MetService is urging Dunedin residents to be prepared for possible flooding over Labour Weekend, as a large area of low pressure looks to drop more heavy rain along coastal Otago.
Meteorologist Clare O’Connor said a large area of low pressure was expected to cover the South Island tomorrow, and heavy rain or showers were likely to affect many areas, with heavy snow about the South Island high country.
Most alpine passes will be affected snow - between 10cm and 40cm has been forecast for state highways including the Crown Range, the Lindis Pass (State Highway 8) and the Milford Road (SH94).
Heavy easterly or southeasterly rain was likely to fall about eastern South Island areas, from Canterbury to northern and eastern parts of Otago - including Dunedin.
It was also possible that easterly rain could reach warning criteria about southern Otago, Clutha, inland Southland and eastern Fiordland.
"There is a risk of some heavier falls of rain around there on Saturday, which could extend into Sunday as well," Ms O'Connor said.
"There’s a low that will form to the west, just off Fiordland, and that will push the weather eastward before pulling it all back around on to the southeast coast of the South Island.
"It’s difficult to say how much rain will fall at this stage, but given that your soil conditions down there are already saturated from recent rain, there may be more flooding."
Heavy rain warnings may be issued this morning, and she urged people to keep up to date with the forecasts, she said.
Care needed on Milford Road
The Milford Road in Southland reopened at 10am today after being closed since noon Wednesday due to a heightened risk of avalanche.
Though the avalanche risk is now low, care is needed on SH94 at the weekend, Milford Road Alliance advised.
"Forecasts are now indicating more snow than initially expected, down to 600 metres. Travel disruptions likely on Saturday from mid-morning."
Though today would be fine, heavy rain and snow were set to affect the area from tomorrow until Monday.
Heavy snow warning
Meanwhile, there is a high confidence that a heavy snow warning would be issued for the Canterbury High Country, the Southern Alps and the Westland ranges for heavy snowfalls above about 500m.
It was also possible snowfall could affect parts of inland Otago and a heavy snow warning may be required for snow above 500m.
On Sunday, the large area of low pressure was expected to remain over the South Island, and it was possible the heavy rain would continue to affect South Canterbury and eastern Otago on Sunday, requiring a further heavy rain warning.
By Monday, the low should have weakened and moved out east of New Zealand, leaving much of Otago and Southland with showers and light winds.
Ms O’Connor said if people were travelling out of town this weekend, they should drive to the conditions, allow extra time to get there, avoid travelling at night, and watch for surface flooding, slips and fallen trees or branches.
"Also, before you leave home, make sure your house is prepared for heavy rainfall.
"Make sure your drains and gutters are clear, and make sure your house is ready for severe weather."
Road warnings
MetService late this morning issued road snowfall warnings for most of the alpine passes in the South Island.
Arthurs Pass (SH73)
Valid from 2am to 6pm on Saturday.
Snow expected from early in the morning until the evening. Some 20cm to 40cm may accumulate on the road above 600 metres.
Porters Pass (SH73)
From 2am to 6pm on Saturday.
Snow expected from early in the morning until the evening. Ten to 30cm may accumulate on the road above 600 metres.
Haast Pass (SH6)
From 2am to 6pm on Saturday.
Snow is expected on the road mainly from the summit southwards. Two to 5 cm may accumulate on the road above 500 metres.
Lindis Pass (SH8)
From 3am to 8pm on Saturday.
Snow expected from early in the morning until the evening. Some 10cm to 20cm may accumulate on the road above 500 metres.
Crown Range Road
From 3am until midnight on Saturday
Snow expected to fall about the road from early on Saturday morning and 20cm to 30cm may accumulate about the road above 500 metres.
Milford Road (SH94)
From 4am until midnight on Saturday.
Snow expected from early in the morning until evening. Some 15cm to 25 cm may accumulate on the road above 500 metres.
