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A blast of freezing Antarctic air is on the way, turning rain into snow in the South Island tonight, and turning its attention to the North Island from tomorrow.
Heavy rain, snow, gales, thunder and hail - not exactly a forecast many New Zealanders want to hear as
a large area of low pressure shifts onto the country.
The Waikato River is also precariously close to flooding over its banks and on to surrounding roads.
Western and central areas will be most exposed to the severe weather with the main front is now moving up the West Coast.
TRN's head weather analyst Philip Duncan says it may be a restless night for some. "Heavy showers, some with hail, coupled with thunder and winds up to gale force may wake a few of us up overnight tonight".
Mr Duncan says the weather sounds bad but probably won't cause too much damage. "This storm covers a huge area which is a good thing - it's spreading the energy over a much greater space which decreases it's intensity".
Most exposed to the wintry blast will be coastal areas along the nation's west coast.
"These downpours and thunderstorms will come right off the sea pushed along by a gale force westerly in some places. Surface flooding is a possibility in these places overnight and tomorrow".
Already today the Weather Watch Centre's lightning radar has picked up over 5200 lightning strikes, mostly out in the Tasman where the nastiest part of the storm still lies.
"Friday looks like it will be pretty rough for western and northern regions with a number of small fronts zipping by". Mr Duncan says conditions aren't expected to clear until mid way through next week.
Despite the nasty weather predictions many regions hit by flooding last month aren't likely to see a repeat. "This system is moving in from the opposite direction, so a number areas vulnerable last time, will be sheltered this time around.
Mr Duncan says Waikato is probably the most recently flooded region still exposed to heavy rain from this system. "This storm is very different in its set up to July's one as it's moving in from the south west and not from the moist sub-tropics.
However heavy falls are possible which means isolated pockets of surface or flash flooding are possible - and of course the bigger concern will be how much rain falls in the upper Waikato River catchments, around Taupo. There may be some delayed flooding as the storm surge moves down the Waikato river in a few days time".
He says concerned locals along the river should stay up to date with MetService weather warnings and Environment Waikato.
The Waikato River is continuing to rise but is not expected to threaten homes in Hamilton, Civil Defence told NZPA today.
The river is expected to rise to 16m in the city as a result of the controlled release of water from Lake Karapiro, in turn releasing pressure on Lake Taupo which is at capacity, Waikato Civil Defence spokesman Paul Blewman said.
Heavy rainfall forecast for Taupo tomorrow is expected to put further pressure on the river system.
"The increased levels may bring the river level closer to residents' land in the lower areas of Ann St and Awatere Ave but is not expected to reach property," Mr Blewman said.
Civil Defence is working with Environment Waikato and Mighty River Power to monitor river levels. Waikato Stadium had been put on standby in case of any evacuations.
Evacuation would not be considered unless the river reached 16.5m. At 16.1m, some surface road flooding was possible.
Riverside walkways had already been submerged.
"We are continuing to talk with residents and keep them informed of the situation," Mr Blewman said.
- additional reporting from NZPA
