Auckland sets new all-time daily rainfall record
Late Friday afternoon, Auckland saw three times its average January rainfall in 3 hours. 153mm was the top 3 hourly fall recorded in the region, with many areas topping 120mm. The January average is of the order of 60-80mm.
According to New Zealand's National Institute of Water and Atmospheric Science (NIWA), many of these centres set new all-time daily rainfall records. The city's airport had to close when the main terminal was inundated with floodwater.
The cause of the rain was a low pressure system of tropical origin. Swollen with the intense humidity typical of the tropics, the low moved southeastward from its initial position over the Coral Sea last weekend, to reach the North Island of New Zealand on Friday, as seen in the water vapour imagery above. The slow-moving nature of the low exacerbated heavy rainfall totals.
From 3am to 9pm Friday, rainfall totals of over 250mm were recorded in the Auckland region, which is close to the average total summer rainfall. The top fall, according to NIWA, was 260.6 mm over the northeast suburb of Albany.
Moisture plume: incoming! 💧
— NIWA Weather (@NiwaWeather) January 25, 2023
A sub-tropical moisture plume (🟣) isn't what Auckland ordered for its anniversary weekend but Mother Nature didn't get the memo 🤦♂�
From Friday, it looks warm, humid, rainy & stormy + heavy rain/possible flooding in sodden parts of the North Island. pic.twitter.com/G5ePz3vH8F
Image: From NIWA. Moisture levels predicted on Wednesday for Friday afternoon.