WTPS32 PGTW 042100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE WARNING// RMKS/ 1. TROPICAL CYCLONE 17P (IRIS) WARNING NR 023 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 041800Z --- NEAR 19.7S 151.7E MOVEMENT PAST SIX HOURS - 125 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 045 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 - 090 NM NORTHEAST QUADRANT 125 NM SOUTHEAST QUADRANT 105 NM SOUTHWEST QUADRANT 085 NM NORTHWEST QUADRANT REPEAT POSIT: 19.7S 151.7E --- FORECASTS: 12 HRS, VALID AT: 050600Z --- 19.8S 152.0E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT 115 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 045 DEG/ 01 KTS --- 24 HRS, VALID AT: 051800Z --- 19.7S 152.1E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 025 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 310 DEG/ 02 KTS --- 36 HRS, VALID AT: 060600Z --- 19.4S 151.7E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 145 NM SOUTHEAST QUADRANT 125 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 315 DEG/ 03 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 061800Z --- 18.9S 151.2E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER RADIUS OF 034 KT WINDS - 015 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 005 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 335 DEG/ 03 KTS --- 72 HRS, VALID AT: 071800Z --- 17.8S 150.6E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 042100Z POSITION NEAR 19.7S 151.8E. TROPICAL CYCLONE 17P (IRIS), LOCATED APPROXIMATELY 376 NM EAST- SOUTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED SOUTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED EIR SATELLITE IMAGERY SHOWS A PARTLY-EXPOSED LLCC PEEKING OUT OF THE CONVECTIVE DENSE OVERCAST REGION THAT HAS REFORMED OVER 17P IN THE PAST 6 HOURS. THE INITIAL POSITION IS BASED ON EXTRAPOLATION FROM LOW CLOUD BANDS FEEDING INTO THE CLOUD COVERED LLCC OBSERVED IN EIR IMAGERY. THIS IS SUPPORTED BY 041425Z AMSR2 91 GHZ AND 36 GHZ MICROWAVE IMAGES SHOWING A SLIGHTLY ELONGATED CIRCULATION CENTER WITH DEEP CONVECTION CONCENTRATED IN THE POLEWARD SEMI-CIRCLE. THE INITIAL INTENSITY IS BASED ON MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T3.0 (45 KNOTS) THAT ARE VALIDATED BY A 041600Z OBSERVATION FROM CREAL REEF REPORTING 42 KNOTS. UPPER LEVEL ANALYSIS INDICATES THAT THE CYCLONE IS NOW IN AN AREA OF UNFAVORABLE (20-30 KNOTS) NORTHERLY VWS THAT IS OFFSET BY EXCELLENT POLEWARD OUTFLOW. ALONG-TRACK SSTS REMAIN CONDUCIVE (27 TO 28 CELSIUS). THE SYSTEM IS TRACKING SLOWLY SOUTHEASTWARD ALONG THE PERIPHERY OF A NER EXTENSION TO THE NORTHEAST AND IS EXPECTED TO GRADUALLY WEAKEN DUE TO THE UNFAVORABLE VWS. AS 17P IS SHEARED FROM THE TOP DOWN, IT IS EXPECTED TO ENTER INTO A QUASI-STATIONARY (QS) STATE BEFORE RECURVING NORTHWESTWARD DUE TO THE STEERING INFLUENCE OF A 700 MB STR TO THE SOUTHWEST, WHICH WILL BECOME THE PRIMARY STEERING MECHANISM. AVAILABLE NUMERICAL MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT ON THE EVENTUAL EQUATORWARD U-TURN, BUT WITH NOTABLE DIFFERENCES IN TRACK SPEED. FOR THIS REASON THERE IS OVERALL LOW CONFIDENCE IN THE JTWC TRACK FORECAST, WHICH IS LAID JUST SLIGHTLY SLOWER AND WESTWARD OF MODEL CONSENSUS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 041800Z IS 14 FEET. NEXT WARNINGS AT 050300Z, 050900Z, 051500Z AND 052100Z.//