WDPN32 PGTW 271500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W WARNING NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 271200Z AUG TO 011200Z SEP 2005.
   A. TROPICAL STORM (TS) 13W (TALIM), LOCATED APPROXIMATELY 280
NM NORTHWEST OF GUAM, HAS TRACKED NORTH-NORTHWESTWARD AT 11 KNOTS
OVER THE PAST SIX HOURS.
   B. TS 13W IS FORECAST TO TRACK NORTHWESTWARD OVER THE NEXT 12 TO
24 HOURS UNDER THE STEERING INFLUENCE OF A WEAK RIDGE TO THE EAST.
AS TS 13W TRACKS POLEWARD, IT WILL COME UNDER THE STEERING INFLUENCE
OF A LARGE ANTICYCLONE ANCHORED TO THE NORTH, AND BEGIN TO TRACK
WESTWARD ALONG THE SOUTHERN PERIPHERY OF THIS STRONGER STEERING RIDGE.
THE AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, NCEP GFS, COAMPS,
GFDN, AFWA MM5, UKMET EGRR, JGSM, JTYM, TCLAPS AND WBAR ARE IN FAIRLY
GOOD AGREEMENT WITH THIS SCENARIO. DIFFERENCES IN THE MODEL TRACKS
RESULT FROM VARIATIONS IN THE SIZE AND STRENGTH OF THE ANTICYCLONE
TO THE NORTH. THIS FORECAST IS BASED ON A CONSENSUS OF ALL AVAILABLE
DYNAMIC AIDS.
   C. ANIMATED WATER VAPOR IMAGERY INDICATES THAT OUTFLOW IS SUPP-
RESSED TO THE NORTHWEST DUE TO A WEAK UPPER LEVEL LOW NEAR 20N 130E.
UPPER LEVEL ANALYSIS REVEALS LOW TO MODERATE VERTICAL WIND SHEAR
WHICH IS FORECAST TO PERSIST FOR THE NEXT 72 HOURS. TS 13W WILL
INTENSIFY AT A LESS THAN CLIMATOLOGICAL RATE AS THE UPPER LEVEL LOW
TRACKS WESTWARD AHEAD OF THE CYCLONE, RESTRICTING OUTFLOW.
   D. CURRENT WIND RADII ARE BASED ON A 270911Z QUIKSCAT PASS. FORE-
CAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZED SYSTEM.
   E. IN THE EXTENDED FORECAST, TS 13W WILL TRACK WESTWARD ALONG THE
SOUTHERN PERIPHERY OF THE STEERING RIDGE ANCHORED TO THE NORTH. AFTER
TAU 96, TS 13W WILL BEGIN TO TRACK POLEWARD TOWARD A WEAKNESS IN THE
STEERING RIDGE CAUSED BY A MID-LATITUDE TROUGH EXITING ASIA. THOUGH
OUTFLOW IS FORECAST TO IMPROVE AS TS 13W APPROACHES THE AXIS OF THE
STEERING RIDGE LATE IN THE FORECAST PERIOD, INTENSIFICATION WILL BE
SLOWED AS A RESULT OF DISRUPTION OF INFLOW DUE TO INTERACTION WITH
LAND, AND INTRUSION OF DRY, CONTINENTAL AIR.
3. FORECAST TEAM: BRAVO//