WTPS32 PGTW 052100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE WARNING// RMKS/ 1. TROPICAL CYCLONE 17P (IRIS) WARNING NR 027 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 051800Z --- NEAR 20.4S 153.5E MOVEMENT PAST SIX HOURS - 090 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 040 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 - 085 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 115 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT REPEAT POSIT: 20.4S 153.5E --- FORECASTS: 12 HRS, VALID AT: 060600Z --- 19.9S 153.2E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 025 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 320 DEG/ 04 KTS --- 24 HRS, VALID AT: 061800Z --- 19.2S 152.6E MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 055 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 005 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 335 DEG/ 03 KTS --- 36 HRS, VALID AT: 070600Z --- 18.6S 152.3E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 000 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 335 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 071800Z --- 17.8S 151.9E 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 - 000 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 035 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 345 DEG/ 04 KTS --- 72 HRS, VALID AT: 081800Z --- 16.1S 151.4E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER --- REMARKS: 052100Z POSITION NEAR 20.3S 153.4E. TROPICAL CYCLONE 17P (IRIS), LOCATED APPROXIMATELY 433 NM NORTH OF BRISBANE, AUSTRALIA, HAS TRACKED EASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS AN EXPOSED LOW LEVEL CIRCULATION CENTER WITH DEEP CONVECTION SHEARED APPROXIMATELY 30 NM TO THE SOUTHEAST. THE INITIAL POSITION IS PLACED WITH MODERATE CONFIDENCE DUE TO THE SLIGHTLY ELONGATED AND OBSCURED NATURE OF THE LLCC OBSERVED IN THE EIR LOOP. THIS POSITION IS SUPPORTED BY A 051741Z SSMI/S 91 GHZ MICROWAVE IMAGE SHOWING CLOUD BANDING WRAPPING INTO THE CIRCULATION CENTER. THE INITIAL INTENSITY OF 45 KNOTS IS BASED ON A 051800Z DVORAK ESTIMATE FROM PGTW USING THE SHEAR METHOD. ENVIRONMENTAL ANALYSIS SHOWS MODERATE NORTHWESTERLY VERTICAL WIND SHEAR (20 TO 25 KNOTS) WHICH IS OFFSET BY EXCELLENT POLEWARD OUTFLOW. SEA SURFACE TEMPERATURES REMAIN FAVORABLE, BETWEEN 27 AND 28 DEGREES CELSIUS. TC 17P IS CURRENTLY IN ITS QUASI-STATIONARY (QS) STATE DUE TO A WEAK STEERING ENVIRONMENT. AS THE SYSTEM GRADUALLY WEAKENS DUE TO VWS, IT IS EXPECTED TO TRACK TO THE NORTHWEST UNDER THE INFLUENCE OF THE MID LEVEL STEERING FLOW BEFORE DISSIPATING BY TAU 72. DYNAMIC MODEL TRACK GUIDANCE REMAINS IN GOOD AGREEMENT ON POSITION BUT WITH SIGNIFICANT DIFFERENCES IN SPEED AS TC 17P EXITS ITS QS STATE. THE JTWC FORECAST TRACK IS LAID JUST WESTWARD AND SLOWER THAN CONSENSUS, FAVORING THE GFS AND ECMWF SOLUTIONS. DUE TO THE UNCERTAINTY IN TRACK SPEED, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK AND INTENSITY. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 051800Z IS 16 FEET. NEXT WARNINGS AT 060300Z, 060900Z, 061500Z AND 062100Z.//