Covering period of Monday 17th -Thursday 20th February

‘Warm and moist’ is the name of the game this week with a swath of tropical air over Aotearoa New Zealand. Rain, associated with a low-pressure system from the north, continues to fall on the North Island today (Monday). The Coromandel Peninsula to the Kaimai Range, and Gisborne/Tairāwhiti north of Tolaga Bay are under Orange Heavy Rain Warnings until 8 and 9pm respectively today.  

MetService Meteorologist Katie Hillyer says, “We’ve already seen 200mm of rainfall recorded at the Pinnacles on the Coromandel Peninsula over the last 24 hours, which, even given the exposure of this mountainous station, is very impressive.” MetService expects a further 70-90mm of rain to fall in those areas today.    

High humidity will be felt across the North Island too. “Warm humid air with plenty of cloud cover acts like an insulative blanket, meaning warmer nights and uncomfortable sleeps this week,” says Hillyer. The poster child of this effect being Rotorua, who only saw a 2°C difference between their maximum yesterday and their minimum this morning. Honourable mentions to Whanganui and Hawkes Bay, where temperatures are set to crack 30°C over the next couple of days - a distinct change to the cool summer they’ve experienced in the east thus far.    

Overnight, the main action switches from northeastern areas of the North Island to the South Island with rain associated with an approaching low-pressure system from the Tasman Sea. The Ranges of the Tasman District have been upgraded to an Orange Warning, with 80-100mm expected to fall between 9pm tonight and 7am tomorrow. A Heavy Rain Watch is also in place for the Richmond and Bryant Ranges. Rain will spread into eastern parts of the South Island tomorrow morning, soaking some of those dry soils.    

“Thunderstorms could also be on the cards Tuesday afternoon and evening for Canterbury down to Southland, as well as Westland through to Buller,” warns Hillyer. Periods of rain will continue across much of the country through to Thursday, with today and Tuesday being the most active days.  

 “Cloudy and wet will be the real descriptors for much of the country until Thursday and into Friday, when a ridge of high pressure starts trying to push out that humidity and bring in some fresher air,” says Hillyer.  

Please keep up to date with the most current information from MetService at http://www.metservice.com/national/home

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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