Wednesday 18 January 2017

Extreme weather in New Zealand

A ‘weather bomb’ to hit New Zealand later today

MetService New Zealand, via Facebook

The 'bomb low', which means a rapidly deepening low pressure centre, is currently in a juvenile phase out in the Tasman. It sits under the polar exit of a jet stream, which enables the rapid deepening. This, combined with a strong boundary between warm and cold air, give it the energy required to start to rotate and deepen into a bomb low.

Rain on a windscreenAlthough the low centre is not going to reach New Zealand until around 10pm tonight, strong winds and rain ahead of it are already affecting the West Coast of the South Island. These spread north through the day to central NZ, with a clutch of warnings and watches. Check for more.

Apologies for the wrong date on the image, it is from 8:10am today, 18/1/2017!

Heavy rain, gales on way

Trolley buses in Wellington have been cancelled as the Capital battens down the hatches for the weather bomb hitting New Zealand on Wednesday.

Services are being replaced by diesel buses, Metlink says, and it is not expecting any major disruptions to its rail timetable.
Severe gales from a low-pressure weather system barrelling towards New Zealand could lift roofs, cause surface flooding and make travel dangerous, MetService warns.
The rain has already started on the West Coast as a preceding front begins to make its way north.
Western parts of central New Zealand, particularly Westland, can expect to be inundated with heavy rain between Wednesday night and Thursday morning.
A warning is in place for Westland, Buller, the Nelson ranges and the Headwaters of the Canterbury lakes and rivers.
Up to 400mm of rain is expected in Westland where a severe weather warning is in place, with significant spill-over into Canterbury lakes and rivers likely.
Residents in Buller and the Nelson ranges have also been told to expect up to 200mm overnight on Wednesday and into Thursday.

Blustery conditions will turn severe and possibly damaging over much of central New Zealand during the same period, the weather experts have forecast.

Rain getting going on the West Coast with the odd thunderstorm, and some spreading across to the east too. Check
At Castlepoint on the east coast of the North Island, gusts have already reached 118km/h with the worst yet to come. 
Wairarapa, Wellington, Marlborough and Canterbury north of Ashburton can expect northwest gales gusting up to 160km/h from Wednesday afternoon.

Warning for gusts>150km/h Weds evening, but how windy is that? Warnings issued when gusts >110km/h, so this is an exceptional event. ^TA

8:07 PM - 17 Jan 2017

"Winds of this strength can bring down trees and powerlines, damage unsecured structures, lift roofs and make travel hazardous," MetService said.
Southland, Clutha, Dunedin, Fiordland, Otago headwaters, Tararua ranges and Mt Taranaki could also expect 70mm of rain in 12 hours between Wednesday afternoon and Thursday morning.

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