Evan's last act may be miserable Christmas

20:00, Dec 22 2012
Cyclone Evan
BEARING DOWN: Cyclone Evan.

One of the most powerful storms seen in the South Pacific is threatening to make it a wet and windy Christmas for many Kiwis.

Remains of Cyclone Evan, which killed 15 people and caused $160 million damage in Samoa, inflicted severe damage on the French islands of Wallis and Futuna, and then Fiji, is forecast to be 500km north of Auckland today, heading into the Tasman Sea. Metservice has issued a severe weather watch for much of the North Island.

The heaviest rainfall will occur when the winds over northern New Zealand are from the east-northeast, which is overnight tonight and into tomorrow.

Northland faces especially heavy rain, but the north of Auckland, the north of Coromandel, the far east of the Bay of Plenty and Gisborne should also be ready to batten down the hatches.

On Tuesday - Christmas Day - rain is expected over much of the North Island, but the South Island may get away with just some rain in the west and some drizzle about the Canterbury and Otago coast.

By the time it's over, Evan will have clocked over 5500km and at one stage near Fiji it became a category five hurricane - the strongest on the scale.

Metservice said the ex-cyclone will track west and by the middle of Christmas Day will be 400km west of Northland. Over Boxing Day Evan will loop back south-eastward toward Taranaki, decaying off New Plymouth on Thursday.

The Metservice warns "old tropical cyclones are not to be underestimated" and said Evan was far from a spent force.

Although cyclones are normally good for surfers, with Evan producing 3m-5m ocean swells, the winds over beaches are not expected to be conducive to good surf.

Evan was declared a cyclone on December 13, prompting region-wide warnings.

Scientists are debating whether they could have made the call a day earlier as a Tropical Rainfall Measuring Mission (TRMM) satellite passed over the depression a day before and saw an eye-like structure in the system. An earlier warning could have made a big difference in Samoa, as most of the dead were fishermen caught at sea over December 13-14.

As Evan came in over Fiji, TRMM found "hot towers" on the edge of the eye and up to 17 km above sea level. Scientists had thought such high towers were unlikely over the ocean, as the sea has a roughly constant temperature, whereas land warms up during the day.

"During the first 10 years of the TRMM mission, only five thunderstorm cells as tall as the one seen in cyclone Evan were observed in South Pacific tropical cyclones," Nasa said.

It so rare they suggest such towers deserve their own nickname. "To distinguish them from run-of-the-mill hot towers, one can call these cells 'titans', 'super towers', or just extremely tall."

Evan was the first named cyclone of the 2012-13 South Pacific season. The next one will be Freda followed by Garry, Heley, Ian, Kofi, Lusi and Mike.


Auckland Now