Thunderstorm threats for Hawke's Bay don't come to fruition

Clouds hovered over an abandoned building in Poukawa, south of Hastings yesterday afternoon. Photo / Paul Taylor

It was somewhat of an anti-climax for weather watchers in Hawke's Bay yesterday, as threats of a severe thunderstorms, proved just that - threats.

MetService issued a severe thunderstorm watch for much of the central and northern north Island from 12.29pm through to 9pm yesterday.

It said there was a moderate risk that some thunderstorms across the North Island could become severe, with localised downpours of 25 to 40mm/hr and large hail 20 to 25mm in diameter.

Hastings District Council urged residents to heed warnings through social media during the afternoon.

But despite that, it was mostly sunny throughout the day, with cloud and a few showers.

MetService Meteorologist Peter Little said there had been a few thunderstorms near Waipawa and inland of Wairoa, with one producing "fairly large hail" about 10mm in size.

There had also been 11mm of rain recorded for the hour from 4pm in Central Hawke's Bay.

Lat night, Little said as the heat was diminishing, the likelihood of any severe thunderstorms for the rest of the evening was minimal.

However, the region had 550 lightening strikes, mostly inland and about the ranges.

At this time of year thunderstorms and lightening strikes are particularly common, with increased heat from the sun, Little noted.

"One of the ingredients of thunderstorm development is having buoyancy, which means if you have a lot of heating at the surface and then you get cold air in the upper-atmosphere, that gives you instability because the warm air wants to rise.

"This time of year, you tend to still get quite cold air in the upper-atmosphere and you are starting to get increased heating at the surface, with the sun getting stronger."

Looking ahead to today, the risk of thunderstorms is low, with any possible thunderstorms to occur inland and during the evening.

"We have got a low pressure system, which is currently out to the northeast of Northland and that is going to push southwards and bring some rain to the east coast of the North Island."

As well as periods of rain, southerlies are expected and a high of 20C in Hastings.