Hawke's Bay's heavy rain warning still in place, 3 rural roads closed in Wairoa

Hawke's Bay's rain radar. Image / MetService

Northern Hawke's Bay was late on Wednesday hoping to escape the worst of a storm that had hit hard in Bay of Plenty and Gisborne-East Coast.

According to MetService and Hawke's Bay Regional Council figures, rainfall of 30-55mm had been recorded during the day to 5pm in most Hawke's Bay areas from Napier north, and with up to 100mm forecast overnight for Mahia and almost 70mm for Wairoa.

At Hawke's Bay Airport, just north of Napier, there had been 36.8mm of rain by 5pm, and 48mm at Te Haroto, on State Highway 5 between Napier and Taupo.

Wairoa Mayor Craig Little said no extraordinary issues had been reported in the area, but staff were monitoring river levels and related issues during the night as the storm reminded some of Cyclone Bola 34 years ago.

But it was more because of the similar path rather than the force, with Bola, on March 6-8, 1988, having brought three-day rainfalls in some places averaging more than 200mm a day and most notably demolishing the bridge over the Wairoa River in the centre of the town, as well as causing possibly the worst erosion ever seen on the hills of the region.

Little didn't expect anything of the same, reflecting much of Bola's erosion damage followed the opening of cracks in the hillsides during dry months previously.

This year had seen rain regularly month-by-month, and the town now has generators to operate essential services if power supply was lost.

Unison Networks customer relations manager Danny Gough said there had "surprisingly" been no supply issues in Hawke's Bay during the day, but added: "It's fingers-crossed stuff really."

Three rural roads have been closed by flooding or slips in Wairoa, as Hawke's Bay's heavy rain warning remained in place from 10am today to noon on Thursday.

Surface flooding in Marewa in February. Surface flooding is possible today and tomorrow. Photo / Warren Buckland

MetService was forecasting more heavy rain was likely from Thursday afternoon to Friday and the warning could be extended, especially about the Wairoa District.

Hawke's Bay Civil Defence Emergency Management Group (HB CDEM) reported it was also monitoring and preparing for potential impacts.

Group controller Ian Macdonald said HB CDEM had moved to a "monitoring" mode of operation on Wednesday morning due to the uncertainty of the weather situation.

"We're urging residents in Hawke's Bay to be prepared for heavy rain. We have spoken to MetService and their advice is that the situation is complex with a great deal of uncertainty, but heavy rain in Hawke's Bay is possible, with the potential for continued rain and swells into the weekend.

"Based on the latest advice from Hawke's Bay Regional Council engineers, using current rainfall forecasts and modelling, we are expecting around an annual (one-in-one year) weather event from areas in Napier to Wairoa."

He said all of major rivers were in good condition with river mouths open, and all councils in the region had put Business Continuity Planning measures in place, including checking and preparing stormwater systems and drainage pumps, and informing vulnerable communities.