Up to 400mm of rain will drench parts of New Zealand over the next three days as a slow-moving front drifts northwards across the country, MetService reported.
The severe weather threatens western regions of the South Island and central New Zealand with torrential downpours and severe gales. Orange heavy rain warnings and strong wind watches cover multiple districts from Sunday through Tuesday.
Streams and rivers may rise rapidly while surface flooding and slips disrupt transport networks. Roading crews are on standby to clear debris from highways.
“Heavy rain means slippery roads and drivers should think about adjusting their speed and travelling distances, avoiding sudden braking, and staying visible,” the New Zealand Transport Agency said.
The Westland ranges and Canterbury main divide face the heaviest downpours, with 300 to 400mm of rain expected. Peak rates will reach 30 to 40mm per hour on Monday morning, Radio New Zealand reported.
An orange heavy rain warning for the Westland District runs from midday Sunday until 1pm Monday. A separate warning for the headwaters of the Canterbury lakes and rivers south of Arthur’s Pass runs from 2pm Sunday until 2pm Monday.
Further north, the ranges of the Grey District expect 100 to 130mm of rain between 10pm Sunday and 2pm Monday. The Buller District ranges face 90 to 130mm of rain from 3am to 5pm on Monday, with peak rates of 20 to 30mm per hour.
The stormy front extends to central New Zealand and the North Island, bringing severe northwest gales and heavy rain. The Tararua Range north of Wellington is under an orange heavy rain warning from 3pm Monday until 4am Tuesday, Stuff reported.
Meteorologists expect 100 to 150mm of rain to accumulate in the Tararua Range. Strong wind watches are active for Wellington and Wairarapa south of Masterton from midday until 8pm Monday.
The Canterbury High Country also faces a strong wind watch from 10pm Sunday until 10am Monday. Northwest winds may approach severe gale force in exposed locations.
Transport authorities advise motorists to exercise extreme caution across affected state highways. Drivers should avoid floodwaters of unclear depth and watch for hidden obstacles.
“People should also avoid travelling through floodwaters where the depth is unclear or there may be hidden obstructions,” the New Zealand Transport Agency said.
Operators of motorcycles, towed vehicles, and high-sided vehicles like campervans should take extra care in high winds. MetService noted a moderate chance that current wind watches will be upgraded to full warnings.
The orange heavy rain warning for the Westland District ends at 1pm on Monday, according to MetService.
Peak rainfall rates of 30 to 40mm per hour are expected about the Westland ranges and Canterbury main divide on Monday morning.
The New Zealand Transport Agency deploys roading crews to respond to flooding, slips, and debris blocking state highways.