WDPN32 PGTW 261500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W WARNING NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM 15W (TALAS), LOCATED APPROXIMATELY 185 NM
SOUTH-SOUTHWEST OF IWO TO, JAPAN, HAS TRACKED NORTH-NORTHEASTWARD
AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE 
IMAGERY SHOWS DEEP CONVECTIVE BANDING HAS FURTHER CONSOLIDATED AND
EXPANDED INTO THE NORTHERN QUADRANT OF THE STORM. A 261200Z ASCAT
PASS DEPICTS WIDE SWATHS OF 35- TO 40-KNOT UNFLAGGED WIND BARBS
ALONG THE NORTHERN TO EASTERN AND ALONG THE SOUTHERN PERIPHERIES,
WITH WEAKER WINDS TOWARDS THE CENTER, CHARACTERISTIC OF A MONSOON
DEPRESSION. THE INITIAL POSITION WAS BASED ON THE ABOVE ANIMATION
AND ENCLOSED IN A NOTCH FEATURE ON A 261023Z 37HZ SSMIS MICROWAVE
IMAGE. THE INITIAL INTENSITY WAS BASED ON PGTW, KNES, AND RJTD
DVORAK ESTIMATES. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS UNDER
A RIDGE AXIS IN AN AREA OF LOW (05-10 KT) VERTICAL WIND SHEAR (VWS).
A WATER VAPOR SATELLITE LOOP SHOWS A TROPICAL UPPER TROPOSPHERIC
TROUGH (TUTT) IS CAUSING SUBSIDENCE ALONG THE NORTHWESTERN
PERIPHERY, HOWEVER, A TUTT CELL TO THE NORTHEAST IS ENHANCING
POLEWARD OUTFLOW. ADDITIONALLY, THE SYSTEM MAINTAINS AN EXCELLENT
EQUATORWARD OUTFLOW CHANNEL, GENERATED BY THE RIDGE AXIS OVERHEAD.
TS 15W IS CURRENTLY TRACKING ALONG THE NORTHEASTERN EXTENSION OF A
NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY.
   B. TS 15W IS EXPECTED TO CONTINUE TRACKING NORTHEASTWARD UNDER
THE STEERING INFLUENCE OF THE NER UP TO TAU 36, AFTERWHICH, A
BUILDING SUBTROPICAL RIDGE TO THE NORTHEAST WILL STEER THE SYSTEM
ON A NORTHWEST PROGRESSION. ENVIRONMENTAL CONDITIONS WILL REMAIN
FAVORABLE FOR GRADUAL INTENSIFICATION. 
   C. AFTER TAU 72, TS TALAS WILL ROUND THE STR AND BEGIN TO RECURVE
NORTHEASTWARD. THE INITIAL EXPOSURE TO THE STRONG WESTERLIES WILL
ENHANCE POLEWARD OUTFLOW AND OFFSET INCREASING VWS, PROMOTING
MINIMAL INTENSIFICATION THROUGH THE REMAINDER OF THE FORECAST. THE
AVAILABLE NUMERICAL GUIDANCE REFLECTS THE TWO STEERING FORCES BUT
SPREADS OUT TO ABOUT 30 DEGREES WITH NOGAPS AS THE LEFTMOST AND GFS
THE RIGHTMOST OUTLIER. THIS TRACK FORECAST IS OVER BUT FASTER THAN
CONSENSUS DURING THE FIRST HALF OF THE FORECAST TO OFFSET WBAR'S
ERRONEOUSLY SLOW STORM MOTION, THEN SLIGHTLY TO THE LEFT TO ADJUST
FOR NOGAPS' EXCESSIVE PULL TO THE LEFT.//
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