WDPN32 PGTW 221500 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON (TY) 04W WARNING 
NR 12//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 221200Z6 TO 251200Z0 JUN 01.
   A. TYPHOON 04W (CHEBI), LOCATED APPROXIMATELY 125 NM NORTH-
NORTHWEST OF PORT SAN VICENTE, HAS TRACKED NORTHWESTWARD AT 16 KNOTS 
DURING THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 221130Z9 
INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON 
CURRENT INTENSITY ESTIMATES OF 65 AND 77 KNOTS. ANIMATED SATELLITE 
IMAGERY DEPICTS SLOWLY DEEPENING CONVECTION OVER A LOW-LEVEL 
CIRCULATION CENTER. WATER VAPOR IMAGERY INDICATES A MID TO UPPER 
LEVEL RIDGE POSITIONED NORTHEAST OF THE SYSTEM.
   B. THE MID-LEVEL SUBTROPICAL RIDGE EXTENDING WESTWARD FROM A HIGH 
NORTH OF THE MARIANA ISLANDS SHOULD MAINTAIN STRENGTH THROUGH THE 
FORECAST PERIOD. THEREFORE, TY 04W IS FORECAST TO TRACK 
NORTHWESTWARD THROUGH THE 24 HOUR FORECAST PERIOD AND THEN 
INCREASINGLY NORTHWARD INTO CHINA. THE NOGAPS MODEL AND THE 
NAVY GEOPHYSICAL FLUID DYNAMICS (GFDN) MODEL ARE IN FAIR AGREEMENT 
TRACKING THE SYSTEM NORTHWESTWARD THROUGH THE FORECAST PERIOD. 
THE JMA GLOBAL SPECTRAL AND THE JMA TYPHOON MODELS TRACK THE SYSTEM 
MORE NORTHWARD. THE UKMET OFFICE MODEL (EGRR) LOSES THE SYSTEM AFTER
24 HOURS. THE NUMERICAL CONSENSUS CONSISTS OF 4 MODELS. THE OFFICIAL 
FORECAST IS BASED ON A BLEND OF PERSISTENCE WITH THE NUMERICAL 
CONSENSUS.
   C. THE SYSTEM SHOULD INTENSIFY AS IT TRACKS NORTHWESTWARD INTO A 
MORE FAVORABLE UPPER LEVEL ENVIRONMENT BEFORE MAKING LANDFALL OVER 
CHINA.  
   D. THE WIND RADII ARE BASED ON CLIMATOLOGY. WIND RADII FOR THE 
36, 48, AND 72 HOUR FORECAST ARE OMITTED OVER LAND.
FORECAST TEAM: MAZANY/PARKER/EDBERG//

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