Ensemble Forecasting

The wisdom of the crowd Wisdom of a crowd At a county fair in Plymouth, England, in 1906, several hundred fair-goers entered a contest to guess the weight of an ox. The average guess was extremely close to the true weight of the beast – even though some of the individual estimates were wildly off the mark!

A satellite image for every occasion

By Rebekah LaBar, MetService Meteorologist Satellites are one of a meteorologist’s best tools. Satellite images can tell us where weather systems are and how fast they are moving. They can also often help us distinguish between many things such as thick and thin clouds and high and low clouds, as well as detecting snow, fog, volcanic ash, smoke, thunderstorms, and much more.

Jack Frost to make an appearance

By Rebekah LaBar, MetService Meteorologist

The low-pressure system that brought cold weather, snow, and thunderstorms to New Zealand is pulling off to the east today. An unsettled southwest flow will continue to dominate the weather this week, although temperatures will gradually rise as we head towards the weekend and the recent snowfalls will start to melt.

Cold blast to start the week

A deep upper-level trough of low pressure is moving over the South Island of New Zealand today, while an associated surface low lies to the southeast. The trough is dragging up cold air all the way from Antarctica in our first significant cold outbreak of the year that will continue to bring snow to parts of the South Island and high elevations of the North Island today and tomorrow. Thunderstorms with small hail are also possible. As the low-pressure system strengthens, it will also bring strong winds and high swells to coastal areas of especially the South Island.

Snow to low levels over the South Island on Monday

A burst of cold air originating from the Antarctic ice sheet is expected to affect New Zealand on Monday and Tuesday. Unseasonably cold temperatures, strong winds and snow to low levels are expected over the South Island where this event is likely to have a high impact. Snow is forecast down to around 200 to 300 metres in Fiordland, Southland and Otago but 400 to 500 metres in Canterbury. Hail and snow flurries could penetrate even lower. People in places such as Invercargill and Dunedin may see some snowflakes that melt as they hit the ground.

Polar outbreak on Monday and Tuesday

A burst of cold air originating from the Antarctic ice sheet is expected to affect New Zealand on Monday and Tuesday. Unseasonably cold temperatures, strong winds and snow to low levels are expected over the South Island where this event is likely to have a high impact. Livestock could be affected and it will probably have an effect on higher roads where significant snow accumulations may make driving conditions difficult and could lead to some road closures.

Winter is coming (for a bit) - updated Friday 10 April 2015

Update by Peter Little, MetService Meteorologist, at 4.30pm

A polar blast due early next week will see temperatures plummet in many places, with snow expected to unseasonably low levels over the South Island and lower North Island. On Monday, MetService is expecting snow to fall to 400 metres in the far south of the South Island and to 600 metres on Banks Peninsula. Early Tuesday, snow is expected to lower to 900 metres for a time on the Tararua Range.