Tropical Storm MAYSAK Advisory Cu, 03.04.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (MAYSAK) WARNING NR 28//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 04W (MAYSAK), LOCATED APPROXIMATELY 636 NM EAST OF
MANILA, PHILIPPINES HAS TRACKED NORTHWESTWARD AT 08 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
DEPICTS A WEAKENING CONVECTIVE CORE STRUCTURE THAT IS SHEARING
NORTHEASTWARD DUE TO ENCOUNTERING HIGH (30 KNOT) SOUTHWESTERLY
VERTICAL WIND SHEAR (VWS) ASSOCIATED WITH A MID-LATITUDE TROUGH TO
THE WEST. A 021808Z SSMI 89GHZ MICROWAVE IMAGE CONTINUES TO SHOW A
MICROWAVE EYE FEATURE, HOWEVER, ALL OF THE CONVECTION IS DISPLACED
TO THE NORTHEAST WITH DRY AIR WRAPPING AROUND THE SOUTHERN PERIPHERY
FROM THE WEST. UPPER LEVEL ANALYSIS INDICATES SIGNIFICANT DRY AIR
BEING ADVECTED INTO THE PHILIPPINE SEA BY THE AFOREMENTIONED TROUGH.
THESE FACTORS ARE OFFSETTING THE VIGOROUS POLEWARD OUTFLOW EVIDENT
ON THE WATER VAPOR LOOP. THE INITIAL POSITION IS BASED ON THE
MICROWAVE EYE FEATURE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS
HEDGED SLIGHTLY LOWER THAN DVORAK CURRENT INTENSITY ESTIMATES OF
T5.5 (105 KNOTS) TO REFLECT THE SYSTEM'S WEAKENING STRUCTURE. TY
MAYSAK IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP
LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 04W WILL CONTINUE TRACKING NORTHWESTWARD THROUGH TAU 24
UNDER THE INFLUENCE OF THE STEERING STR. BETWEEN TAU 24 AND 36, TY
MAYSAK WILL TURN SLIGHTLY WESTWARD AS THE SHORTWAVE TROUGH
PROPAGATES EAST AND AN EXTENSION OF THE STEERING STR BUILDS IN NORTH
OF THE SYSTEM. BEYOND TAU 36, THE SYSTEM WILL TRACK NORTHWESTWARD
AGAIN AS THE STR REORIENTS TO ITS ORIGINAL POSITION TO THE
NORTHEAST. UPPER LEVEL ENVIRONMENTAL CONDITIONS WILL CONTINUE TO
DETERIORATE AS VWS INCREASES THROUGH TAU 36 AND UPPER LEVEL
DIVERGENCE DECREASES. AS THE UPPER LEVEL TROUGH MOVES OUT OF THE
REGION VWS WILL DROP BACK TO MARGINAL LEVELS, CAUSING A SLOWER
WEAKENING JUST PRIOR TO LANDFALL. BEYOND TAU 48, THE WEAKENING WILL
BE ENHANCED DUE TO FRICTIONAL EFFECTS AS THE SYSTEM MAKES LANDFALL
OVER CENTRAL LUZON. AS TY 04W RE-EMERGES BACK OVER WATER IN THE
SOUTH CHINA SEA, IT WILL CONTINUE WEAKENING DUE TO HIGH VWS AND WEAK
DIVERGENCE ALOFT.
   C. IN THE EXTENDED TAUS, TY MAYSAK WILL FURTHER WEAKEN DUE TO THE
POOR ENVIRONMENTAL CONDITIONS. NEAR TAU 120, A STRONG NORTHEASTERLY
SURGE THROUGH THE TAIWAN STRAIT WILL FORCE THE WEAKENED SYSTEM TO
BEND WESTWARD. IN ADDITION TO A POOR UPPER LEVEL ENVIRONMENT, TY 04W
WILL ALSO ENCOUNTER SST BELOW 26 CELSIUS. OVERALL, DYNAMIC GUIDANCE
REMAINS IN GOOD AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC
FORECAST TRACK.//
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