A high pressure system sitting over New Zealand is keeping the large storm battering New South Wales at bay - but is only days away from hitting New Zealand.
The storm - billed a 'once in a decade' event - has entered day three, with three dead and two missing. It continues to lash Australia's east coast with 100km/h winds and heavy rain, leaving more than 200,000 without power.
"The high pressure system over New Zealand is acting like an invisible wall out over the Tasman Sea, holding this low in place near Sydney and bringing day after day of torrential downpours, huge seas and damaging winds," head weather analyst at WeatherWatch Philip Duncan said.
Fog and smog over parts of New Zealand today was caused by the calm conditions under the high.
However, the high over New Zealand is already starting to move further east - and like gridlocked traffic the low near eastern Australia will start to follow slowly behind it, Mr Duncan said.
"By Friday the low just off Sydney's coastline will weaken significantly - as mostly dry weather remains over New Zealand; however, with the high drifting further away to our east a northerly quarter wind flow will develop over the country."
This means a warm weekend for many, with winds from the northwest to northeast for many regions. But by Sunday the leftovers of the Australian storm will be reforming over the southern Tasman Sea and begin to loom over New Zealand..
A new, larger low will deepen rapidly on Sunday evening and into Monday morning as it starts to cross New Zealand.
"Some parts of New Zealand will have a wet and windy public holiday on Monday - with the low affecting most of the country at some point across the day," Mr Duncan said.
"Like New South Wales the low will take a few days to clear New Zealand - however, it will be a different low by the time it reaches New Zealand with any potential severe weather coming in different forms."
There is a chance of isolated thunderstorms across Monday and Tuesday. Heavy rain is also possible in western areas, he said, with strong to gale-force winds in some areas.
"A repeat of the major damage in parts of New South Wales is not expected in New Zealand. However, the low will have enough energy to create localised damaging weather in some parts of our country."
- Patrice Dougan of NZME. News Service
