A weather front headed north up the West Coast at present is expected to loop over the Alps and come down into Central and North Otago and possibly coastal areas, from mid-Saturday through to a peak about midnight on Saturday, says ORC’s General Manager Science and Resilience, Tom Dyer.

“While the weather has been relatively benign around most of Otago the past few days, heavy rain is expected tomorrow, which could cause ponding or minor surface flooding in some areas. There is also unseasonal snow forecast to above 600 metres inland, but there’s potential could lower to around 400m, or lower in some areas,” Mr Dyer says.

At noon, a MetService Heavy Snow Warning remains in place for the Queenstown Lakes District and Central Otago.

Rain in Otago during Saturday to midnight is expected to total 30-50mm, falling “steadily” at around 5mm per hour, which that itself is unlikely to trigger alerts, but Mr Dyer says the still sodden ground from the 3-6 October flooding in coastal Otago and some areas inland is the concern.

“The rainfall is likely sheet off the land directly into waterways, which then poses the problem of accumulation and possible surface flooding,” he says.

If travelling tomorrow, people should expect to drive to likely deteriorating conditions and should consider carrying snow chains, with possible disruptions to journeys.

He says while most Southern rivers had already peaked during the past 36 hours from the first front, the second front tomorrow could again see rivers and streams, which could pose dangers for people looking to ford waterways.

“If in any doubt, don’t attempt to cross swollen rivers,” Mr Dyer cautioned.

He suggests the rural sector should be considering plans to potentially move stock from low lying areas, and how they can later be fed.

He urges anyone with concerns to visit ORC’s Environment Data Portal on the front page of ORC’s website, for up-to-date tracking of river levels.

He says ORC staff are already activated and throughout the weekend will be monitoring streams, rivers and lake levels across Otago and updating relevant councils around any forecast flooding concerns.

MetService forecast

At about noon today, MetService reported a deepening low over the Tasman Sea was approaching the South Island on Saturday.

An associated front, preceded by strong northerlies and rain, is forecast to cross northern and central New Zealand.

Meanwhile, another front directs cool and moist easterlies over the South Island, with significant snowfall likely above 600 metres from Canterbury southwards.

Area: North Otago and Dunedin
Period: 15 hours from 9:00am Sat 26 Oct to 12:00am Sun 27 Oct
Forecast: Rain, heavy at times. Amounts may approach warning criteria. Moderate chance of upgrading to a Warning.

Area: Queenstown Lakes District
Period: 18 hours from 6:00am Sat 26 Oct to 12:00am Sun 27 Oct
Forecast: Periods of heavy rain, and amounts may approach warning criteria. Note, rain is likely to fall as heavy snow above 600 metres, and a Heavy Snow Warning is in place for the Queenstown Lakes District and Central Otago. Moderate chance of upgrading to a Warning.

Area: Fiordland
Period: 23 hours from 8:00am Sat 26 Oct to 7:00am Sun 27 Oct
Forecast: Southeast winds may approach severe gale in exposed places. Moderate chance of upgrading to a Warning.