Severe weather on the way

23:11, Dec 31 2013

Severe weather is on its way, and MetService is warning about the possibility of flash flooding, gales and thunderstorms across the country.

A complex trough over the Tasman Sea was expected to cross the country today, with rain or showers likely for much of the country.

Thunderstorms were possible in many places, with a high risk in northern Westland, Buller, Nelson and the Marlborough Sounds, bringing heavy rain and hail.

The most persistent heavy rain was expected about Buller and the ranges of northern Westland, where 70 to 100mm may accumulate.

A burst of heavy rain was also expected about the hills of eastern Nelson and western parts of the Marlborough Sounds, where 50 to 70mm may accumulate over six hours.

The front was expected to move through the lower North Island this afternoon, and could become increasingly unstable as it reaches the upper North Island.

There was a threat of one or two storms becoming severe, producing heavy downpours and a small tornado, but at this stage the risk was low.

There was also a moderate risk of isolated thunderstorms in South Canterbury, North Otago and Dunedin, with heavy rain, hail and a low risk of a funnel cloud or small tornado, MetService said.

Another active front is expected to approach the South Island tomorrow.

This would cause gale northwesterlies and rain, with the heaviest rain expected about Fiordland, Westland and the Alps, and affecting the Otago and Canterbury headwaters.

Rainfall of 150 to 200mm was expected about Westland and Fiordland.

In addition, northwesterlies were expected to rise to severe gale about inland parts of Southland, Otago and Canterbury late tomorrow, with gusts up to 140km/h about exposed parts of Canterbury.

MetService advised that heavy rain was likely to cause streams and rivers to rise rapidly, with flash flooding possible.

Winds could bring down trees and power lines, damage insecure structures and make driving hazardous for motorcycles and high-sided vehicles, MetService warned.


Fairfax Media