WDPN31 PGTW 021500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (MAYSAK) WARNING NR 27//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 04W (MAYSAK), LOCATED APPROXIMATELY 681 NM EAST OF
MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 08 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY CONTINUES TO DEPICT SIGNIFICANT WEAKENING OF DEEP CONVECTIVE 
STRUCTURE DUE TO MODERATE TO STRONG WESTERLY VERTICAL WIND SHEAR 
(VWS). A 021052Z SSMIS 91 GHZ IMAGE REVEALS EROSION OF DEEP 
CONVECTION OVER THE WESTERN SEMI-CIRCLE WITH THE BULK OF DEEP 
CONVECTION DISPLACED OVER THE NORTHEAST QUADRANT, HOWEVER, THE 
SYSTEM EYEWALL REMAINS INTACT WITH A MICROWAVE EYE FEATURE. 
THEREFORE, THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION AND 
RECENT TRACK MOTION. THE INITIAL INTENSITY OF 105 KNOTS IS BASED ON 
CURRENT INTENSITY ESTIMATES OF T5.5 (105 KNOTS). UPPER-LEVEL 
ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH 20 TO 30 KNOT VWS 
OFFSET BY GOOD POLEWARD OUTFLOW. ADDITIONALLY, SIGNIFICANT DRY AIR 
THROUGH THE MID AND UPPER LEVELS IS IMPEDING FURTHER DEVELOPMENT. TY 
MAYSAK IS TRACKING ALONG THE SOUTHWESTERN 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. TY 04W WILL CONTINUE TRACKING WEST-NORTHWESTWARD UNDER THE 
INFLUENCE OF THE STEERING STR THROUGHOUT THE FORECAST PERIOD. UPPER-
LEVEL ENVIRONMENTAL CONDITIONS WILL CONTINUE TO DETERIORATE AS VWS 
INCREASES AND UPPER LEVEL DIVERGENCE DECREASES. THIS WEAKENING WILL 
BE ENHANCED DUE TO FRICTIONAL EFFECTS AS THE SYSTEM MAKES LANDFALL 
OVER CENTRAL LUZON NEAR TAU 60.
   C. IN THE EXTENDED TAUS, TY MAYSAK WILL RE-EMERGE OVER THE SOUTH 
CHINA SEA AND CONTINUE TRACKING WEST-NORTHWESTWARD WHILE WEAKENING 
DUE TO INCREASED VWS AND WEAK DIVERGENCE ALOFT. IN ADDITION, NEAR 
TAU 120, TY 04W WILL MOVE INTO SST BELOW 26 CELSIUS WHICH WILL 
FURTHER WEAKEN THE SYSTEM. OVERALL, DYNAMIC GUIDANCE HAS COME INTO 
BETTER AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC FORECAST 
TRACK.//
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