The worst of the wet weather is over, with Christmas Day’s heavy thunderstorms expected to be the last of the year in Wairarapa.
Metservice lifted its severe thunderstorm warning for the region late on Sunday night, after a “vigorous” cloud burst inundated Carterton and parts of South Wairarapa.
A MetService forecaster said the country had experienced thousands of lightning strikes, with severe thunderstorm watches issued for Wairarapa, Hawke’s Bay, Bay of Plenty, and Gisborne.
Forecaster Sonja Farmer said 2200 strikes had been recorded, mainly in the eastern North Island ranges, inland from Hawke’s Bay.
Heavy rain between 5-7pm on Christmas night led to widespread surface flooding on Carterton’s High St and Papawai east of Greytown.
Metservice meteorologist Dan Corrigan said the thunderstorm warning related to two main “thunderstorm cells” which burst directly above the towns.
“There was one that was further inland toward Carterton where we saw that surface flooding and an equally vigorous one toward Papawai and the hills. “It developed over Greytown and drifted westwards.”
Corrigan said rain gauges in those areas that captured the thunderstorm recorded more than 20mm of rain in the space of an hour.
Gauge south of Greytown recorded 23.1mm of rain between 5-6pm, and another near Tauherenikau clocked 22mm between 6-7pm.
He said in the past week, Wairarapa had been a hotbed for thunderstorms, with all the right elements for tropical bursts present.
“We had high humidity, combined with daytime heating and other ingredients involved.
“When those things come into line, a thunderstorm will pop up, but it’s hard to know exactly where.”
Corrigan said thunderstorms were typically hyper-localised only covering a couple of square kilometres when the cloud burst.
“That’s why you can get surface flooding in Carterton but then out toward the coast or Lake Ferry, nothing.
“You might be under blue sky, and in the distance, you see a puffy white cloud where a thunderstorm is bubbling.
“It can be polar opposite. Depending on where people were in Wairarapa, they likely experienced very different weather on Christmas Day.”
He said there was good news on the horizon, however, for trampers and beach-goers with warm dry weather forecast for the next week.
Corrigan said the ingredients for thunderstorms were not forecast, and although there was the potential for an occasional shower it was unlikely.
“The atmosphere is more stable now. We might see some white puffy cumulus clouds on a summer afternoon, but they won’t get tall enough for a thunderstorm.”
He said a high-pressure system settling across most of New Zealand and was expected to last.
“We’re looking at some fine weather in the lead-up to New Year in Wairarapa.
“It’s also a nice time to go to the Tararuas. There isn’t a great deal of wind there at the moment. We’re looking at mostly fine weather.”
