WDPN31 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (MAYSAK) WARNING NR 13//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 04W (MAYSAK), LOCATED APPROXIMATELY 526 NM EAST OF 
YAP, HAS TRACKED WESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. 
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP 
CONVECTIVE SPIRAL BANDING WRAPPING INTO A CENTRAL CORE THAT REMAINS 
SLIGHTLY ELONGATED. A 292320Z MHS 89GHZ MICROWAVE IMAGE SHOWS THE 
MOST INTENSE BANDING TO THE NORTH AND WRAPPING INTO THE LOW LEVEL 
CIRCULATION CENTER. UPPER LEVEL ANALYSIS INDICATES RADIAL OUTFLOW, 
WHICH CAN BE SEEN ON WATER VAPOR IMAGERY, WITH 10 TO 20 KNOT 
SOUTHEASTERLY VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS 
BASED ON THE AFOREMENTIONED MICROWAVE IMAGE AND THE MSI LOOP WITH 
GOOD CONFIDENCE. THE INITIAL INTENSITY IS BASED ON AN ASSESSMENT OF 
MULTI-AGENCY CURRENT INTENSITY ESTIMATES RANGING FROM 77 TO 90 KNOTS 
AND SUPPORTED BY A SATCON INTENSITY ESTIMATE OF 83 KNOTS. TY MAYSAK 
IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE DEEP LAYERED 
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TY 04W WILL CONTINUE TRACKING WESTWARD UNDER THE INFLUENCE OF 
THE DOMINANT STEERING STR THROUGH TAU 48. TY MAYSAK IS FORECAST TO 
CONTINUE INTENSIFYING OVER THE NEXT 48 HOURS DUE TO FAVORABLE UPPER 
LEVEL CONDITIONS AND WARM SEA SURFACE TEMPERATURES (29 CELSIUS). 
BEYOND TAU 48, TY 04W WILL TURN NORTHWESTWARD AS THE STEERING STR 
WEAKENS AND REORIENTS DUE TO A PASSING SHORTWAVE TROUGH TO THE 
NORTH. DURING THIS TIME, THE TYPHOON WILL ENCOUNTER INCREASED VWS AS 
IT GAINS LATITUDE AND BEGIN ITS WEAKENING TREND.
   C. NEAR TAU 96, THE SHORTWAVE TROUGH WILL MOVE DOWNSTREAM FROM 
THE STEERING STR CAUSING THE STR TO BUILD BACK IN NORTH OF THE 
SYSTEM, CREATING A WEST-NORTHWESTWARD TRACK. AS TY 04W CONTINUES TO 
GAIN LATITUDE IT WILL WEAKEN IN RESPONSE TO INCREASED VWS (20-25 
KNOT). THERE IS NOW A SLIGHT BIFURCATION IN DYNAMIC MODEL GUIDANCE 
NEAR TAU 72. COAMPS-TC AND GFDN TRACK A WEAKER SYSTEM MUCH FASTER 
AND ON A WESTWARD TRACK INTO THE CENTRAL PHILIPPINES. THE REMAINING 
GUIDANCE IS STILL IN TIGHT AGREEMENT ON A NORTHWESTWARD TRACK 
TOWARDS LUZON. BASED ON THE CURRENT INTENSITY FORECAST, THE NORTHERN 
TRACK IS MORE FEASIBLE AND, AS SUCH, THERE IS STILL HIGH CONFIDENCE 
IN THE JTWC TRACK FORECAST.//
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