Updated 12:17pm — As the incoming low continues to deepen over the Tasman Sea, the threat for heavy rain later today, tonight and tomorrow continues increase for the upper and central regions of the North Island.  Parts of the South Island could also see heavy rain.

The regions that will most likely see the heavy rain are:

North Island

• Northland
• Auckland
• Coromandel Peninsula
• Bay of Plenty
• Waikato
• Taranaki

South Island

• Nelson
• Westland
• Canterbury
• Otago

Of these regions, the North Island’s Bay of Plenty and the eastern ranges of the Waikato…and the South Island’s Nelson and eastern Otago are likely to see rain reach warning criteria.  For that reason, government forecaster MetService has issued Heavy Rain Warnings for these areas.  MetService feels that rainfall totals could reach up to 120mm between tonight and tomorrow afternoon for all but eastern Otago.  Rainfall totals of up 70mm is expected with additional heavy rain expected on Tuesday.

The other regions listed above are still being watched for the possibility of rainfall totals reaching warning criteria.

It is important to note that about parts of the upper North Island, there is still a lot of saturated ground for last week’s heavy rain.  Surface flooding and slips could easily develop.

Thunderstorms are possible later today and tonight about Northland, Auckland and the northern Coromandel peninsula.  Strong winds, hail and a few weak tornadoes may accompany any thunderstorms that develop.

Strong winds are expected across much of the North Island and upper South Island.  Winds could reach gale force.  Severe gales are possible in exposed parts of the western North Island from Northland to Wanganui…as well as the South Island’s Nelson on Sunday into early Monday.

By WeatherWatch Analyst Howard Joseph