WDPN32 PGTW 031500
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 031200Z6 TO 061200Z9 SEP 02.
   A. TYPHOON (TY) 22W, LOCATED APPROXIMATELY 330 NM EAST OF KADENA,
HAS TRACKED WESTWARD AT 10 KNOTS DURING THE PAST 6 HOURS. THE
WARNING POSITION IS BASED ON 031130Z8 ENHANCED INFRARED SATELLITE
IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT
INTENSITY ESTIMATES OF 90 KNOTS. A RECENT SSM/I PASS REVEALS TY 22W 
MAINTAINS A LARGE EYE OF APPROXIMATELY 60 NM AND DEEP CONVECTION 
SYMMETRIC ABOUT THE LOW LEVEL CIRCULATION CENTER (LLCC). ANIMATED
WATER VAPOR IMAGERY AND RECENT MICROWAVE IMAGERY ALSO DEPICT SOME
DRY AIR ENTRAINMENT FROM THE WEST OF THE SYSTEM.
   B. TY 22W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE
MID-LEVEL SUBTROPICAL RIDGE CENTERED NORTHEAST OF THE SYSTEM. AS TY
22W TRACKS WESTWARD THIS RIDGE IS EXPECTED TO SHIFT EAST, WHILE A
MID-LEVEL HIGH HEIGHT CENTER BUILDS OVER EASTERN CHINA. DURING THE
MID PERIOD, A WEAKNESS BETWEEN THE RIDGE TO THE NORTHEAST AND THE
HIGH HEIGHT CENTER OVER EASTERN CHINA WILL RESULT IN A SLIGHTLY MORE
NORTHWESTERN INFLUENCE IN THE OVERALL WESTERN TRACK. AFTER THE MID
PERIOD, THE CENTER TO THE WEST OF THE SYSTEM WILL BECOME THE
DOMINANT STEERING MECHANISM, RESULTING IN A SUBTLE TURN TOWARDS THE
SOUTHWEST. THE AVAILABLE DYNAMICAL MODELS INCLUDING NCEP AVIATION
(AVN), NOGAPS, UKMET GLOBAL (EGRR), AND THE JMA GLOBAL (JGSM) AND
TYPHOON (JTYM) MODELS ARE IN GOOD AGREEMENT WITH THIS SCENARIO. GFDN
IS IN GOOD AGREEMENT UNTIL THE LATE PERIOD, WHEN THE MODEL SHOWS
ERRONEOUS INTERACTIONS WITH OTHER CIRCULATIONS, CREATING A SLIGHTLY
MORE POLEWARD TRACK. OUR FORECAST IS BASED ON A BLEND OF ALL THE
AVAILABLE DYNAMIC AIDS.
   C. THOUGH THERE HAS BEEN SLIGHT RE-INTENSIFICATION OVER THE PAST
12 HOURS DUE TO THE SYSTEM TRACKING OVER WARMER SEA SURFACE
TEMPERATURES, MILD TO MODERATE DRY AIR ENTRAINMENT WILL ACT AS A
COUNTERING INFLUENCE, CREATING A MARGINAL ENVIRONMENT. FOR THE
REMAINDER OF THE PERIOD TY 22W IS NOT FORECAST TO INTENSIFY
SIGNIFICANTLY, THOUGH IT WILL MAINTAIN AN INTENSITY CLOSE TO THE
CURRENT INTENSITY.
   D. INITIAL WIND RADII ARE BASED ON A RECENT QUIKSCAT PASS AND
SATELLITE ANALYSIS. WIND FORECAST RADII ARE BASED ON CLIMATOLOGY FOR
AN AVERAGE-SIZED SYSTEM.
FORECAST TEAM: BRYANT/JACOBS/SHERRY/NUTONGLA/JUAREZ//

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