Rain has been falling steadily throughout the Clutha District and combining with snowmelt at lower elevations, resulting in widespread surface flooding on some parts of the roading network.
In West Otago, Pomahaka Road is now closed from SH90 to Dickison Road with a detour up Dickison Road and down Dalvey Road, which is now open.
Flooding signs are up on Black Gully West Road.
Extreme caution is advised for roads in West Otago especially on Dalvey Road where water levels may rise again overnight.
The Pomahaka River level is rising and will be monitored overnight.
Near Milton, flooding signs are up on Springfield Road and Back Road. Mud tanks in Milton, Balclutha and Kaitangata have all been inspected and cleared where required.
Heavy snow was forecast to hit inland Otago and Southland today and Dunedin residents should prepare for freezing temperatures and snow from tomorrow, the MetService says.
MetService meteorologist Lisa Murray said a heavy snow warning had been issued for inland parts of Southland, Otago and South Canterbury, south of Fairlie, with between 20cm and 30cm of snow expected above 400 metres today. Ranfurly's elevation is 430m.
"We are giving people a heads up because it could be quite significant, especially for people in inland areas - they could get caught out and be stranded for a few days, so we are trying to get people to be prepared and get their supplies in.''
In the Clutha district, rain was expected to turn to snow above 200 metres, the local council advised. In the 12 hours from 8am today, expect 15cm to 25cm to accumulate above 400m, with 5cm to 10cm possible down to 200m. Blizzard conditions were likely in exposed areas, it said.
Contracting teams were busy on many local roads and state highways on snow ploughs and gritting trucks, the New Zealand Transport Agency advised. Journey manager Lee Wright said people should drive to the conditions, as more snow is forecast in places including alpine roads the Lindis Pass, Lewis Pass and Porters Pass.
“Please check the MetService for updates. Those travelling through alpine passes or travelling in the south of the South Island and inland areas should carry chains regardless and know how to put them on. Chains are for the driver’s and road users’ safety, so please ensure you have them and know how to put them on. Allow extra time.”
Dunedin set to shiver
A complex low-pressure system was expected to move on to the country from the South Tasman Sea today then move northeastwards across New Zealand tomorrow and Friday, bringing rain to many parts of the country and snow to low levels in the South Island's east.
A cold air mass was expected to hit Dunedin tomorrow, pushing temperatures down to freezing and heralding two days of snowfalls.
A blanket of snow would cover the hills surrounding the city, and snow could settle in central Dunedin. A "snow day'' for Dunedin residents was more likely on Friday than tomorrow, she said.
When the cold air mass arrived, the temperature in central Dunedin was forecast to fall to zero overnight and at Dunedin Airport could plummet to -5degC before dawn.
The maximum temperature in central Dunedin on Saturday would be 5degC. "It's going to be coooooold ... so wear your hat, gloves and scarf - the whole shebang,'' Ms Murray said.
Roads and transport
The Milford Road (SH94 Te Anau to Milford Sound) is closed from Hollyford, NZTA said. The Danseys Pass Road is also shut.
There is snow and ice between Kawarau Falls, near Queenstown, Otago and Lumsden in Southland (SH6).
Caution is needed when travelling from Dunedin to Waitati (SH1), Fairlie to Twizel (SH8) and the highway to Aoraki/ Mt Cook (SH80). Snow will also affect all alpine passes throughout today and overnight.
• Check major road conditions on the NZTA website
Chains are essential on the Crown Range Road linking Queenstown and Wanaka. All other roads are open and people should drive to winter conditions as widespread snow is forecast today, the Queenstown Lakes District Council said.
Motorists are being warned of flooding on State Highway 1 at Morven, near Waimate and should drive to the conditions.
Queenstown Airport said there could be flight disruptions due to conditions today. Passengers should check online at queenstownairport.co.nz for updates.
Avalanche warning
An avalanche risk warning has been issued for the next 48 to 72 hours across the country, the New Zealand Avalanche Advisory stated.
The areas of high risk include Mount Cook and Nelson Lakes.
Tongariro and Taranaki also had warnings issued.
"Our forecasters are predicting some lower altitude regions to have an avalanche risk in the next 48 -- 72 hours which is pretty uncommon.
"Places that normally may never have a risk are now potentially vulnerable to slab avalanches," New Zealand Avalanche Advisory forecaster Trevor Streat.
He said it was likely a cycle of "loose wet snow avalanches" at lower elevations when the temperature rises.
"This could affect roads and tracks traversing steep terrain or cutting beneath bluffs that don't usually have a problem. People need to consider how much snow is sitting on the slopes above before moving out on the first day that things warm up," he said.
He said this could affect roads and tracks in places where drivers would not expect avalanches.
Slab avalanches were more likely in high snowfall that occurred in steep terrain and over a short period, he said.
"Storm Slab avalanches are typified by heavy loading in a storm. Once this is warmed up as the storm passes, it can become very unstable. This could include traditional farming regions of the South Island that are potentially due to get loaded from a south to south-east weather flow in the coming days."
The Mountain Safety Council advised backcountry skiers, snowboarders, climbers and trampers the next week could be a very dangerous time to explore the backcountry in certain parts of the country.
"We know it's an exciting time, and the snow is finally here, just make sure you're making good decisions. It's about having a great time and making it home to your family."
- additional reporting Shawn McAvinue
