1. TROPICAL CYCLONE 17P (IRIS) WARNING NR 026
01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
051200Z --- NEAR 20.3S 153.0E
MOVEMENT PAST SIX HOURS - 135 DEGREES AT 01 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 - 075 NM NORTHEAST QUADRANT
145 NM SOUTHEAST QUADRANT
130 NM SOUTHWEST QUADRANT
075 NM NORTHWEST QUADRANT
REPEAT POSIT: 20.3S 153.0E
---
FORECASTS:
12 HRS, VALID AT:
060000Z --- 20.0S 152.6E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
135 NM SOUTHEAST QUADRANT
130 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 325 DEG/ 03 KTS
---
24 HRS, VALID AT:
061200Z --- 19.5S 152.2E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
155 NM SOUTHEAST QUADRANT
135 NM SOUTHWEST QUADRANT
020 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 340 DEG/ 04 KTS
---
36 HRS, VALID AT:
070000Z --- 18.8S 151.9E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
100 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 335 DEG/ 03 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
071200Z --- 18.2S 151.6E
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 - 025 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 340 DEG/ 04 KTS
---
72 HRS, VALID AT:
081200Z --- 16.7S 151.1E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
---
REMARKS:
051500Z POSITION NEAR 20.2S 152.9E.
TROPICAL CYCLONE (TC) 17P (IRIS), LOCATED APPROXIMATELY 438 NM NORTH
OF BRISBANE, AUSTRALIA, HAS TRACKED SOUTHEASTWARD AT 01 KNOT
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS THAT CONVECTION TO THE SOUTH OF THE LOW LEVEL CIRCULATION
CENTER (LLCC) ASSOCIATED WITH TC 17P HAS PERSISTED. THE INITIAL
POSITION IS BASED ON A 051057Z METOP-A ASCAT IMAGE SHOWING A DEFINED
BUT SLIGHTLY ELONGATED CIRCULATION. THE INITIAL INTENSITY OF 45 KNOTS
IS BASED ON THE AFOREMENTIONED ASCAT IMAGE SHOWING WINDS TO THE SOUTH
OF THE LLCC REACHING 45 KNOTS, A 050830Z SATCON ESTIMATE OF 47 KNOTS,
AND A PGTW DVORAK ESTIMATE OF T3.0 (45 KNOTS). ENVIRONMENTAL ANALYSIS
SHOWS MODERATE VERTICAL WIND SHEAR (20 TO 25 KNOTS) WHICH IS OFFSET
BY EXCELLENT POLEWARD OUTFLOW AND MODERATE EQUATORWARD OUTFLOW. SEA
SURFACE TEMPERATURES REMAIN FAVORABLE, BETWEEN 28 AND 29 DEGREES
CELSIUS. TC 17P WILL GRADUALLY DECREASE IN INTENSITY TO 40 KNOTS BY
TAU 24 AND 35 KNOTS BY TAU 48. DYNAMIC MODEL TRACK GUIDANCE IS NOW IN
BETTER AGREEMENT BUT THE STEERING PATTERN AROUND TC 17P REMAINS VERY
WEAK. GFS SHOWS TC 17P WILL TRACK NORTHWARD AND DISSIPATE BY TAU 36
WHILE NAVGEM IS INDICATING THAT TC 17P WILL WEAKEN BUT THEN BEGIN TO
INTENSIFY BY TAU 96. THE JTWC FORECAST FAVORS THE GFS SOLUTION AND
CURRENTLY HAS TC 17P DISSIPATING TO 30 KNOTS BY TAU 72. OVERALL,
THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK AND INTENSITY.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 051200Z IS 15 FEET. NEXT WARNINGS
AT 052100Z, 060300Z, 060900Z AND 061500Z.
https://icons.wunderground.com/data/...01817_5day.gif