APCEDI Alert SP/FJ Cyclone Vaianu (TD12F) #2-2006: Cyclone Vaianu forms near Vava'u Group, Threatens Central and Southern Tonga

The RSMC-Nadi Tropical Cyclone Centre and the Joint Typhoon Warning Centre are issuing guidance on Cyclone Vaianu, formally Tropical Depression 12F.

Cyclone Vaianu formed last night northwest of the Vava'u Group. It is currently at Tropical Storm Strength and is expected to slowly intensify over the next 24 hours.

Cyclone Vaianu is located about 150 kilometres west-northwest of Vava'u or about 220 miles north-northwest of Ha'apai, and is moving . Vaianu is moving south-southwest at about 07 knots (13 km/h) and expected to curve southwest. Given Vaianu's forecast track to the west of the main islands and Vaianu's small size, it is likely that only minor damage and flooding could occur throughout much of the Vava'u, Ha'apai and Nomuka Groups for the most part. However, the western most islands in the Groups such as Late (Vava'u), Kao and Tofua (Ha'apai) and Fonuafo'ou and Hunga Tonga (Nomuka) should be particularly alert as the centre of Vaianu will be closest to these islands. Tonga's main island of Tongatapu needs to closely watch this storm as long term forecasting shows it curving southeast, but still passing to the west of the main island.

All interests in Tonga, Niue, and the Cook Islands should closely monitor the progress of this storm, and undertake any actions as advised by the local authorities. Although the storm is moving away from Wallis and Futuna, Fiji and Samoa, all interests should maintain vigilance due to continuing rough seas, winds and heavy rains.

CURRENT ADVISORIES AND WARNINGS

TONGA
A GALE WARNING REMAINS IN FORCE FOR VAVAU GROUP, HAAPAI GROUP AND NOMUKA GROUP.
A TROPICAL CYCLONE ALERT REMAINS IN FORCE FOR SOUTHERN TONGA.
A STRONG WIND WARNING REMAINS IN FORCE NIUAS AND SOUTHERN TONGA.

SAMOA
WIND ADVISORY IN FORCE FOR SAMOA
FLOOD ADVISORY REMAINS IN FORCE
LANDSLIDE ADVISORY REMAINS IN EFFECT

NIUE
A STRONG WIND WARNING REMAINS IN FORCE FOR NIUE.

FIJI
A STRONG WIND WARNING IS NOW IN FORCE FOR THE SOUTHERN LAU GROUP.
A STRONG WIND WARNING IS NOW IN FORCE FOR LAU WATERS, KORO SEA, KADAVU AND VATU-I-RA PASSAGES.

WALLIS AND FUTUNA
A STRONG WIND WARNING REMAINS IN FORCE FOR WALLIS AND FUTUNA WATERS.

AMERICAN SAMOA
SMALL CRAFT ADVISORY
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From the RSMC-Nadi Tropical Cyclone Centre

Tropical Disturbance Advisory Number A7 issued from RSMC NADI
Feb 11/1951 UTC 2006 UTC.

Tropical Cyclone VAIANU [990hPa] centre was located near 17.8 South 175.4 West at 111800 UTC. Position poor and based on MTSAT/EIR with animation and peripheral surface reports. Repeat position 17.8S 175.4W at 111800 UTC. Cyclone moving southsouthwest at about 07 knots and expected to curve southwest. Cyclone intensifying. Maximum 10-minute average winds estimated at 40 knots close to the centre increasing to 45 knots in the next 6 to 12 hours. Expect winds above 33 knots with 60 nautical miles of centre.

TC Vaianu's overall organisation continues to improve despite 10 to 20 knots shear aloft. CIMMS indicates that the cyclone is moving into a decreasing shear zone and the increased equatorward outflow should maintain a positive growth curve for the system. LLCC still difficult to locate and placed near the southern edge of deep convection. The system lies just south of 250-hPa outflow in a diffluent region. SST in the area is about 29-30C. Dvorak analysis based on .60 wrap on log10 spiral gives DT=MET=PT=3.0, yielding T3.0/3.0/D1.0/24hrs. The system is steered southwest by a mid-level ridge to east for the next 24 hours and is expected to curve southeast beyond 48 hours in response to an approaching broad upper trough from the west. Global models agree on a southwest track with further intensification in the short term.

