There’s some classic spring weather on its way this week – the kind that brings gales and unpredictable bursts of rain.
But we’ve got one more day of relative calm before the storm, MetService forecaster Sonja Farmer says.
The upper half of the North Island can expect cloud and isolated showers on Monday, with fine weather elsewhere.
In the South Island, warnings are in place for Monday. It will start out cloudy in the west with showers turning to rain in the afternoon, with heavy rain and gale warnings in place.
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“The last few days we’ve had pretty stable and settled weather with that high out to the edge of the country but that’s going to change in the days forward,” Farmer said.
A complex low pressure system sitting over the Tasman Sea would move over the country in the next few days, hitting the southwest and west coasts of the South Island first.
Heavy rain would arrive on Monday and strong winds and heavy rain in many places on Tuesday.
It’s going to be messy thanks to a number of warm and cold fronts embedded in the weather system.
“They all have their effect on that weather…It might seem like it’s raining all day but in actual fact it might be one front going over, a little bit of a pause and another front going over.”
Rain or showers were expected almost everywhere, every day until Friday – though the east coasts of both islands could miss the worst of the weather, with more scattered rain, Farmer said.
“This sort of weather tends to fall before it hits the ranges, and then the people in the east coast of those areas get off a bit better.”
On Wednesday snow was possible down to 300m in the south.
There was good news for West Auckland – at this stage the sodden areas hit by last week’s storms are only in line for showers or light rain this week.
Farmer said it was too soon to make firm predictions about the weekend’s weather.
Overall Niwa is forecasting a relatively balmy spring, following on from New Zealand’s warmest-ever winter.
That could mean warmer-than-average stints, particularly on the east of both islands – although cold spells and frosts could still occur.
Forecaster WeatherWatch said a subtropical airflow was being dragged down on to southern and central New Zealand, bringing above average temperatures in some areas.
“In the days ahead developing low pressure and a cold front out of Australia are heading our way with rain from the west and a temperature drop coming nationwide.
“Showers and rain start to increase on the West Coast as of Sunday with heavy falls,” WeatherWatch said.
The forecaster predicted 100-150mm of rain was possible while lighter showers could be expected in the north.
Coastal parts of the upper North Island have seen easterly winds this week, and these would increase in the next two days before turning to stronger southwesterlies on Wednesday.
Heavy rain, gale warnings for the South Island
From tomorrow afternoon heavy rain is expected in Fiordland and Westland. “Significant amounts” could spill over into the headwaters of the Otago and Canterbury lakes and rivers, MetService’s website says.
Heavy rain in Westland and Fiordland in the afternoon and evening could cause streams and rivers to rise rapidly with surface flooding and slips possible. Between 90mm and 120mm is possible.
Severe northwest gales may affect exposed parts of the lower South Island and the Canterbury high country from Monday morning through to overnight.
Trees, powerlines and unsecured structures could be damaged by strong wind gusts, and driving could be hazardous.
A heavy rain watch is also in place for Canterbury and Otago tomorrow night.
Further watches and warnings could be added in the days ahead.
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