1. TROPICAL CYCLONE 17P (IRIS) WARNING NR 029
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
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WARNING POSITION:
060600Z --- NEAR 19.4S 153.8E
MOVEMENT PAST SIX HOURS - 045 DEGREES AT 01 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
100 NM SOUTHEAST QUADRANT
130 NM SOUTHWEST QUADRANT
105 NM NORTHWEST QUADRANT
REPEAT POSIT: 19.4S 153.8E
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FORECASTS:
12 HRS, VALID AT:
061800Z --- 18.7S 153.4E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
095 NM SOUTHEAST QUADRANT
115 NM SOUTHWEST QUADRANT
065 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 330 DEG/ 05 KTS
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24 HRS, VALID AT:
070600Z --- 17.9S 152.9E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
095 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
015 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 345 DEG/ 05 KTS
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36 HRS, VALID AT:
071800Z --- 16.9S 152.6E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 010 NM NORTHEAST QUADRANT
070 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
010 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 345 DEG/ 06 KTS
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EXTENDED OUTLOOK:
48 HRS, VALID AT:
080600Z --- 15.8S 152.3E
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
040 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
005 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 345 DEG/ 06 KTS
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72 HRS, VALID AT:
090600Z --- 13.6S 151.6E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
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REMARKS:
060900Z POSITION NEAR 19.2S 153.7E.
TROPICAL CYCLONE (TC) 17P (IRIS), LOCATED APPROXIMATELY 480 NM EAST-
SOUTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED NORTHEASTWARD AT 01
KNOT OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC)
WITH THE REMAINING CONVECTION SHEARED 150NM TO THE SOUTHEAST. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A 060540Z
HIMAWARI VISIBLE SATELLITE IMAGE WHICH SHOWS THE LLCC. THE INITIAL
INTENSITY OF 40 KNOTS IS BASED ON A 060525Z SATCON ESTIMATE OF 40
KNOTS. THIS IS HEDGED SLIGHTLY ABOVE A PGTW DVORAK CURRENT INTENSITY
(CI) ESTIMATE OF T2.5 (35 KNOTS) WHICH IS UNDERESTIMATING WIND SPEEDS
DUE TO THE LACK OF CONVECTION. ENVIRONMENTAL ANALYSIS SHOWS MODERATE
(20 TO 25 KNOT) VERTICAL WIND SHEAR WHICH IS OFFSET BY EXCELLENT
POLEWARD OUTFLOW. SEA SURFACE TEMPERATURES REMAIN FAVORABLE, NEAR 29
DEGREES CELSIUS. DYNAMIC MODEL GUIDANCE CONTINUES TO COME INTO BETTER
AGREEMENT INDICATING A NORTHWARD TRACK. AS TC 17P TRACKS NORTHWARD IT
WILL MOVE INTO A MORE FAVORABLE WIND SHEAR ENVIRONMENT WHICH WILL
HELP TO MAINTAIN AN INTENSITY OF 40 KNOTS THROUGH TAU 24. MOST OF THE
MODEL GUIDANCE IS INDICATING THAT TC 17P WILL DISSIPATE BY TAU 72 BUT
NAVGEM CONTINUES TO INDICATE INTENSIFICATION BEYOND TAU 72.
THEREFORE, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK AND
INTENSITY. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 060600Z IS 15 FEET.
NEXT WARNINGS AT 061500Z, 062100Z, 070300Z AND 070900Z.
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