Weather: Thunderstorm warning for West Coast, almost a million lightning strikes over Tasman Sea

Almost a million lightning strikes have been recorded over the Tasman Sea in a 24-hour period, and the thunderstorms are heading for parts of New Zealand.

MetService has issued an orange heavy rain warning and a severe thunderstorm watch for parts of the West Coast of the South Island, along with heavy rain watches for Nelson Lakes and Fiordland.

“It’s, unfortunately, looking like a very wet day,” MetService meteorologist John Law said.

A severe thunderstorm watch has been issued from Greymouth to Fiordland until 9am on Thursday, with 45mm of rain an hour possible at times and hail up to 20mm in diameter.

The National Institute of Water and Atmospheric Research (Niwa) said there had been “well over” 800,000 lightning strikes over the Tasman Sea in the 24 hours until 1pm on Wednesday.

The Tasman Sea has been electrifying!

Well over 8⃣0⃣0⃣,0⃣0⃣0⃣ lightning strikes have been observed in the past 24 hours.

Note the waves of thunderstorms (lightning) moving southeast.

Thunderstorms will become more widespread & active over much of NZ in the coming days. pic.twitter.com/Jvtb02cd5L

— NIWA Weather (@NiwaWeather) March 8, 2023

“The waves of thunderstorms [are] moving southeast,” Niwa said.

“Thunderstorms will become more widespread and active over much of NZ in the coming days.”

MetService’s Law said 38,000 lightning strikes hd already been recorded around New Zealand - most offshore, with 135 on land in the past 24 hours. should lapse at d6pm on Thursday.

MetService’s Law said 38,000 lightning strikes had already been recorded around New Zealand - most offshore, with 135 on land in the past 24 hours.

The electrical storms should ease throughout the day before picking up in the evening, he said.

Significant lightning in the Tasman with some moving towards Westland this afternoon. A Severe Thunderstorm Watch is in place for Westland along with a Heavy Rain Warning. Tomorrow will be thundery too, even for some other SI areas - check https://t.co/Yjbq0jgaoz for details. pic.twitter.com/Oom3CW79eA

— MetService (@MetService) March 8, 2023

Between 200-300mm of rain is forecast for the ranges between Otira and Bruce Bay.

Law said 32mm of rain was recorded to have fallen in an hour near Haast.

“This kind of rainfall could cause surface and flash flooding, hail can damage things like crops and vehicles,” Law said. “So it is worth keeping that in mind and keeping up to date with the latest forecasts.”

He said a “very active” front was moving up across from the Tasman Sea.

“There’s a lot of warm air at the surface and cooler air aloft, which is making for some pretty intense rainfall,” Law said.

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