGH TAU 
72 UNDER THE STEERING INFLUENCE OF THE STR. MARGINAL UPPER-LEVEL 
CONDITIONS WILL IMPACT THE SYSTEM PRIOR TO LANDFALL AND WILL FURTHER 
WEAKEN AS TY 04W TRACKS OVER LUZON.
   C. IN THE EXTENDED TAUS, A STRONG NORTHEASTERLY SURGE THROUGH THE 
TAIWAN STRAIT WILL FORCE THE WEAKENED SYSTEM TO BEND WESTWARD. THE 
COMBINED EFFECT OF STRONG VWS AND POOR OUTFLOW ALOFT WILL LEAD TO 
ITS DISSIPATION BY THE END OF THE FORECAST PERIOD. DYNAMIC GUIDANCE 
REMAINS IN GOOD AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC 
FORECAST TRACK.//
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