Autumn is going out with a blast next week as a series of storms swipe parts of New Zealand & Australia.

On the meteorological calendar Autumn finishes Tuesday May 31 and winter starts Wednesday June 1st. The weather pattern next week looks stormy, initially across Australia’s southern states then it crosses the Tasman Sea and into New Zealand.

“We have Southern Ocean southerlies this week but by Sunday afternoon parts of New Zealand will momentarily have subtropical airflows from Tahiti, Tonga and Fiji” says WeatherWatch.co.nz head forecaster Philip Duncan. “This means a big jump in overnight temperatures from where we are this week”.

For example:

• Gore: -2C tonight, +8C by Monday
• Christchurch: +2C tonight, +12C by Monday
• Hamilton: +2C Thursday night, +14C by Sunday night

The subtropical nor’east flow around Sunday and into Monday will bring some rain, then it’s followed by a nor’west change – which will still be mild – and will be fuelled by low pressure in the southern Tasman Sea.

This low pressure could drop to the 960hPa range as it joins up with storms in the Southern Ocean, creating a very large low pressure zone that drives in snow to the ranges of south eastern Australia, severe nor’west gales in New Zealand and heavy rain for the South Island’s West Coast (maybe the North Island’s west too).

One week from now, Wednesday June 1, low pressure may well then be crossing NZ, then followed by a brief wintry southerly change.

“As we said in our last ClimateWatch update, there were hints of a more normal weather pattern coming into the NZ area for June and some of the modelling suggests we’ll be seeing more westerly driven rain bands and lows than perhaps the recent months have had” says Duncan. “La Nina continues to fade and in our part of the world that may well allow the more usual westerly driven weather to kick back in again”.

WeatherWatch.co.nz says reliable long range data sees a healthier mixture of high and low pressure zones coming in from the west over the coming two weeks. Our next ClimateWatch update for June and Winter will be out next week on May 31 covering the likely rain and temperature trends for the month(s) ahead.

Our weekday videos are now also focusing on this stormy pattern next week.

WeatherWatch.co.nz – NZ’s weather news authority.