Covering period of Thursday 25th – Sunday 28th May – The cold start to Thursday will be quickly forgotten as we move into the weekend, with MetService expecting a rise in temperatures across the country, and heavy rain and strong winds for the West Coast of the South Island. By Saturday night showers also affect the Far North, moving south over the North Island and turning to rain on Sunday.
Clear skies overnight led to the observation of low temperatures and frosts by a good portion of Aotearoa on Thursday morning, with locations such as Christchurch, Masterton, Waiouru, and Twizel dropping below zero in the early hours of Thursday.
“A narrow ridge of high pressure formed over Aotearoa on Wednesday, bringing a brief period of calm weather, especially about central New Zealand,” MetService meteorologist Clare O’Connor explains.
This respite is short-lived however, as MetService have issued Orange Heavy Rain Warnings for the West Coast of the South Island – including Fiordland, and the headwaters of the Canterbury lakes and rivers. Strong Wind Warnings have also been issued for the central and eastern South Island, beginning on Friday morning.
“A strong, moist, northwesterly flow made landfall over Fiordland early Thursday morning, and will slowly spread northwards over the South Island on Friday, bringing heavy rain for western areas of the South Island. Severe gales are expected about the Canterbury High Country, the southern Lakes, and Central Otago, with gusts of up to 120km/h possible in exposed places”, O’Connor details. “This flow is pushing that narrow ridge northwards, so while this is all going on down south, the rest of New Zealand will see a settled Friday and most of Saturday.”
On Saturday as the wind and rain eases in the South Island, another low pressure system approaches the northern North Island, however, the low (bringing rain) is weaker relative to last week’s storm. This weather system brings warmer temperatures, especially to the North Island with locations such as Whakatane and Hamilton potentially reaching 15 degrees overnight Saturday into Sunday, eight degrees above their average for this time of year.
O’Connor elaborates: “Currently this system is tracking further south than what we experienced last week, so while it will be felt across a larger portion of the country, forecast rainfall amounts and wind speeds are less.”
With no chance to dry out from last week, already saturated ground in those northern areas is still at risk from even a small amount of rain and residents are advised to keep up to date with MetService’s Severe Weather Watches and Warnings over the weekend, as well as the advice from local authorities.
For media enquiries or to arrange an interview with one of our meteorologists please call 04 4700 848 or email metcomms@metservice.com
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
