WDPN32 PGTW 230300
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 230000Z5 TO 260000Z8 MAY 03.
   A. TYPHOON (TY) 04W (CHAN-HOM), LOCATED APPROXIMATELY 390 NM 
EAST-NORTHEAST OF GUAM, HAS TRACKED NORTH-NORTHWESTWARD AT 07 KNOTS 
OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED ON 222300Z9 
ENHANCED INFRARED AND VISIBLE SATELLITE IMAGERY. THE WARNING 
INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 65 TO 
102 KNOTS. SATELLITE IMAGERY DEPICTS A 20NM DIAMETER EYE.
   B. TY 04W IS FORECAST TO CONTINUE TRACKING POLEWARD ALONG THE  
WESTERN PERIPHERY OF THE MID-LEVEL SUBTROPICAL RIDGE TO THE 
NORTHEAST TOWARDS A WEAKNESS IN THE RIDGE. THIS WEAKNESS IS BEING 
ENHANCED BY A SHORTWAVE TROUGH TRACKING EASTWARD AND WELL NORTH OF 
THE SYSTEM. A SECOND SHORTWAVE TROUGH WILL FURTHER ERODE THE RIDGE 
LATER IN THE PERIOD, EFFECTING A MORE NORTH-NORTHEASTWARD TRACK. THE 
AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, NCEP (GFS), JGSM, JTYM, 
GFDN, AND UKMET GLOBAL (EGRR) REMAIN IN GOOD AGREEMENT THROUGH THE 
MID-PERIOD FOR TRACK DIRECTION. AFTERWARDS, THE MODELS VARY AS TO 
THE SPEED OF ADVANCE FOR THE SYSTEM. JTYM INTERACTS THE SYSTEM 
RATHER QUICKLY WHILE BEING COMPENSATED BY EGRR, THE SLOWEST OF THE 
MODELS. THIS FORECAST IS BASED ON PERSISTENCE AND A CONSENSUS OF THE 
DYNAMIC AIDS. 
   C. THE SYSTEM IS EXPECTED TO INTENSIFY STEADILY THROUGH 48 HOURS 
IN A FAVORABLE UPPER LEVEL ENVIRONMENT WITH POLEWARD OUTFLOW 
POTENTIAL PROVIDED BY A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) 
EAST OF THE SYSTEM. AFTER 48 HOURS, TY 04W IS EXPECTED TO BEGIN 
WEAKENING UNDER INCREASING VERTICAL WIND SHEAR AND COOLER SEA 
SURFACE TEMPERATURES. 
   D. CURRENT WIND RADII BASED ON A RECENT QUIKSCAT PASS. FORECAST 
WIND RADII ARE BASED ON CLIMATOLOGY FOR AN INTENSIFYING AVERAGE-
SIZED SYSTEM.
FORECAST TEAM: MAZANY/KLINZMANN/MENEBROKER/BIRD//

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