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Somerset Squall

Severe Tropical Cyclone Evan

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The first tropical cyclone of the South Pacific season has formed 290 miles west of Pago Pago, American Samoa, and about 450 miles northeast of Nadi, Fiji. Tropical Cyclone 04P (numbered 4 as it is the fourth tropical cyclone to form this season in the Southern Hemipshere, the first three were in the South Indian Ocean), has sustained winds of 35kts currently. The LLC is well defined, and is flanked by formative banding. 04P is in a very favourable environment for strengthening, with warm sea surface temperatures, low shear and excellent outflow. This means that 04P has the potential to rapidly intensify over the next few days. 04P is forecast to move eastwards along the south side of a ridge to the north during this time, so American Samoa should be very wary of this potentially dangerous system. Motion should reverse to the southwest in 4 days time as a ridge to the southeast takes control of steering influence, but this is not likely to occur in time to stop 04P affecting American Samoa.

sh0413.gif

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04P has become Tropical Cyclone Evan, with sustained winds now at 40kts. Evan is still expected to intensify over the coming days in the highly favourable environment. After affecting American Samoa, the reversed motion to the southwest will mean Evan is likely to affect Fiji later on, despite the fact thatEvan is currently moving away from here.

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I doubt it will make it that far as it is so far out in the South Pacific at the moment. Evan should recurve south before going anywhere near Australia IMO

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Evan has strengthened further today, with sustained winds now at 50kts. The cyclone has formed a central dense overcast feature, a sign of a healthy and maturing system. Evan is nearing American Samoa, and is lashing the area with flooding rains. An eye is expected to soon develop, as shear remains light and outflow impressive- allowing for for fairly quick intensification over the next day or so.

post-1820-0-18340000-1355338975_thumb.jp

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Evan is strengthening rapidly. Intensity is up at 65kts, cat 1 on the SS scale. An eye is appearing in the central dense overcast, and looks to be clearing out. Evan will probably continue to rapidly strengthen overnight, as the upper level environment remains highly conducive, along with the very warm sea temps in the area.

Satellite image, showing the development of an eye just south of Amercian Samoa, which is being lashed right now by Evan:

post-1820-0-80136300-1355351152_thumb.jp

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Evan continues to strengthen and now has sustained winds of 80kts, the high end of cat 1 on the SS scale. The cyclone has started to slow as the ridging to the north weakens. Evan will only move very slowly over the next day as the steering influence gradually shifts to a building ridge to the southeast. This is bad news for Samoa, as it will prolong the rains here.

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Evan has strengthened further to 90kts, cat 2 on the SS scale, and has been upgraded to a Severe Tropical Cyclone by Fiji Met. Evan retains a small eye which remains well defined. Samoa continues to be pounded by the system, which has moved little over the last 12hrs. The ridge to the southeast is slowly building and will eventually shift Evan west-southwestwards. The cyclone then looks to be on a collision course with Fiji, which is concerning given that Evan could be a 100-115kt cyclone at this time.

sh0413.gif

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Evan continues to intensify and is now a cat 3 on the SS scale, with sustained winds now at 100kts. Could easily make cat 4 soon IMO.

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Evan has killed 3 people in Samoa, and caused extensive damage. Evan continues to bring heavy rains here, but is finally moving to the west away from the country. Intensity remains at 100kts currently, but Evan is expected to resume strengthening soon, and JTWC expect a peak of 115kts prior to the severe cyclone nearing Fiji. Track forecasts have shifted slightly north to account for Evan looping northwards in instead of southwards. Fiji still need to be very wary of Evan nonetheless.

From Wikipedia:

On the island of Samoa, preparations for Evan started on December 12, with some people boarding up their homes. The Samoa Meteorology Division of the Ministry of Natural Resources and Environment placed Samoa under a hurricane watch.[14] This continued into December 13, when the cyclone struck, causing widespread damage in the capital, Apia. Many of the roads were blocked by flood waters and downed banana trees. Evan also caused damage to the airport in Apia, where the departures lounge collapsed, forcing its closure.[15] Wind gusts as high as 175 km/h (130 mph) were reported. The storm destroyed houses and caused almost complete failures in the power and water supply systems.[16] At least three deaths were reported after the storm, including two children who were in low-lying areas and drowned to death.[17] [18] Evan was considered the worst cyclone to hit Samoa in 20 years.[19]

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New Zealand? Auckland? What is the history of this region about tropical cyclones?

sp201204_5day.gif

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Evan is strengthening rapidly. Intensity is up at 65kts, cat 1 on the SS scale. An eye is appearing in the central dense overcast, and looks to be clearing out. Evan will probably continue to rapidly strengthen overnight, as the upper level environment remains highly conducive, along with the very warm sea temps in the area.

Satellite image, showing the development of an eye just south of Amercian Samoa, which is being lashed right now by Evan:

No, no, you've got your geography all wrong! American Samoa was relatively unaffected by this. That image shows the eye south of the nation of Samoa. American Samoa is way off to the east of there.

New Zealand? Auckland? What is the history of this region about tropical cyclones?

sp201204_5day.gif

They always undergo extratropical transition once approaching 30S. Very rare exceptions include Wilma from a few years ago, which was still officially classified as a TC as far south as 34S/35S.

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No, no, you've got your geography all wrong! American Samoa was relatively unaffected by this. That image shows the eye south of the nation of Samoa. American Samoa is way off to the east of there.

Oops, yes my geography isn't great for this part of the world. Thanks for correcting my mistake.

Evan has remained in a nearly steady state since I last posted. Intensity has increased slightly to 105kts. Evan retains a solid central dense overcast with a cloud filled eye. Evan could strengthen a little more as it moves just north of Fiji, and cat 4 on the SS scale cannot be ruled out. Slow weakening should begin beyond 24hrs as Evan moves into increased shear.

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Evan has strengthened to 115kts, making it a cat 4 on the SS scale. Evan is battering Fiji as the system's centre closes in on the north side of the country. Scary image for Fiji

post-1820-0-45270300-1355694581_thumb.jp

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Evan peaked at 125kts last night but has weakened back to 115kts as the cyclone interacts with the west coast of Fiji. As Evan moves southwards over the coming days, it'll weaken further due to increasing shear and decreasing sea temps along track.

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Fiji hammered by severe cyclone, no deaths reported

More than 8,000 people, including foreign tourists, were evacuated to emergency shelters as Fiji was battered by a severe tropical cyclone, with winds topping 230kmh (140 mph) and floods damaging homes and resorts.

There were no reports of casualties as Tropical Cyclone Evan roared over the Pacific island nation on Monday, uprooting palm trees, tearing roofs off buildings and blowing down power lines.

A category four storm, the second highest level, when it hit Fiji, Evan had weakened and moved about 160km (100 miles) south of the main island of Viti Levu by Tuesday morning, the Fiji Metrological Service said. The storm was forecast to weaken further as it headed into cooler southern waters.

Cyclone Evan killed at least four people in the islands of Samoa last week before setting its sights on Fiji, which relies on tourism and sugar exports.

http://www.reuters.com/article/2012/12/17/us-fiji-cyclone-idUSBRE8BG00S20121217

201204P.png

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Evan is no longer a tropical cyclone. Shear of over 50kts, coupled with cold sea temps north of the north island of New Zealand has killed Evan.

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