Severe Weather Outlook Get File

Severe Weather Outlook

Issued : 2:58pm Sunday 20 Sep 2020, Valid from Tuesday 22 September 2020 to Friday 25 September 2020

A front, preceded by strong northwesterlies, is expected to move onto the South Island from the southwest on Tuesday, then northeastwards over the country during Wednesday and Thursday. It is followed by a complex trough of low pressure over the lower South Island from the Tasman Sea during Thursday and Friday. The front is expected to bring periods of heavy rain to western areas, and gale northwesterlies to the east from Tuesday through to early Thursday. The trough is forecast to bring a period of heavy rain to Fiordland late Thursday and early Friday.

There is high confidence of rainfall accumulations approaching warning criteria in Fiordland and Westland from later Tuesday to about midday Wednesday, and moderate confidence for Buller and the western ranges of Nelson on Wednesday, but low confidence for the Tararua Range on Wednesday. There is also low confidence of warning amounts of rain in Taranaki about and north of the mountain, Taumarunui, Waitomo and Taupo during Wednesday and Thursday, and in Fiordland on Thursday.

In addition, there is moderate confidence of northwest gales becoming severe in exposed parts of Southland and Otago on Tuesday, and high confidence for inland Canterbury, Wellington and Wairarapa including Tararua District during Tuesday and Wednesday. There is moderate confidence of severe northwesterly gales in exposed places of Marlborough during Tuesday and Wednesday, but low confidence about Hawkes Bay and Gisborne during Wednesday and Thursday.

Probability/Confidance Map

Low confidence: a 20% likelihood (or 1 chance in 5) that the event will actually happen.
Moderate confidence: a 40% likelihood (or 2 chances in 5) that the event will actually happen.
Good confidence: a 60% likelihood (or 3 chances in 5) that the event will actually happen.

Image Valid Till Noon Tuesday 22 Sep 2020
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