1. TROPICAL CYCLONE 17P (IRIS) WARNING NR 028
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:
060000Z --- NEAR 19.5S 153.7E
MOVEMENT PAST SIX HOURS - 045 DEGREES AT 05 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 - 080 NM NORTHEAST QUADRANT
140 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
REPEAT POSIT: 19.5S 153.7E
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FORECASTS:
12 HRS, VALID AT:
061200Z --- 18.9S 153.4E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
125 NM SOUTHEAST QUADRANT
115 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 335 DEG/ 04 KTS
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24 HRS, VALID AT:
070000Z --- 18.1S 153.0E
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: 330 DEG/ 06 KTS
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36 HRS, VALID AT:
071200Z --- 17.0S 152.4E
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
000 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 340 DEG/ 04 KTS
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EXTENDED OUTLOOK:
48 HRS, VALID AT:
080000Z --- 16.2S 152.1E
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/ 05 KTS
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72 HRS, VALID AT:
090000Z --- 14.3S 151.5E
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:
060300Z POSITION NEAR 19.3S 153.6E.
TROPICAL CYCLONE 17P (IRIS), LOCATED APPROXIMATELY 476 NM EAST-
SOUTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED NORTHEASTWARD AT 05
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY REVEALS AN EXPOSED LOW LEVEL CIRCULATION CENTER WITH
CONVECTION SHEARED APPROXIMATELY 90 NM TO THE SOUTHEAST. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE DUE TO THE EXPOSED LLCC.
THIS POSITION IS SUPPORTED BY A 060026Z GMI 89 GHZ MICROWAVE IMAGE
SHOWING BANDING WRAPPING INTO THE CENTER AND DEEP CONVECTION
ISOLATED TO THE SOUTHEAST. THE INITIAL INTENSITY OF 45 KNOTS IS
BASED ON THE 060000Z PGTW DVORAK FIX OF CURRENT INTENSITY (CI) T3.0
(45 KTS), ABOVE THE KNES FIX OF CI T2.5 (35 KTS), AND SUPPORTED BY A
38 KT OBSERVATION 70NM TO THE SOUTHEAST IN THE VICINITY OF THE
CONVECTION. ADDITIONALLY, THE INITIAL INTENSITY IS IN CLOSE
AGREEMENT WITH A 051944Z SATCON ESTIMATE OF 42 KTS. ENVIRONMENTAL
ANALYSIS SHOWS MODERATE TO HIGH NORTHWESTERLY VERTICAL WIND SHEAR
(20 TO 30 KNOTS) WHICH IS OFFSET BY EXCELLENT POLEWARD OUTFLOW. SEA
SURFACE TEMPERATURES REMAIN FAVORABLE, BETWEEN 27 AND 28 DEGREES
CELSIUS. TC 17P IS CURRENTLY TRACKING TO THE NORTHEAST IN AN
UNCERTAIN STEERING ENVIRONMENT BETWEEN A NEAR EQUATORIAL RIDGE TO
THE NORTH AND A MIDLEVEL RIDGE TO THE SOUTHWEST. TC 17P IS EXPECTED
TO TRACK TO THE NORTHWEST UNDER THE INFLUENCE OF THE MID LEVEL
STEERING FLOW AND GRADUALLY WEAKEN UNDER PERSISTENT MODERATE TO HIGH
VWS AND A FORMING UPPER LEVEL LOW, WHICH WILL SUPPRESS CONVECTION,
LEADING TO DISSIPATION AT 72 HOURS. OVER THE PAST SEVERAL RUNS,
NUMERICAL MODEL GUIDANCE HAS INDICATED AN IMMEDIATE TURN TOWARDS THE
NORTHWEST THAT HAS NOT YET MATERIALIZED. AS A RESULT, THE JTWC
FORECAST TRACK IS LAID TO THE RIGHT OF AND SLOWER THAN MODEL
CONSENSUS, AS THE TIMING WHEN TC 17P WILL MAKE THE EXPECTED TURN TO
THE NORTHWEST IS UNCLEAR. DUE TO THE UNCERTAINTY IN TRACK SPEED AND
WHEN TC 17P WILL TURN TO THE NORTHWEST, THERE IS OVERALL LOW
CONFIDENCE IN THE JTWC FORECAST TRACK AND INTENSITY. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 060000Z IS 16 FEET. NEXT WARNINGS AT
060900Z, 061500Z, 062100Z AND 070300Z.
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