08/08/2024 

Thursday and Friday will be wet in the North Island and cold in the South Island to end the week. These dreary conditions may be forgotten by Sunday, as MetService forecasts warmer and drier weather.

Thursday evening in the west of the North Island from Auckland through to Wellington, as well as the Coromandel Peninsula and western Bay of Plenty, will be wet and come with a risk of thunderstorms, heavier showers, and small hail.

In the South Island, vehicles travelling over the central alpine passes on Thursday afternoon and evening are likely to see snowflakes, and Road Snowfall Warnings in force along State Highway 73. The summits of both Arthur’s Pass and Porters Pass are forecast to receive a few centimetres of snow due to cold southerly air combining with moist northerlies over the central South Island. The west of the South Island takes the brunt of the moist northerly flow with a wet Thursday afternoon there but will dry off this evening and stay that way until Sunday.

MetService meteorologist Clare O’Connor elaborates, “While ski fields in the area may appreciate the fresh top up ahead of the weekend, the rain along the eastern coast of the South Island will feel bitter this evening as southwesterly winds pick up there. However, a brighter day dawns for most on Friday as western North Island showers are gradually quashed and the South Island rain is pushed northeast over the day by a building ridge of high pressure.”

A different story over the eastern North Island as rain sets in there early Friday morning. Heavier rain as well as thunderstorms are expected in the Raukumara Ranges in the afternoon. Although the forecast amount of rain is not sufficient to require a Heavy Rain Watch to be issued, Gisborne and Napier are already sitting around half of their average August rainfall only one week into August, so extra care should be taken around waterways and any area at risk of surface flooding.

On Saturday, any showers lingering around the North Island gradually clear throughout the day, including those in the east. With an expected maximum temperature in Wellington of 13°C, rugby fans heading to Sky Stadium Saturday evening are advised to dress warm as cold southerly winds could still be blowing through Cook Strait.

The weekend ends on an unseasonable note in Canterbury and Otago, with mild westerlies coming in on Sunday, pushing temperatures about 4°C above average for this time of year – a trend that continues into the week ahead.

Understanding MetService Severe Weather Warning System

Severe Thunderstorm Warnings (Localised Red Warning) - take cover now:

• This warning is a red warning for a localised area.
• When extremely severe weather is occurring or will do within the hour.
• Severe thunderstorms have the ability to have significant impacts for an area indicated in the warning.
• In the event of a Severe Thunderstorm Red Warning: Act now!

Red Warnings are about taking immediate action:

• When extremely severe weather is imminent or is occurring
• Issued when an event is expected to be among the worst that we get – it will have significant impact and it is possible that a lot of people will be affected
• In the event of a Red Warning: Act now!

Orange Warnings are about taking action:

• When severe weather is imminent or is occurring
• Typically issued 1 - 3 days in advance of potential severe weather
• In the event of an Orange Warning: Take action.

Thunderstorm Watch means thunderstorms are possible, be alert and consider action

• Show the area that thunderstorms are most likely to occur during the validity period.
• Although thunderstorms are often localised, the whole area is on watch as it is difficult to know exactly where the severe thunderstorm will occur within the mapped area.
• During a thunderstorm Watch: Stay alert and take action if necessary.

Watches are about being alert:

• When severe weather is possible, but not sufficiently imminent or certain for a warning to be issued
• Typically issued 1 - 3 days in advance of potential severe weather.
• During a Watch: Stay alert

Outlooks are about looking ahead:

• To provide advanced information on possible future Watches and/or Warnings
• Issued routinely once or twice a day
• Recommendation: Plan

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