North Island hit by heavy rain, gales, tumbling temperatures; snow risk for many passes

Tuesday, 24 September 2019

Winter will return to the south of the country, with a Heavy Snow Watch in place in Fiordland.

Heavy rain is falling in many areas of the North Island as the arrival of southwest gales sent temperatures tumbling, and snow is expected in the south from Wednesday.

The chilly snap comes just after the spring equinox on Monday. 'It certainly is springtime but these aren't too unusual conditions for spring. It's a very changeable time of year,' Metservice meteorologist Lewis Ferris said.

That said, it wasn't something that happened every year around this time. A colleague had suggested similar cold snaps around the time of the equinox maybe happened once every five years.

In Auckland, the winds changed from strong northwesterlies to strong southwesterlies mid-afternoon on Tuesday.

It's been a wet and windy day for much of the North Island. The worst of that weather was expected to be over by late Tuesday afternoon, but a chilly snap is headed for the South Island on Wednesday.

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The temperature dropped from 16 degrees Celsius at 1.30pm to 11C by 3pm, while at Auckland Airport a gust of 81kmh was recorded, 'which is quite strong for them in the southwest winds', Ferris said.

At Whangaparaoa a southwest gust of 111kmh was recorded, while at Cape Reinga there was a northwest gust of 104kmh, ahead of the southwest change.

Heavy snow around eastern Southland, near Gore, in August. We maybe past the spring equinox but snow showers are forecast for the area on Wednesday evening.

In Napier the temperature dropped from 18C at 3pm to 11C at 4pm. 'The wind changed from a northwesterly, which has a warming effect for them, to a southerly,' Ferris said.

Strong winds were expected to continue into the evening but the strongest gusts were likely to have been over by 4pm. 'There was a real squeeze between the first front and into the next one.'

At a Tararua Range weather station in the Wellington Region 141.8mm of rain was recorded in the 24 hours to 4pm Tuesday. In the Auckland and Waikato regions, some stations had between 40mm and 50mm of rain in 12 hours, and one station in the eastern hills of Bay of Plenty had 88mm in 12 hours.

The heaviest rain was likely to be over by late afternoon. 'We have another feature working over the North Island at the moment,' Ferris said about 4pm.

'It looks like behind the front is the southwesterly, so it moves more to a showery regime. Western areas continue to see showers into the evening period as that front moves off to the east of the North Island.'

In showery conditions rain could still be heavy but would be more localised than earlier in the day.

'Because we have now moved into this southwesterly it's a colder air mass, and we have another cold air mass behind that which works its way up the South Island tomorrow, which lowers the snow levels.' Ferris said.

MetService is forecasting snow down to 100m in Southland on Wednesday, with periods of heavy snow expected in Fiordland.

Some snow could also fall in most of the alpine passes. That includes the Desert Road overnight Tuesday and overnight Wednesday, and the Napier-Taupō Road overnight Wednesday.

Snow could fall on the Milford Road overnight Tuesday and on Wednesday, and on many of the other South Island passes on Wednesday. Snow could get down to 200m on the Milford Road, 400m on the Crown Range Road, 400m on the Lindis Pass, 400m on Haast Pass, 600m on Porters Pass and 600m on Arthur's Pass and the Lewis Pass.

Snow showers are forecast for Gore from Wednesday evening, while Queenstown and Wanaka are expected to have snow on Wednesday afternoon.

Christchurch is forecast to have a wet Wednesday afternoon and evening, with the temperature dropping to below 10C after lunch as a southerly arrives. The temperature could drop to -1C overnight Wednesday.