UNCLAS//N03144//
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 31W (PONGSONA) WARNING 
NR 16//
RMKS/
WDPN31 PGTW 061500
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 061200Z9 TO 091200Z2 DEC 02.
   A. TYPHOON (TY) 31W (PONGSONA), LOCATED APPROXIMATELY 130 NM
NORTH-NORTHWEST OF CHUUK, HAS TRACKED WESTWARD AT 10 KNOTS OVER 
THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 061130Z1 
ENHANCED INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED 
ON SATELLITE CURRENT INTENSITY ESTIMATES OF 90 KNOTS. A 060953Z3 
SPECIAL SENSOR MICROWAVE IMAGER (SSM/I) PASS REVEALS THAT THE 
BANDING EYE FEATURE REMAINS. THE 060747Z4 QUIKSCAT PASS AND SYNOPTIC 
DATA REVEAL EXPANDED WIND RADII AT THE SURFACE FOR THIS SYSTEM. 
   B.  THE DEVELOPING BAROCLINIC SYSTEM EAST OF JAPAN IS BEGINNING 
TO CAUSE WEAKENING IN THE RIDGE NORTH OF THE SYSTEM AND IS FORECAST 
TO EFFECT A MORE POLEWARD TRACK IN THE EARLY PERIOD. AFTERWARD, TY 
31W WILL MAINTAIN A POLEWARD TRACK INTO THE WEAKNESS UNTIL THE LATE 
PERIOD, AT WHICH TIME THE SYSTEM IS FORECAST TO BEGIN TO TAKE A MORE 
NORTH-NORTHEASTWARD TRACK AS IT BEGINS INTERACTING WITH THE MID-
LATITUDE FLOW. THE AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, 
GFDN, NCEP AVIATION (AVN), JAPAN GLOBAL (JGSM) AND TYPHOON (JTYM), 
AND UKMET (EGRR) ARE IN GOOD AGREEMENT WITH THIS SCENARIO, WITH GFDN 
TRACKING TO THE LEFT OF THE CONSENSUS SLIGHTLY. COAMPS AND AFWA MM5 
REMAIN THE OUTLIERS WITH COAMPS MAINTAINING AN EQUATORWARD BIAS AND 
MM5 HOLDING WITH A POLEWARD BIAS. OUR FORECAST IS BASED ON A 
CONSENSUS OF THE AVAILABLE DYNAMIC AIDS WITH LESS EMPHASIS ON COAMPS 
AND MM5.
   C. A CLIMATOLOGICAL INTENSIFICATION RATE IS FORECAST AS THE 
SYSTEM TRACKS TOWARD THE SUBTROPICAL RIDGE AXIS. BY THE END OF THE 
PERIOD, THE SYSTEM WILL HAVE REACHED PEAK INTENSITY AND BEGUN TO 
SLOWLY DECREASE IN THE FINAL HOURS OF THIS FORECAST PERIOD AS IT 
BEGINS INTERACTING WITH THE MID-LATITUDE FLOW NORTH OF THE RIDGE.  
   D. INITIAL WIND RADII ARE BASED ON A RECENT QUIKSCAT PASS. 
FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE-SIZED 
SYSTEM.
FORECAST TEAM: BRYANT/INGRAM/JACOBS/JUAREZ/KUMAGA//

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