Severe Weather Outlook

Valid from Tuesday 07-Apr-2020 to Friday 10-Apr-2020

Issued: 3:07pm Sunday 5 Apr 2020

A front moves slowly northeastwards over the South Island on Tuesday, before weakening as it moves across the North Island on Wednesday. This front is preceded by a period of northerly rain and followed by a west to southwest flow across the country through to Friday.

There is moderate confidence of warning amounts of northerly rain in Fiordland and south Westland early Tuesday morning, and for the remainder of Westland later on Tuesday.

The westerly flow is expected to strengthen in the far south on Friday. There is low confidence of westerlies becoming severe about coastal Clutha and Southland including Stewart Island on Friday as depicted on the chart.

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 Sunday, 05-Apr-2020

Issued: 7:53am Sunday 5 Apr 2020

No thunderstorms or significant convection expected during this period.



Valid to Noon Monday, 06-Apr-2020

Issued: 9:46am Sunday 5 Apr 2020

No thunderstorms or significant convection expected during this period.



Valid to Midnight Monday, 06-Apr-2020

Issued: 9:47am Sunday 5 Apr 2020

No thunderstorms or significant convection expected during this period.



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.