The presence of a low level jet (LLJ), or strong wind in the lower atmosphere, combined with tropical moisture to create persistent heavy rain in the Auckland area on Friday, January 27, 2023, resulting in widespread severe flooding, destruction and casualties.
- Many locations in Auckland recorded their wettest day on record — receiving approximately an entire summer’s worth of rain in one day
- Auckland officials described it as a devastating rain event, culminating in the declaration of a state of emergency
- At least three people have lost their lives and one remains missing
Rain in Auckland began before sunrise and there were steady falls through the day. An Orange Heavy Rain Warning was active all day, with a risk of thunderstorms and downpours which began to come to fruition during the afternoon. MetService issued several Red Thunderstorm Warnings as the torrential downpours continued to spread over Auckland, leading MetService and Auckland Council to jointly elevate the warning for the entire region to a Red Heavy Rain Warning.
MetService meteorologist, Angus Hines, says, “The rain that fell around the Auckland region was extreme and unprecedented.”
The weather station located at Auckland Airport has an unbroken record of weather observation since 1962 and prior to Friday, the wettest ever day there amounted to 161.8 mm (6.37 inches) of rain.
On Friday, that same site reported 245 mm (9.65 inches) of rain, surpassing the previous record by over 50%.
Other weather stations around the region also reported remarkable rainfall, with many spots noting between 250 – 300 mm (9.84 – 11.81 inches) of rain within the day. Some stations even reported over 80 mm (3.15 inches) of rain in an hour.
To put this into context, the highest classification for intense rain at MetService is ‘torrential’, which is defined as 40 mm (1.57 inches) of rain or more in an hour.
The heavy rain has led to widespread, severe flooding in the region.
Three people have lost their lives while one person is still missing.
Two were found dead in Wairau Valley on Auckland’s North Shore – one in a culvert and a second in a flooded car park – and a third body was found later after a landslide hit a house in the city centre. Another man is missing after being swept in a community south of Auckland.
Many areas in the North Island have also been drenched in the last few days. Some locations, such as the Coromandel Peninsula, Northland, and Gisborne are in the midst of their third heavy rain event of 2023.
“Due to the recent rains, it didn’t take long before the impacts of the current severe weather began to rear up again. Slips, road closures and surface floods are common around much of Te Ika-a-Maui/North Island at the moment. People are advised to minimize travel where possible, and if you must travel, then check in with Waka Kotahi/NZTA to see the latest road closures,” says Angus Hines.
Following the unprecedented rain for the Auckland region, MetService is warning of further rainfall for Auckland, although nothing is likely to match the severity of what has happened in the past 36 hours.
The MetService Red Heavy Rain Warning was lifted this morning and showers with the chance of thunderstorms are forecast for the remainder of the day (Saturday). The State of Emergency still remains in force for the region. There is a MetService Heavy Rain Watch in place for more rain on Sunday, January 29, from 06:00 LT until midnight.
“The main rain band has moved off to the east of Auckland for the time being and there are a number of Orange Warnings and Watches in place around the North Island,” Hines said. “The main rain band returns to Auckland and Northland later on Sunday but rain will come and go for many areas in the North Island.”
While the upcoming rain should not match the intensity of what has been, impacts are expected to be severe and wide-reaching because of the saturated ground. More flooding will occur through many northern regions in the coming days, and people should stay abreast of the latest information from local emergency management, Civil Defence and metservice.com.
1 Unprecedented rain in Auckland, with more on the way – New Zealand Met Service – January 28, 2023
2 NIWA Weather – January 27 and 28, 2023
3 New Zealand flooding: three dead and one missing as Auckland hit by record rainfall – The Guardian – January 28, 2023
