A Tasman Low is beginning to thrash New Zealand, leading to heavy rain, squally thunderstorms and dangerous surf. A severe thunderstorm watch is current for the area from just north of Hawera extending to Hahei, including inland areas of Hamilton. Thunderstorms bring the risk of gusts reaching 130 km/h. As the low nears the North Island, winds are forecast to freshen throughout today and into the tomorrow morning. Tomorrow, severe gales will be felt around Auckland and upper parts of the North Island. In the south, Dunedin and Invercargill should also feel gusty, with gales likely. Heavy rain is forecast around Nelson, with falls in excess of 130mm. In the North Island around the Bay of Plenty, falls of 120mm is expected. Thursday morning should also feel windy, but winds will begin to slightly ease throughout the day. Heavy rain look to become more prominent around the eastern end of the Bay of Plenty and the eastern half of the South Island. Wellington and Christchurch will be amongst those feeling the strongest winds, but they should mostly ease across the nation by the evening. These cold southerlies will bring snow down to 400m around Otago, with heavier snowfalls expected for locations above 500m. This system started off the east coast of Australia as a weak low. Once it developed, the low was quickly directed eastwards by a strong upper jet. Conditions look to settle on Friday, but another strong cold front is due in the late weekend.