Weather: Another 'big low' to bring thundery weather

Thunderstorms, squalls, heavy rain and snow are back on the radar this week as another "big low" heads towards New Zealand.

On Tuesday an active front moves east from the Tasman Sea, followed by a "complex and slow-moving low-pressure system" on Wednesday through to Friday.

"These weather systems are expected to bring rain to many parts of the country with the heaviest falls about the western regions of the South Island and the central and southern districts of the North Island," MetService says.

WeatherWatch says the low pressure system could drop as low as the late 960hPa (Hectopascal) range on Thursday.

"The lower the air pressure the more unstable the weather becomes over a larger area, meaning thunderstorms, squalls, heavy rain and snow are all possible. It also increases winds around the centre of the low," it warns.

MetService's latest severe weather outlook includes a moderate confidence of warning amounts of rain for many parts of New Zealand, including Westland, Fiordland, Waitomo, Taumarunui, Taupo, Taihape, northern Taranaki and the Tararua Range.

There is also a moderate confidence of severe gales affecting inland parts of Marlborough, the Canterbury High Country, the Otago Lakes, and also Westland and Fiordland.

Newshub.