Update: 11:07AM MetService has widened the area expected to bear the brunt of the heavy rain and severe gales being brought to New Zealand this weekend by Tropical Cyclone Lusi.
In a severe weather watch issued just after 10am today, it added Bay of Plenty and northern Gisborne to the areas expected to get “significant heavy rain”.
Areas previously identified as likely to be hard hit were Northland, Auckland and the Coromandel Peninsula.
“This will be a significant adverse weather event, affecting large parts of northern and central New Zealand,” MetService said.
At the time Lusi was rated a category 3 storm and was southwest of Fiji and heading south. The cyclone is expected to move out of the tropics tomorrow and to bring severe weather to many regions of New Zealand during the weekend.
For farmers with parched paddocks in many parts of the North Island there are concerns the rain from Lusi may be too intense to provide much benefit.
The weather could also threaten Christchurch which is particularly vulnerable after heavy rain on Tuesday and Wednesday last week caused widespread flooding. The threat of flooding in the city is thought to have increased as a result of earthquake-induced ground deformations.
“Rain and easterly gales are expected to spread onto northern New Zealand from later on Friday, and southwards across the remainder of the North Island on Saturday, then to the upper and eastern South Island later on Saturday and Sunday,” MetService said.
Significant heavy rain was likely in Northland, Auckland and the Coromandel Peninsula late Friday or Saturday, and for Bay of Plenty and northern Gisborne on Saturday.
Easterly gales were likely to become severe in those areas, and were also expected to spread to Waikato, particularly near the Kaimai Range, and the Central Plateau.
“For the remainder of the North Island and upper/eastern South Island, expect a period of heavy rain during the weekend, especially in regions exposed to the east and northeast,” MetService said.
“Easterly gales are likely in many places, and the risk of these becoming severe is highest in the lee of ranges, such as the Tararuas, Richmond Range, and the Tasman Mountains.
“Although severe weather is likely, at this stage there is still uncertainty regarding the track of the low and exact areas that will be affected.
“At the time the watch was issued, Lusi was expected to track just west of the North Island on Saturday, before crossing the south Island late on Sunday.
Despite the amount of rain being predicted, it could be of little benefit to farmers desperate for rain in many North Island areas, Federated Farmers adverse events spokeswoman Katie Milne said.
“When it’s been dry for a long time you need rain to come in gently for a couple of days, so the ground gets used to being wet again,” she said.
“If it comes in hard and fast it will just run off and you don’t get the benefit.”
In some places the ground was “a bit like concrete”.
“Anywhere that gets a huge downpour on hard surfaces that are not able to absorb the moisture, it just runs off and causes flooding and perhaps takes a bit of topsoil with it.”
In Christchurch, emergency management officials met yesterday afternoon to discuss the threat from Lusi, and were drawing up a contingency plan in case more heavy rain fell this weekend.
