The storm that hit the lower North Island and caused extensive damage to farmland was not given a red warning status by forecasters. Blue Skies Weather forecaster Tony Trewinnard says the event was forecast, but the extreme rainfall that fell was not.

“I don’t want to suggest there’s a problem with the weather warning system in New Zealand, but I think it could be refined to become more useful,” he says.

MetService cannot institute a red warning on its own, needing to involve Civil Defence, NEMA or local authorities in a collaborative decision to lift an orange warning to red.

“I just wonder if that structure is really optimal for some of these weather events that we’ve been experiencing in the last year or two, and whether in fact people fully understand it and get on board with it.”

He says warmer-than-normal ocean temperatures around New Zealand are behind the quirks in the weather, not El Niño.

“El Niño is still building up in the tropical Pacific; it hasn’t really coupled up to drive weather patterns at the moment.”

He says the current pattern is the legacy of the La Niña that dominated the past two years. Sea surface temperatures sit about one to two degrees warmer than normal for the time of year, stretching across the Tasman Sea into the Southern Ocean.

“That’s why you’re seeing these low-pressure systems filled with moisture and warmer air in the North Island when they come along, dumping heavier rainfall than you might otherwise expect.”

This week stays settled under a high crossing the South Island, before the pattern breaks down at the weekend.

“Next week sees quite an unusually active series of weather systems forecast to move over and around New Zealand.”

Trewinnard forecasts cold outbreaks, snow on the mountains and possibly the Canterbury Plains, and gales through Cook Strait.

“We may yet see another significant rainfall along the east coast of the North Island, particularly the Wairarapa Coast, again.

“It might not happen, it’s not in the forecast, but it’s within the range of possibilities for an active weather week next week.”

The El Niño signal keeps building, but he says its strength is a poor guide to how dry the east of the South Island will get.

“We tend to get drought regardless of whether or not there’s a strong El Niño.”

CountryWide CONNECT with Andy Thompson & Sarah Perriam-Lampp is our daily rural show livestreamed from 11am-1pm. Visit country-wide.co.nz on how to watch/listen or download the CountryWide CONNECT mobile app, available on Apple iOS and Android.