Covering period of Monday 8 – Thursday11 May – Tropical air and all its moisture moves off mid-week but MetService warns there is a lot of rain to come before it departs. Then a cold front ushers in wintery weather.
The feed of air from the tropics which brought warm temperatures to Aotearoa/New Zealand and heavy rain to western and northern areas over the past week is set to depart. However, before it moves away an intense period of rain and thunderstorms is expected to move quickly across Aotearoa on Tuesday, affecting already sodden western and northern areas of both islands.
MetService Meteorologist Jessie Owen says, “The band of rain is currently lying over the West Coast of the South Island. It will reinvigorate today into a very active system so when it moves back across the country tomorrow it will bring a burst of very heavy rain to those same areas that have been affected over the last week. ”
Heavy Rain Warnings and Watches are in place for northern and western parts of both islands, the same places which have already seen large accumulations of rain over the last week. A Severe Thunderstorm Watch has been issued for Northland, and Auckland and the Coromandel Peninsula will come under thunderstorm watches as well. People are urged to stay up to date with the watches and warnings here bit.ly/AllWarnings which are updated routinely every day mid-morning and in the evening.
The rain band will be moving quicker this time around, so most regions will only see a few hours of wet weather. It will however be very intense rainfall and there is the potential for localised torrential rainfall rates with thunderstorms. Owen says, “This very heavy rain will be falling on already saturated ground, so impacts such as surface flooding, rising rivers, and slips are likely.”
Following the exit of the tropical air, a low-pressure system from the Tasman Sea and a cold front southwest of New Zealand both reach the country on Wednesday. This drops temperatures significantly as far north as Kaitaia, and brings further rain and strong winds, as well as snow to low levels. Snow is expected to lower to about 400 metres over the South Island on Wednesday, and about 800m over the central North Island on Thursday.
Owen says, “This colder air is expected to spread right up the country, bringing a distinctly wintery feel. Wellingtonians should only expect a maximum of 10°C on Thursday, five degrees lower than the expected low of 15°C overnight Monday.” This will be a very noticeable change after a mild start to the month.
Understanding our Severe Weather Watches and Warnings
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
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
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
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!
