WTPS31 PGTW 221500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 20P (REUBEN) WARNING NR 003// RMKS/ 1. TROPICAL CYCLONE 20P (REUBEN) WARNING NR 003 02 ACTIVE TROPICAL CYCLONES IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 221200Z --- NEAR 26.0S 174.5W MOVEMENT PAST SIX HOURS - 165 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 065 NM NORTHEAST QUADRANT 075 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT REPEAT POSIT: 26.0S 174.5W --- FORECASTS: 12 HRS, VALID AT: 230000Z --- 26.9S 174.3W MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 185 DEG/ 04 KTS --- 24 HRS, VALID AT: 231200Z --- 27.6S 174.4W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER VECTOR TO 36 HR POSIT: 215 DEG/ 03 KTS --- 36 HRS, VALID AT: 240000Z --- 28.1S 174.8W MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 221500Z POSITION NEAR 26.2S 174.5W. TROPICAL CYCLONE 20P (REUBEN), LOCATED APPROXIMATELY 617 NM SOUTHEAST OF SUVA, FIJI, HAS TRACKED SOUTH-SOUTHEASTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM INTENSIFIED SLIGHTLY EVEN AS THE CONVECTION CONTINUES TO BE GREATLY SHEARED SOUTHEASTWARD AND PARTIALLY EXPOSING THE LOW LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS EXTRAPOLATED FROM A RAGGED LOW REFLECTIVITY CIRCULATION FEATURE IN THE 220935Z AMSU-B MICROWAVE IMAGE WITH LOW CONFIDENCE. UPPER LEVEL ANALYSIS INDICATES TC 20P HAS DRIFTED INTO AN AREA OF STRONG (30-50 KNOT) VERTICAL WIND SHEAR (VWS). HOWEVER, THE VWS IS PARTIALLY OFFSET BY EXCELLENT POLEWARD OUTFLOW, WHICH IS PROVIDING VENTILATION TO THE CONVECTION. THE CYCLONE IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF A MID-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. AFTER TAU 12, IT IS EXPECTED TO SLOW DOWN AS A MIGRATORY UPPER-LEVEL TROUGH PASSES TO THE SOUTH, WEAKENING THE STR AND CAUSING THE CYCLONE TO TRACK SOUTHWESTWARD. TC REUBEN HAS PEAKED AND INCREASING VWS AND COOLING SEA SURFACE TEMPERATURES WILL NOW BEGIN TO ERODE THE SYSTEM LEADING TO ITS DISSIPATION BY TAU 36 OR POSSIBLY SOONER. THERE IS NOW AN EVEN LARGER SPREAD AMONG THE AVAILABLE MODEL GUIDANCE, HENCE, THE JTWC TRACK FORECAST CONFIDENCE LEVEL REMAINS LOW. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 221200Z IS 16 FEET. NEXT WARNINGS AT 230300Z AND 231500Z. REFER TO TROPICAL CYCLONE 18P (NATHAN) WARNINGS (WTPS32 PGTW) FOR SIX-HOURLY UPDATES.//