Severe Weather Warning : South Island Floods And Gales

ISSUED BY MetService AT 9:27 am 02-Jan-2013

Heavy rain for the west of the South Island, with significant spillover into the Canterbury headwaters. Severe gales for parts of Canterbury, Marlborough and the southern North Island.

CLICK HERE FOR LATEST SEVERE WEATHER WARNINGS

A very strong northwest flow covers much of the South Island and lower North Island ahead of an approaching front, bringing heavy rain and thunderstorms to the west of the South Island. This front should cross much of the South Island today and the southern North Island early Thursday, with winds and rain both easing after its passage. Until this time, further heavy rain is expected about Westland and the Southern Alps, with total amounts for this event possibly reaching 500 to 600mm in places, with significant spillover into the headwaters of the Canterbury Lakes and Rivers. This is a substantial amount of rain even for these areas. The rainfall warning also includes the ranges of Buller and northwest Nelson, where 120mm could fall during today (Wednesday). Rivers and streams are likely to rise rapidly in all these areas, including those in Canterbury and Otago that feed from the Divide. Surface flooding and slips are also possible.

The rain has eased in Fiordland and the Otago Headwaters and the warnings for these areas are now lifted.

In the east of the South Island and southern North Island, northwesterlies are reaching gale force in exposed places, with severe gale gusts of 120 km/h to 140 km/h possible about inland Canterbury, Marlborough, Wellington and Wairarapa south of Masterton until late today or early Thursday. A wind warning is now in place for Taranaki, Taihape, Wanganui and Manawatu (including the Kapiti Coast) for a brief period of severe gales overnight Wednesday into Thursday, when gusts could reach 120 km/h.

Winds of this strength have the potential to damage trees, powerlines and unsecure structures and can make driving difficult for tall sided vehicles, campervans, caravans and motorcycles.

The wind warning for Otago and Canterbury south of Fairlie is now lifted as the wind has eased in these areas.

HEAVY RAIN WARNING

AREA/S AFFECTED

Westland from the Glaciers southwards

FORECAST

Heavy rain is expected to continue until late this afternoon. In the 8 hours from 9am to 5pm Wednesday, expect a further 70 to 120mm of rain about the ranges on top of what has already fallen. 30 to 50mm of rain is likely near the coast. The heaviest falls are likely until early afternoon, when intensities could reach 25 to 40mm per hour, especially with any thunderstorms.

FREEZING LEVEL: About 2600 metres.

AREA/S AFFECTED

Westland between Amuri Pass/Ahaura River and the Glaciers

FORECAST

Heavy rain is expected through until this evening. In the 12 hours from 9am to 9pm Wednesday, expect a further 150 to 175mm of rain about the ranges on top of what has already fallen, but possibly 220mm more in some places. More than 60 to 80mm is possible near the coast from Greymouth southwards. The heaviest falls are likely until late afternoon or early evening when intensities could reach 25 to 40mm per hour, especially with any thunderstorms.

FREEZING LEVEL: About 2800 metres.

AREA/S AFFECTED

Headwaters of the Canterbury Lakes and Rivers

FORECAST

Heavy rain is expected through to this evening. In the 12 hours from 9am until 9pm Wednesday, expect a further 100 to 150mm of rain on the Divide on top of what has already fallen, with over 80mm likely within 25km east of the Divide. Note, in South Canterbury, the rain may ease three to four hours earlier. The heaviest falls are expected until late afternoon, when rates could reach 25mm per hour near the Divide, especially with any thunderstorms.

FREEZING LEVEL: About 2600 metres.

AREA/S AFFECTED

Northwest Nelson Ranges, the ranges of Buller and the Paparoa Range in North Westland

FORECAST

A period of heavy rain is expected today, accompanied by strong northwest winds. In the 15 hours from 9am to midnight Wednesday, 80 to 120mm of rain is possible about the ranges. The heaviest falls are likely late afternoon and early evening when intensities could reach 20mm per hour.

FREEZING LEVEL: About 3200 metres.

STRONG WIND WARNING

AREA/S AFFECTED

Inland Canterbury north of Fairlie

FORECAST

Northwest gales are expected in exposed places until late afternoon. From 9am until 5pm Wednesday, severe gale gusts of 120km/h are possible, with gusts of 140km/h likely about exposed parts of the Canterbury High Country.

AREA/S AFFECTED

Marlborough

FORECAST

Northwest gales are expected in exposed places through to Wednesday night, with severe gale gusts of 120 km/h possible between about midday and midnight today (Wednesday), especially about the Sounds and about and east of the Kaikoura Ranges.

AREA/S AFFECTED

Wellington and Wairarapa south of Masterton

FORECAST

Northwest gales are expected through to early Thursday morning. Between 9am Wednesday and 3am Thursday, severe gale gusts of 120 km/h are expected in exposed places, with possible gusts of 140 km/h Wednesday evening or night.

AREA/S AFFECTED

Taranaki, Taihape, Wanganui and Manawatu (including the Kapiti Coast)

FORECAST

North to northwest winds are expected to briefly reach severe gale in exposed places overnight Wednesday to Thursday. Between midnight Wednesday and 4am Thursday, gusts of 120 km/h are possible in a few places.

WARNINGS NO LONGER IN FORCE

HEAVY RAIN WARNINGS HAVE BEEN LIFTED FOR: Fiordland

The heavy rain has eased in most places. In a few areas, 30mm more may fall before midday.

HEAVY RAIN WARNINGS HAVE BEEN LIFTED FOR: Headwaters of the Otago Lakes and Rivers

The widespread heavy rain has now eased. However, convection this afternoon and evening may lead to a few localised falls of 30 to 40mm over a couple of hours anywhere in Otago.

STRONG WIND WARNINGS HAVE BEEN LIFTED FOR: Inland parts of Central and North Otago and Canterbury south of Fairlie

NEXT SEVERE WEATHER WARNING WILL BE ISSUED AT OR BEFORE 9:00 pm Wednesday 02-Jan-2013

© Scoop Media