Severe Weather Outlook
Valid from Monday 01-Mar-2021 to Thursday 04-Mar-2021
Issued: 2:06pm Saturday 27 Feb 2021
A ridge of high pressure moves away to the east on Monday, as a trough approaches from the Tasman Sea, preceded by a moist northeast flow. This trough should cross the country on Tuesday, followed by unsettled showery northwesterlies.
There is low confidence of warning amounts of rain about the ranges of Buller and western Nelson on Monday and Tuesday, and also Mount Taranaki on Tuesday.
For Westland and northern Fiordland there is low confidence of significant heavy rain on Monday, then moderate confidence Tuesday and Wednesday, with low confidence Tuesday and Wednesday for the remainder of Fiordland.
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.
High confidence:
a 60% likelihood (or 3 chances in 5) that the event will actually happen.
New issues of this forecast are made available on this site at or before 16:30 NZST
Thunderstorm Outlook
Valid to Midnight Saturday, 27-Feb-2021
Issued: 8:40am Saturday 27 Feb 2021
Valid to Noon Sunday, 28-Feb-2021
Issued: 8:25pm Saturday 27 Feb 2021
Valid to Midnight Sunday, 28-Feb-2021
Issued: 8:25pm Saturday 27 Feb 2021
Severe Thunderstorm Criteria
In New Zealand, MetService classifies a thunderstorm as severe if one or more of the following criteria are met:
Heavy rain (from thunderstorms):
Rainfall of 25 millimetres per hour, or more.
Large hail:
Hailstones 20 millimetres in diameter, or larger.
Strong wind gusts (from thunderstorms):
Gusts of 110 kilometres per hour / 60 knots or stronger.
Damaging tornadoes:
Fujita F1 (wind speeds greater than 116 kilometres per hour / 63 knots) or stronger.