Torrential rain and thunderstorm warnings are in place as a low-pressure centre passes over the country.

MetService public meteorologist Alwyn Bakker said a low-pressure centre that was being tracked was expected to cross over the lower North Island and upper South Island tomorrow.

“Which may have some heavy rain associated with it, and if required we will issue heavy rain watches or warnings for that situation.”

Today several severe thunderstorm warnings were issued for regions around the country.

In the North, Waikato, Waitomo, Taumarunui, Bay of Plenty, Rotorua, Taupo, Gisborne, Hawke’s Bay, Taranaki, Taihape, Wanganui, Manawatu, Tararua, Kapiti-Horowhenua, and Wairarapa were expected to encounter seven hours of heavy rain from 2-9pm.

And in the South, Central Otago, Southern Lakes, Dunedin, Clutha, Southland, and Fiordland were expected to be hit with nine hours of rain from 1pm-10pm.

“Thunderstorms are expected to develop around midday, and some of these may become severe from early afternoon until this evening, bringing localised downpours with intensities of 25 to 40 mm per hour,” MetService said.

 “There is also a low chance of a small tornado forming. The thunderstorms are expected to ease this evening.”

Rainfall of this intensity could cause surface or flash flooding, especially in low-lying areas such as streams, rivers or narrow valleys, and might also lead to slips, the national weather authority said.

“Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain.”

The forecast would improve leading up to Christmas, Bakker said.

“Today would generally be showery or drizzly with some thunderstorms in the mix, but South Island would get the better deal, with the east coast from Canterbury southwards getting plenty of fine breaks, and most of the shower activity elsewhere holding off until this afternoon.

“Friday (tomorrow) will be generally fine, apart from scattered showers through inland areas in the afternoon or evening, and possibly thunderstorms associated with those showers.

“Also, a low-pressure centre may trigger showers through the lower North Island and upper South Island during the day.”

The weather over the Christmas weekend looked generally good, he said.

“At this stage, the weather is looking generally good for the Christmas weekend. On Saturday (Christmas Eve) we’re expecting a few showers for the West Coast, and generally fine weather elsewhere, apart from scattered afternoon and evening showers inland.

“Sunday (Christmas Day) is looking even better, as those showers for the West Coast are expected to clear out early in the morning, and inland places will see only the odd shower in the afternoon or evening.

“Aside from some inland showers and possible thunderstorms, it’s all looking pretty good.”

Bakker said holidaymakers should still be prepared for any possible severe weather events as they hit the roads.

In the west from Northland to Kapiti, including the Coromandel Peninsula, Bay of Plenty and the central high country the weather looked wet, with scattered showers, some heavy, thunderstorms and hail possible from the afternoon.

In Gisborne and Hawke’s Bay clouds and patchy drizzle were breaking up this morning, but then fine breaks and a few showers. Some heavy rain with thunderstorms and hail was possible.

Wairarapa, Wellington, and Marlborough looked cloudy with a few showers.

Nelson and Buller would experience cloudy periods.

“Showers retreating inland this afternoon, with a chance of thunderstorms and hail,” the MetService forecast said.

Westland and Fiordland were mostly fine. Showers are to be expected from late morning, mainly about the ranges, some heavy with thunderstorms and hail possible.

Canterbury, Otago and Southland are partly cloudy. Showers are expected to be developing late morning, mainly inland, where some could be heavy, with thunderstorms and hail possible.

In Chatham Islands, light rain was becoming heavier this evening.