Heavy rain and strong winds are expected over much of New Zealand from tonight, prompting warnings of flooding in the South Island.
Severe Weather Warnings have been issued for most of the South Island and central North Island with heavy rain and strong northwest winds expected in Westland, Fiordland, Southland and the headwaters of the Otago and Canterbury lakes and rivers.
Gale force winds are also forecast for Otago, Canterbury, Marlborough, Wellington and Wairarapa.
The severe weather is being caused by a front from the Tasman sea which is expected to intensify as it approaches New Zealand tonight.
MetService has issued a severe weather warning for rain on the Southern Alps. Some 300mm of rain is predicted to fall in the 24 hour period from this evening in the same catchment areas of the Southern Alps that were drenched early last week.
The deluge has prompted Environment Canterbury to warn people of the dangers of rising levels in the South Canterbury rivers and lakes.
"While lake levels have now mostly peaked or are receding after the deluge at New Year's, there is still an excess of water in the lake system and many of the rivers in the Upper Waitaki catchment remain at higher than normal flows," says Chris Fauth, Environment Canterbury's Duty Flood Controller for the Southern Region.
The predicted rain is also expected to cause a significant increase in flow in the Rangitata River.
"All campers, fisherman and recreational users of both the Waitaki and Rangitata catchments need to be aware of the potentially worsening situation and alter the way they camp and use the lake and rivers accordingly," he said.
Regular holiday makers, farmers and other landowners near the South Canterbury alpine rivers are also encouraged to watch river flows, he said.
Fauth said while last week's flood event caused no major river breakouts and little out-of-river damage on the Rangitata, the high flow caused significant damage to in-river flood protection works, including washing vegetation from river berms, erosion of riverbanks and movement and deposition of river gravel.
"The damage to flood protection works has left parts of the river, including the South Branch Rangitata entry point, more vulnerable to further high flows."
People on the plains should also stay alert, even if the weather was fine, because rivers could still become unsafe as floodwaters flowed rapidly downstream.
Genesis Energy has indicated that the level of Lake Tekapo is
likely to continue to rise over this same period, and that they
will start spilling water into the Tekapo River in the next
River and lake levels monitored
Otago Regional Council flood managers say they are closely
monitoring river and lake levels, following Metservice's
ORC flood manager Matt Hickey said the predicted heavy rainfall would cause river and lake levels to rise in the Wakatipu, Wanaka, and Hawea lakes areas.
People camping and tramping in these areas, and in the
Manuherikia River area, are advised to take care and be
mindful of rising lake and river levels.
Predicted rainfall in South Otago on Wednesday night, particularly in Pomahaka, has the potential to significantly increase flows in the already-high lower Clutha River, flood managers say.
Farmers in the lower Clutha are advised to move stock and machinery away from low-lying areas.
MetService says the heaviest rain is likely to fall in Westland tomorrow where up to 350mm could accumulate in the ranges south of Otira during the day.
Meanwhile, Wellington and inland areas of Canterbury are expected to experience the most severe winds where gusts of 140km/h are likely.
Winds of this strength have the potential to topple trees and power lines and damage unsecured structures.
Meanwhile, State Highway 94 will be closed for the next 24 hours as heavy rain is forecast to hit the area tonight, the NZ Transport Agency reports.
The highway, which connects Gore with the Milford Sound, will close to all traffic at 7pm tonight, and will remain closed all day tomorrow.
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