MetService’s five-day rain forecast imagery shows a mass of rain from the Tasman Sea slamming into Fiordland early this morning and fully enveloping the country early tomorrow.
MetService meteorologist Lewis Ferris said it was “a bad start for the first week of the school holidays”.
A 24-hour orange heavy rain warning came into effect for the Westland District at 11pm last night. Meanwhile, warnings will also come into force for Tasman northwest of Motueka, Richmond and Bryant ranges including the Rai Valley, and Mount Taranaki throughout Wednesday.
Up to 190mm of rain is expected on the West Coast, threatening to cause streams and rivers to rise rapidly, surface flooding, slips and difficult driving conditions. MetService urged people to clear drains and gutters in preparation.
A swathe of heavy rain watches have also been issued from Northland down to Bay of Plenty, with moderate-to-high chances they would be upgraded to warnings.
Ferris said the potentially severe weather is brought about by a low-pressure system approaching from the Tasman Sea, which drags some warm and humid air across New Zealand’s shores.
“While this does mean some warmer than average temperatures it also increases the chance of heavy rain as the system passes over.”
Road snowfall warnings are in place from 9am today at the earliest for Crown Range Rd, Milord Rd (State Highway 94), Lindis Pass (SH8) and Haast Pass (SH6). These should all lapse by 3am Thursday.
Snow is possible down to 500m in Otago and South Canterbury on Thursday, when a mass of cold air passes over the South Island.
Ferris said: “On Thursday, as a low-pressure system gets close to our shores, it drags in some cold air from the south of the South Island, and that’s lining up with the band of rain that brings the risk of snow.”
It comes as Niwa warns of a potential for more downpours throughout October, amid an emerging “La Nina-like” pressure pattern raising the odds of big rain events.
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