28/11/2024

Covering period of Thursday 28 November - Monday 2 December

After a spell of high temperatures across Aotearoa New Zealand, MetService is forecasting cooler conditions to start the weekend in the wake of a southerly change.

Rain and wind affect the South Island today (Thursday) as a cold front moves north over the island through this afternoon and evening. Northwesterly winds strengthen ahead of the front before switching to cold southerlies; a Strong Wind Watch is in force for Otago and Southland until 7pm this evening.

MetService meteorologist Ngaire Wotherspoon elaborates, “This moist northwesterly flow over the Southern Alps is a classic setup for the foehn effect, where rain on one side of the mountain means warmer and drier winds on the leeward (other) side. We’re already seeing hot, windy conditions in the east, while in the west there is heavier rainfall with a Heavy Rain Watch in place for Fiordland.”

Temperatures are expected to reach the high 20s for Canterbury and Otago, with a high of 29°C forecast for Timaru and 28°C for Christchurch. The southerly change passing through this afternoon and evening will mark significant drop in temperatures for both regions, as well as a sprinkling of rain. Timaru may struggle to reach the mid-teens on Friday, with a high of only 16°C forecast.

Northwesterlies also become strong and hot over the lower North Island this afternoon, with a Strong Wind Watch set to take effect for Wairarapa and southern Hawke’s Bay at 3pm, and Hastings and Wairoa are both forecast to hit 30°C.

The front moves on to the North Island early tomorrow, spreading a band of scattered rain and cooler temperatures as far north as Rotorua before stalling.

Wotherspoon remarks, “Rain from this weakened front sticks around over the North Island for the weekend, clearing on Sunday night. Down south the weekend is looking sunnier, with temperatures starting to warm up again on Sunday as we head into summer.”

MetService’s Canterbury weather radar is back in action today after undergoing a complete replacement over the past nine weeks. The new radar will provide improved services to communities in the Canterbury region. The radar imagery is very popular on metservice.com and the MetService weather app.

Note:

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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