FORECAST:
12hrs valid at 120600 UTC near 18.9S 176.3W mov SSW at 07kt with 45 kt close to the centre.
24hrs valid at 121800 UTC near 19.6S 176.9W mov SW at 05kt with 55 kt close to the centre.

OUTLOOK:
36hrs valid at 130600 UTC near 20.3S 176.7W mov SSE at 05kt with 60kt close to the centre.
48hrs valid at 131800 UTC near 21.3S 176.3W mov SSE at 06kt with 60kt close to the centre.

The next Tropical Disturbance Advisory on Tropical Cyclone VAIANU will be issued around 120200 UTC.
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The TONGA FORESCAST from RSMC-Nadi Tropical Cyclone Centre


Special Weather Bulletin Number Eight for Tonga on TROPICAL CYCLONE VAIANU issued from RSMC NADI
Feb 11/2055 UTC 2006 UTC.

TROPICAL CYCLONE WARNING.

A GALE WARNING REMAINS IN FORCE FOR VAVAU GROUP, HAAPAI GROUP AND NOMUKA GROUP.
A TROPICAL CYCLONE ALERT REMAINS IN FORCE FOR SOUTHERN TONGA.
A STRONG WIND WARNING REMAINS IN FORCE NIUAS AND SOUTHERN TONGA.

Tropical Cyclone VAIANU [990hPa] centre was located near 17.8 South 175.4 West or about 95 miles westnorthwest of Vava'u or about 135 miles northnorthwest of Ha'apai at 111800 UTC. Position poor and based on MTSAT/EIR with animation and
peripheral surface reports. Repeat position 17.8S 175.4W at 111800 UTC. Cyclone moving southsouthwest at about 07 knots and expected to curve southwest. Cyclone intensifying. Maximum 10-minute average winds estimated at 40 knots close to the centre increasing to 45 knots in the next 6 to 12 hours. Expect winds above 33 knots with 60 nautical miles of centre.

On its current track, the cyclone is expected to lie 115 miles northwest of Ha'afeva or 120 miles west of Vava'u at 120300 UTC and 110 miles northwest of Ha'afeva at 120600 UTC.

FOR VAVA'U GROUP, HA'APAI GROUP, NOMUKA GROUP, KOTU GROUP:
Expect damaging gale force winds with average speeds 30 to 35 knots and momentary gusts of 55 to 60 knots about Vava'u Group. North to northeast winds 25 knots gusting to 45 knots about Ha'apai Group, Nomuka group, Kotu group, increasing to damaging gale force with average speeds of 30 to 35 knots and momentary gusts up to 60 knots within the next 6 to 12 hours. Periods of heavy rain and with some squally thunderstorms. Flooding including sea flooding of low-lying coastal areas expected. Very rough to high seas. Damaging heavy swells.

FOR SOUTHERN TONGA:
East to southeast winds 20 to 25 knots with gusts to 35 knots. Winds expected to gradually turn north to northeast and increase to damaging gale force with average speeds of 35 to 40 knots and momentary gusts of 50 to 60 knots in the next 24 to 36 hours. Some rain, becoming frequent and heavy tonight with squally thunderstorms. Flooding including sea flooding of low-lying coastal areas expected. Very rough to high seas. Damaging heavy swells developing.

FOR NIUAFO'OU AND NIUATOPUTAPU:
West to northwest winds 25 to 30 knots, gusting to 45 knots. Rain, heavy at times with squally thunderstorms. Flooding of low lying areas, including sea flooding of coastal areas likely. Rough to very rough seas. Heavy northwest swells.

THE FOLLOWING INFORMATION IS PROVIDED ESPECIALLY FOR MARINERS:
Expect sustained winds of 40 knots close to Vaianu's centre increasing to 45 knots in the next 6 to 12 hours. Expect winds over 33 knots within 60 miles of centre. High seas and heavy swells.
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APCEDI will continue to monitor the progress of this system.

Kevin Vang
APCEDI Coordinator
http://www.afap.org/apcedi/

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