New Zealand's Auckland braces for ex-cyclone Gabrielle impact

Auckland Airport said airlines were announcing flight cancellations.

SYDNEY (Reuters) - Residents of New Zealand's biggest city were urged on Sunday to prepare for the impact of a storm that buffeted Australia's Norfolk Island overnight.

Gabrielle, downgraded to a sub-tropical low pressure system from a Category 2 cyclone, hit Norfolk Island on Saturday night, with its most destructive winds missing the island, before tracking to New Zealand, 1,460 kilometres (910 miles) south.

New Zealand's North Island and its largest city Auckland braced for the storm's full impact from Sunday night. Last month Auckland was hit by record rainfall that sparked floods and killed four people.

The city of 1.6 million was in line for a "full trifecta" of heavy rain, strong winds and storm surges, said Georgina Griffith, a spokeswoman for the nation's weather forecaster, MetService.

"Don't be fooled if you're not affected until Tuesday," she told reporters.

Wind and rain were spreading from the country's north, with a 140km per hour (87 miles per hour) wind gust reported on the country's North Island on Sunday afternoon, MetService said.

"Rainfall amounts over the next three days show that although things get going today, the bulk of the rain is expected on Monday," it warned, as authorities tipped rain of up to 40 mm (1.6 inches) on Monday.

Auckland Emergency Management said it was working to get 26 emergency shelters up-and-running in the city in time for the wild weather's arrival.

With Gabrielle closing in, Air New Zealand said it was cancelling multiple long-haul international fights on Monday, as well as Tasman and Pacific Island flights, and domestic services in and out of Auckland.

Auckland Airport said airlines were announcing flight cancellations in the "evolving situation", and encouraged people with travel booked to watch for updates.

Mayor Wayne Brown's office urged residents to prepare, including by tying down loose outdoor items and ensuring houses were clear of debris.

The storm was on track to lie off Cape Reinga at the North Island's north end on Sunday afternoon, after moving away from Norfolk Island, MetService said.

On Norfolk Island, which covers just over 34 square km (13 square miles) in the Pacific Ocean between New Caledonia and New Zealand, authorities said they were clearing debris and trees from roads and restoring power knocked out in the storm.

The island's roughly 2,000 residents, some descended from British sailors who mutinied on the HMS Bounty in the 18th century, had been "extremely fortunate" with the passage of the cyclone, authorities said.