Tropical Storm MAYSAK Advisory 02.04.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (MAYSAK) WARNING NR 25//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 04W (MAYSAK), LOCATED APPROXIMATELY 764 NM EAST OF
MANILA, PHILIPPINES HAS TRACKED WEST-NORTHWESTWARD AT 08 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A DEEP CONVECTIVE CENTRAL CORE WITH A BROADENING 27-NM EYE
THAT SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. THE WATER
VAPOR LOOP SHOWS THAT THE TYPHOON IS STRUGGLING TO MAINTAIN ITS
CONVECTIVE CORE DUE TO DRY AIR WRAPPING INTO THE CIRCULATION. UPPER
LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH 10 TO 20 KNOT
VERTICAL WIND SHEAR (VWS) WITH GOOD POLEWARD OUTFLOW, HOWEVER,
SIGNIFICANT DRY AIR THROUGH THE MID AND UPPER LEVELS IS IMPEDING
FURTHER DEVELOPMENT. THE INITIAL INTENSITY OF 115 KNOTS IS BASED ON
CONSENSUS AGENCY CURRENT INTENSITY ESTIMATES OF T6.0 (115 KNOTS). 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 (25-30 KNOTS) AND UPPER LEVEL DIVERGENCE DECREASES. THIS
WEAKENING WILL BE ENHANCED DUE TO FRICTIONAL EFFECTS AS THE SYSTEM
MAKES LANDFALL OVER CENTRAL LUZON JUST BEFORE TAU 72.
   C. BEYOND TAU 72, TY MAYSAK WILL TRACK THROUGH CENTRAL LUZON
UNDER THE INFLUENCE OF THE STEERING STR. THE SYSTEM WILL CONTINUE TO
WEAKEN WHEN IT EMERGES IN THE SOUTH CHINA SEA DUE TO INCREASED VWS
(15-20 KNOT) AND WEAK DIVERGENCE ALOFT. IN ADDITION, NEAR TAU 120,
TY 04W WILL MOVE INTO SEA SURFACE TEMPERATURES BELOW 26 CELSIUS
WHICH WILL FURTHER WEAKEN THE SYSTEM. DYNAMIC MODEL GUIDANCE IS IN
TIGHT AGREEMENT THROUGH TAU 72, HOWEVER, THERE REMAINS A SLIGHT
SPREAD (150 NM) AS IT TRACKS THROUGH LUZON AND ENTERS THE SOUTH
CHINA SEA. BASED ON THE FORECASTED INTENSITY, THE CURRENT WEST-
NORTHWESTWARD TO NORTHWESTWARD TRACK THROUGHOUT THE FORECAST PERIOD
IS THE MOST PLAUSIBLE. THEREFORE, THERE IS HIGH CONFIDENCE IN THE
JTWC FORECAST.//
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