WDPN31 PGTW 021500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE)
WARNING NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 01W (ONE) HAS FORMED WITHIN THE REVERSE-
ORIENTED MONSOON TROUGH, SLOWLY DEEPENED AND REMAINED QUASI-
STATIONARY OVER THE PAST 12 HOURS. A 021003Z SSMI IMAGE SHOWS DEEP
CONVECTION OVER A WELL FORMED LOW LEVEL CIRCULATION CENTER (LLCC)
WITH DEEP CONVECTIVE BANDING WRAPPING AROUND THE NORTHERN FLANK OF 
THE LLCC AND INTO THE CENTER. A 020944Z QUIKSCAT PASS DEPICTS A WELL 
FORMED CIRCULATION CENTER DESPITE THE PROXIMITY TO LAND WITH 35 KT 
RAIN-FLAGGED WINDS. THE SYSTEM IS LOCATED UNDER THE UPPER-LEVEL 
RIDGE AXIS WHICH HAS PROVIDED GOOD RADIAL OUTFLOW, AS EVIDENT IN 
ANIMATED WATER VAPOR IMAGERY. THIS, ALONG WITH FAVORABLE SEA 
SURFACE TEMPERATURES HAS HELPED THE SYSTEM DEVELOP DESPITE ITS
PROXIMITY TO LAND. COMPETING STEERING INFLUENCES BY NORTHEASTERLY 
MONSOONAL FLOW AND SOUTHWEST FLOW FROM THE NORTHWEST QUADRANT OF THE 
SURFACE RIDGE TO THE SOUTH HAS LED TO A SLOW TRACK SPEED FOR THE 
SYSTEM. THE CURRENT POSITION AND INTENSITY IS BASED ON RECENT 
SATELLITE INTENSITY FIXES FROM KNES AND PGTW THAT RANGED FROM 30 TO 
35 KNOTS ALONG WITH SHORE BASED OBSERVATIONS AND LOCAL SHIP 
OBSERVATIONS. 
3. FORECAST REASONING
   A. THE FORECAST PHILOSOPHY HAS CHANGED SLIGHTLY SINCE THE 06Z
FORECAST.  THE SYSTEM IS NOW EXPECTED TO DRIFT MORE TOWARDS THE
EAST DURING THE NEXT 36 HOURS THAN PREVIOUSLY FORECASTED.
   B. TS 01W WILL REMAIN QUASI-STATIONARY THROUGH TAU 24 TO 36. AN
APPROACHING MID-LATITUDE TROUGH WILL INTERRUPT THE NORTHEASTERLY
MONSOONAL FLOW THROUGH THE LUZON STRAIT AFTER TAU 36. AFTER THIS
TIME THE SURFACE RIDGE TO THE SOUTH WILL BECOME THE DOMINATE STEERING
INFLUENCE AND THE SYSTEM WILL ACCELERATE. AS THE SYSTEM MOVES AWAY
FROM THE EFFECTS OF LAND IT IS EXPECTED TO INTENSIFY. HIGH VERTICAL 
WINDSHEAR WILL START TO EFFECT THE SYSTEM THE FURTHER NORTH
IT TRAVELS AND THIS IS EXPECTED TO SUPPRESS EXTENSIVE DEVELOPMENT.
   C. AFTER TAU 72 THE SYSTEM WILL CONTINUE TO TRACK TOWARDS THE
EAST-NORTHEAST ALONG THE EDGE OF THE BAROCLINIC ZONE WHERE 
INCREASING LEVELS OF VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT
WILL START TO WEAKEN THE SYSTEM.
FORECAST TEAM: CHARLIE//
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