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Severe Tropical Cyclone Evan (04P) Hits Samoa

22.5S 154.6W

December 17th, 2012 Category: Tropical Cyclones

Tropical Cyclone Evan (TC 04P) – December 17th, 2012

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Track of Tropical Cyclone Evan (TC 04P) - December 17th, 2012 © Univ. of Wisconsin

Track of TC 04P

Severe Tropical Cyclone Evan (RSMC Nadi designation: 04F, JTWC designation: 04P) is considered to be the worst tropical cyclone to hit the island nation of Samoa since Severe Tropical Cyclone Val.

The first cyclone of the 2012–13 South Pacific cyclone season, Evan developed from a tropical disturbance on December 9 north-northeast of Fiji. The storm moved east and impacted Samoa and American Samoa; Evan also hit the French islands of Wallis and Futuna and is currently active.

On December 9, the Fiji Meteorological Service’s Regional Specialized Meteorological Centre in Nadi (RSMC Nadi) started to monitor a weak tropical depression, that had developed within the South Pacific Convergence Zone (SPCZ), about 700 km (430 mi) to the northeast of Suva. Over the next two days, the depression gradually developed further in an area of low vertical windshear and favourable sea surface temperatures of about 28 – 30 °C (82 – 86 °F), as it was steered eastwards by an upper level ridge of high pressure.

At 1800 UTC on December 11, the United States Joint Typhoon Warning Center (JTWC) started to issue advisories on the system and designated it as Tropical Cyclone 04P, after 1-minute sustained winds had become equivalent to a tropical storm while the system’s low level circulation centre was rapidly consolidating. RSMC Nadi then reported early the next day that the system had become a category one tropical cyclone on the Australian tropical cyclone intensity scale and named it Evan, while located about 410 km (250 mi) to the west of Pago Pago on the American Samoan island of Tutuila.

Throughout December 12, Evan continued to be steered eastwards towards the Samoan islands by the upper level ridge, as it quickly intensified further with RSMC Nadi reporting at 1200 UTC that the system had become a category two tropical cyclone. At 1800 UTC the JTWC reported that the system had become equivalent to a category one hurricane on the Saffir-Simpson hurricane scale (SSHS) with 1-minute sustained windspeeds of 120 km/h (75 mph), while it was located about 40 km (25 mi) to the southeast of Apia, Western Samoa.

Over the next 12 hours the system developed a 17 km (11 mi) cloud filled eye on visible imagery, while the systems forward motion started to slow down as it entered a weak steering environment with the upper level ridge of high pressure to the north of the system weakened and a subtropical ridge of high pressure developed to the south of the system.

At 0600 UTC RSMC Nadi reported that Evan had become a category 3 severe tropical cyclone, as it passed over the island of Upolu. During that day the system continued to intensify as started to recurve towards the west, before at 1800 UTC the JTWC reported that Evan had reached its initial peak intensity of 185 km/h (115 mph), which made it equivalent to a category 3 hurricane on the SSHS. On December 16, Evan completed a cyclonic loop, and by December 17, the system strengthened into a Category 4–equivalent cyclone on the SSHS.

Tropical Cyclone Ului (20P) Expected to Make Landfall in Queensland, Australia

14.6S 152.5E

March 19th, 2010 Category: Tropical Storms

Tropical Cyclone Ului (20P) - March 16th, 2010

Tropical Cyclone Ului (20P) - March 16th, 2010

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Track of TC 20P - March 18th, 2010 © Univ. of Wisconsin

Track of TC 20P

Severe Tropical Cyclone Ului (20P) is one of the fastest intensifying tropical cyclones on record, strengthening from a tropical storm to a Category 5 equivalent cyclone within a 24 hour span.

Between 13 and 14 March, Cyclone Ului underwent an unusually explosive phase of rapid intensification. During a 24 hour span, the system intensified from a tropical storm to a Category 5 equivalent cyclone, tying Hurricane Wilma in 2005 for the fastest intensification of a system from tropical storm to Category 5.

According to the JTWC, maximum sustained winds increased from 100 km/h (65 mph) to 260 km/h (160 mph). They also estimated that the storm’s minimal central pressure had decreased from 982 mbar (hPa) to 918 mbar (hPa), a drop of 64 mbar (hPa), during this span.

Ului was first identified by the Fiji Meteorological Service (FMS) late on 9 March roughly 130 kilometres (80 miles) north of Hiw Island, Vanuatu. At this time, the system was classified as Tropical Disturbance 13F.

Early the following day, the system became sufficiently organized for the FMS to upgrade the disturbance to a tropical depression. Several hours later, the Joint Typhoon Warning Center (JTWC) also began monitoring the system. By this time, deep convection had developed around a low-level circulation and banding features had formed. A slow westward movement was expected as the depression was situated north of a subtropical ridge.

On 12 March, 13F was upgraded to Tropical Cyclone Ului. By early on 13 March, it was a category 2 cyclone. Later that day, Ului strengthened into a category 3, making it a severe tropical cyclone. The storm continued to strengthen throughout the day and that night it became a category 5.

Ului became the first category 5 South Pacific cyclone since Severe Tropical Cyclone Percy in February of 2005 but weakened to category 4 about the time it crossed the 160°E meridian. The system was predicted to restrengthen back into a category 5 as it moved away from an upper level low and Severe Tropical Cyclone Tomas, however 20P remained as a category 4 and had weakened to a category 3 system in the early hours of 18 March but is expected to restrengthen.

As a Category 5 cyclone, Ului passed through the southern Solomon Islands, causing severe damage on the islands of Rennell, Guadalcanal as well as Bellona province. Large swells produced by the storm washed away several homes along coastal areas. Flooding was also reported on several islands; however, officials confirmed that no fatalities resulted from the storm.

Maximum winds on the affected islands reached 120 km/h (75 km/h). On Rennell Island, initial reports stated that at least ten homes had been severely damaged or destroyed in several villages. Light to moderate damage was sustained on Makira and Guadalcanal, with at least two homes sustaining damage.

Unconfirmed reports of a large wave inundating several villages, washing away homes and overturning large boulders came from east Makira around 4:00 pm local time. Another village on the western side of Makira was reportedly inundated roughly five hours later. Later damage assessments made on Makira Island confirmed at least 13 homes were destroyed and several more were damaged. The most severe damage took place in Woau village where ten homes were destroyed.

After Cyclone Ului passed through the Solomon Islands, officials in Queensland, Australia began warning residents about the possibility of the storm making landfall in the region. Large swells produced by the system prompted lifeguards to close large areas of public beaches. These swells were anticipated to be the largest experienced along the Queensland coastline in the past decade and emergency management officials warned residents living along coastal areas that the waves would likely inundate low-lying regions.

On 18 March, new forecasts of the future track of Ului indicated that it would make landfall in Queensland. As a result, officials evacuated roughly 300 people from the islands of Heron and Lady Elliot, situated about 1,000 km (620 mi) off the Australian mainland. Residents along the Sunshine Coast were advised to prepare their homes for a possible Category 4 cyclone and stock up on non-perishable foods.

Later on 18 March, the Bureau of Meteorology is expecting that the cyclone will cross or near the Queensland coast, between Cardwell and Mackay, on 21 March as a category 3 cyclone. Several ports along the Queensland coastline were shut down for several days as large waves impacted the region. Transportation of coal and other raw materials was halted in these areas as well.