WDPN31 PGTW 251500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION (TD) 17W/
WARNING NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 251200Z0 TO 281200Z3 SEP 2003.
   A. TROPICAL DEPRESSION (TD) 17W, LOCATED APPROXIMATELY 
740 NM SOUTHEAST OF OKINAWA, HAS REMAINED QUASISTATIONARY
OVER THE PAST 06 HOURS. THE WARNING POSITION 
IS BASED ON 251130Z2 INFRARED SATELLITE IMAGERY. THE 
WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY 
ESTIMATES OF 25 AND 30 KNOTS. ANIMATED SATELLITE IMAGERY AND A 
250914Z1 SPECIAL SENSOR MICROWAVE IMAGERY (SSMI) CONTINUE TO 
DEPICT A BROAD CIRCULATION WITHIN A MONSOON TROUGH. A TUTT 
CELL TO THE NORTH-NORTHEAST CONTINUES TO SUPRESS DEVELOPMENT
AND CURB DEEP CONVECTIVE ACTIVITY ON THE POLEWARD SIDE.
ADDITIONALLY, A RECENT TROPICAL RAINFALL MEASURING MISSION
SUGGESTED A SECOND CIRCULATION TO THE NORTHEAST OF THE CURRENT
BEST TRACK POSITION. 
   B. TD 17W IS EXPECTED MOVE SLOWLY FOR THE NEXT 12 TO 24
HRS AS IT CONSOLIDATES AND INTENSIFIES. AFTERWARDS, TD 17W IS
FORECAST TO TURN NORTHEAST WITH THE DEVELOPMENT NEAR EQUATORIAL
RIDGE AND A SHIFT IN THE MID-LEVEL SUBTROPICAL RIDGE. THIS 
TRANSITION WILL BE AIDED BY THE PASSAGE OF A SHORTWAVE TROUGH
DURING THE NEXT 24 HOURS. TD 17W IS EXPECTED TO TRACK NORTH-
NORTHEAST THROUGH THE REMAINDER OF THE FORECAST PERIOD ALONG
THE WESTERN EXTENT OF THE RE-ORIENTED SUBTROPICAL RIDGE. 
THE AVAILABLE DYNAMIC AIDS, NOGAPS, COAMPS, UKMET EGRR, GFS,
GFDN, AND JAPAN GLOBAL (JGSM) AND TYPHOON (JTYM) ARE IN FAIR
AGREEMENT WITH THIS FORECAST SCENARIO. HOWEVER, THIS
SCENARIO CAN BE OVER-FORECASTED IN DYNAMIC MODELS WHICH 
WOULD RESULT IN A SLOWER TRANSITION AND PROPAGATION FURTHER WEST
THAN FORECASTED. THIS FORECAST IS BASED ON A CONSENSUS OF THE
AVAILABLE DYNAMIC AIDS WITH CONSIDERATION FOR PERSISTENCE. 
   C. TD 17W HAS BEEN SLOW TO DEVELOP WITH OUTFLOW
INHIBITED BY A TUTT CELL SITUATED CLOSE BY TO THE NORTHEAST.
WITHIN 24 HOURS, THIS TUTT CELL IS EXPECTED TO WEAKEN, IMPROVING
OUTFLOW CONDITIONS. TD 17W IS EXPECTED TO INTENSIFY SLOWLY
INITIALLY BEFORE MORE FAVORABLE OUTFLOW RESULTS IN IMPROVED DEVELOPMENT
POTENTIAL.  
   D. FORECAST WIND RADII ARE BASED ON THE HUNTLEY MODEL AND REVIEW OF 
THE DYNAMIC MODEL WIND FIELDS.
3. FORECAST TEAM: SMITH/NOREN/WINDES/PHILIPS/BIRD//

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