WDPN31 PGTW 170300 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (DIANMU)
/WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 170000Z8 TO 220000Z4 JUN 2004.
   A. SUPER TYPHOON (STY) 09W (DIANMU) LOCATED APPROXIMATELY 
675 NM SOUTHEAST OF THE ISLAND OF OKINAWA, HAS TRACKED NORTH-
WESTWARD AT 07 KNOTS OVER THE PAST 06 HOURS. THE WARNING 
POSITION IS BASED ON 162330Z5 MULTISPECTRAL SATELLITE 
IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT 
INTENSITY ESTIMATES OF 140 AND 155 KNOTS. MULTISPECTRAL 
SATELLITE IMAGERY REVEALS A 10 NM SYMMETRICAL EYE. 
   B. STY 09W IS FORECAST TO CONTINUE TRACKING POLEWARD 
THROUGHOUT THE FORECAST PERIOD ALONG THE WESTERN PERIPHERY OF 
THE STEERING RIDGE TO THE NORTHEAST. MODEL ANALYSIS DEPICTS A 
WEAK APPROACHING TROUGH THAT WILL HAVE LIMITED EFFECT ON THE 
STEERING RIDGE, MAINTAINING A STEERING ENVIRONMENT TOWARD THE 
NORTHWEST IN THE VICINITY OF OKINAWA. AT TAU 72, SLIGHT 
WEAKENING OF THE STEERING RIDGE WILL OCCUR FROM A SECOND TROUGH 
WHEN THE SYSTEM IS LOCATED POLEWARD OF RIDGE AXIS, AND THE 
RESULTANT CHANGE WILL INFLUENCE THE TRACK MORE TOWARD THE NORTH-
NORTHEAST. THE AVAILABLE DYNAMIC AIDS, CONSISTING OF NOGAPS, 
GFDN, UKMET, TCLAPS, COAMPS, AFWA MM5 AND NCEP GFS, ARE IN FAIR 
AGREEMENT WITH THIS SCENARIO. THIS FORECAST IS BASED ON 
PERSISTENCE AND A CONSENSUS OF ALL AVAILABLE DYNAMIC AIDS.
   C. THE TUTT CELL RESPONSIBLE FOR STY 09W EXPLOSIVE DEEPENING 
HAS FILLED, BUT EXCELLENT RADIAL OUTFLOW IS MAINTAINING SYSTEM
STRENGTH. STIPS/ICON INTENSITY GUIDANCE ARE BRINGING DOWN THE 
INTENSITY GRADUALLY AS STY 09W MOVES POLEWARD. UPPER LEVEL 
RIDGING, INCREASED VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT 
ARE THE LIKELY CAUSE. SLIGHT INCREASE IN INTENSITY IS FORECAST 
AS SYSTEM PASSES THE RIDGE AXIS AND POLEWARD OUTFLOW INCREASES
AROUND TAU 72.
   D. CURRENT WIND RADII ARE BASED ON A RECENT QUIKSCAT PASS.
FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZED
SYSTEM. 
   E. THE EXTENDED FORECAST TRACKS STY 09W POLEWARD WITH A MORE
NORTH-NORTHEASTERLY COMPONENT TO THE TRACK, AS THE SECOND TROUGH 
PASSES EASTWARD. THE SYSTEM IS FORECAST TO WEAKEN AFTER 72 HOURS 
IN A LESS FAVORABLE UPPER LEVEL ENVIRONMENT WITH DECREASING 
OUTFLOW ALOFT.
3. FORECAST TEAM: ARENDS/KLINZMANN/HEILER//

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