Snow has closed roads in parts of the South and some roads in Dunedin have been flooded in heavy rain, as wild weather hitting much of the country moves into Otago.
MetService has issued an Orange Alert covering Dunedin, with between 70 and 100 millimetres of rain forecast from 1pm on Tuesday until 10am on Wednesday. Snow was also expected above 300 metres.
The Dunedin City Council urged residents to take care as it prepared for heavy rain and snow to arrive from this afternoon.
The council said contractors have been checking the city's stormwater and wastewater systems, sweeping gutters and checking mud tanks in low-lying and high risk areas. Residents who notice a blocked mud tank near their home are asked to clear debris on to the foot path.
The council warned that "significant rain could cause flooding and slips and make driving difficult".
By 8.30pm today, it advised that four roads had been closed due to flooding: Flagstaff/Whare Flat Rd; Gladfield Rd - Silverstream ford; Waitati Valley Rd - Ford north of Donald Rd and Miller Rd; Miller Rd, Waitati - closed at Waitati River ford.
The Otago Regional Council said this afternoon it was closely monitoring the deteriorating weather system around the region, and it was likely there would be some low-lying flooding of farmland in North Otago catchments, including the Kakanui River.
The Gordon Rd spillway along the Silver Stream near Mosgiel may be triggered into action.
If there was any escalation in the weather tonight, further notices and contact with residents would be made by Emergency Management Otago, with some residents in the Gordon Rd floodway area having already been contacted as a precaution earlier today. (The Gordon Rd spillway is a lower section of the Silver Stream floodbank located on the true right bank between Gordon Rd and Riccarton Rd opposite the urban part of Mosgiel.)
In Dunedin, there was not expected to be any overtopping of the Lindsay Creek channel in North East Valley or of the Water of Leith channel.
A heavy rain watch also applied to coastal Clutha. That came on top of the forecaster yesterday issuing road snowfall warnings in Otago, including for Dunedin's Northern Motorway (State Highway 1) for tonight. That warning has now been lifted but sleet was still expected.
Snow disrupting travel
A heavy snow watch was in place for parts of North Otago, Central Otago and Queenstown Lakes. Fifteen to 25cm of snow might accumulate on parts of the Crown Range Rd between Queenstown and Wanaka, and on the Lindis Pass (State Highway 8) to the north, and lesser amounts could accumulate down to about 400m.
Snow has been causing disruptions on southern roads today and several major state highways are shut.
A spokeswoman for Waka Kotahi/NZ Transport Agency advised that heavy rain, snow and gale-force winds continue to keep key routes closed across the South Island late this afternoon heading into the night.
Contractors were working hard to clear debris and traffic management will be in place in some areas. Drivers should factor this into their travel plans and be prepared for delays.
Even where roads are open, road users should be alert to the dangers of surface water, rising river levels, rockfalls, fallen trees, and slips, Tresca Forrester, Journey Manager Waka Kotahi, said.
“Some roads will have debris over them and flooding which makes them particularly unsafe overnight."
A police spokeswoman said two cars had become stuck in a ditch on Crown Range Rd about 12.40pm, despite the road being closed. A grader helped pull them out.
Lindis Pass (SH8 from Tarras to Omarama) has closed due to heavy snow.
Danseys Pass Rd closed about 9.30am due to snow.
State Highway 8 between Fairlie and Lake Tekapo is closed due to snow and ice. There is no detour available so Waka Kotahi/ NZ Transport Agencty has advised people to delay their trips.
Aoraki Mount Cook Highway (SH80) has now also closed due to snow, with no detour available.
Four cars are believed to be stuck on SH80 due to the heavy snow on the road while a snow plough works to try and free them.
Haast Pass (SH6) was closed overnight, but reopened this morning.
On the Milford Road (SH94), rain may turn to snow near Homer Tunnel from 2pm until 9pm today. About 1 cm of snow was likely to accumulate on the road.
Caution is advised in the St Bathans area, as snow is settling on roads, and in Alexandra, Manuherikia and Earnscleugh due to reports of black ice with the rain and sleet freezing to roads.
Crews in trucks were out ploughing and gritting roads, the Central Otago District Council said.
The Waitaki District Council advised motorists to avoid unnecessary travel and to take due care.
Meanwhile, strong winds on the West Coast have brought down power lines, closing SH6 at Whataroa, and there are closures on other stretches of the highway as well.
MetService forecaster Aidan Pyselman said he expected the worst of the weather to bear down from about lunchtime today and this could extend into tomorrow.
The severe weather outlook was for a deep low and associated fronts, which have been bringing severe weather to much of New Zealand, to move away to the east of the South Island tomorrow.
ORC keeping eye on rising rivers and streams
Rain is expected to fall as snow down to about 500m in parts of North Otago, Central Otago and the Queenstown Lakes today.
The Otago Regional Council said it was keeping an eye on the rivers and streams in the region, as it was likely there would be low-lying flooding of farmland in North Otago catchments including the Kakanui River.
The Gordon Road spillway along the Silver Stream near Mosgiel may be triggered into action.
Duty flood officer Eve Bruhns said MetService has raised its prediction of rainfall in North Otago from yesterday, with the heavy rain warning from 1pm today for the following 21 hours expected to accumulate between 60mm-90mm of rain; with intensities up to about 15mm per hour.
“There’s still a lot of uncertainty around the extent of rain being expected."
The ORC’s Engineering Operations team were on the ground monitoring various ORC flood protection, drainage schemes and rivers, with no immediate concerns having been reported.
Ms Bruhns said a close watch was also being kept for coastal surges during high tides - at Dunedin's Port Chalmers about 2pm today and 2.30am tomorrow morning - saying any tide surges are unlikely, but could still be a “possibility” at this stage.
Given the snow and heavy rainfall warnings for several parts of Otago, travellers should be considering whether or not to venture out on roads and to check the Waka Kotahi/NZTA website for roading updates, she said.
For North Otago, and other parts of Otago, MetService now advised that the rain was expected to fall as snow above 300 metres - lower than predictions yesterday - and heavy snow above 500 metres in some places.
Peak flows on the Clutha River at Balclutha were not expected to go beyond 2000 cumecs.
The expected peak flow was significantly less than the peak observed in the February 2020 flood event.
“Flooding of low-lying areas adjacent to the river is likely but flows are expected to be well contained within the Lower Clutha Flood Protection and Drainage Scheme Floodbanks,” Ms Bruhns said.
The ORC’s drainage networks in West and East Taieri and Tokomairiro will likely be flowing “quite full”.
“Specific attention will be given by the ORC’s Flood Response Team to these areas and catchments as the predicted low could stall east of the South Island, resulting in further heavy rain."
MetService predicted the low should move away to the east of the lower South Island by Wednesday. Rivers and lakes in Otago’s headwaters were not expected to rise, she said.
Avalanche warnings
People are also being urged to reconsider heading into avalanche terrain until weather conditions improve.
The Avalanche Advisory has issued its second highest danger rating for Mt Hutt and Two Thumbs.
Warnings for dangerous avalanche conditions are in place for Tongariro, Taranaki, Arthur's Pass, Craigieburn Range, Aoraki/Mt Cook, Ohau, Nelson Lakes, and Aspiring National Park.
The advisory has issued moderate avalanche alerts for Queenstown, Fiordland, and Wanaka, but says the danger may increase if snow falls are heavier than forecast.
- additional reporting ODT Online
