Cyclone Gabrielle – Extreme rain and winds impact New Zealand, unprecedented rainfall totals expected in some areas

Despite being downgraded from a tropical cyclone, Gabrielle is intensifying and spreading strong winds and heavy rain across a wider area affecting the whole of the North Island in some way.

• This is an ongoing extreme and impactful event. People could lose power or become isolated. Listen to local authorities and your local Civil Defence and know where your local evacuation center is
• The entire North Island is under a severe weather warning, with Northland, Coromandel, Auckland, including Great Barrier Island, on the highest wind alert – a MetService Red Warning
• Extreme rain and wind are expected for many North Island regions, accompanied by phenomenal seas along northern and eastern shores, and significant storm surge near, and slightly in advance of, the centre of the cyclone
• For some, rainfall totals will be unprecedented. Flooding and slips will increase as the event unfolds. Rivers and streams will rise rapidly

Gale-force winds and intense rain caused power outages and travel disruptions across the North Island on February 12, 2023. Winds of up to 90 km/h (56 mph) have been recorded in several areas, including Kaitaia, Purerua, and Kerikeri, while Cape Reinga, a more exposed site, recorded wind gusts of 140 km/h (87 mph). Waves of nearly 11 meters (36 feet) have been reported at the Bay of Islands.

Lisa Murray, Head of Weather Communications, explains that the worst-affected areas can expect between 350 – 450 mm (14 – 18 inches) of rain, wind gusts of 120 – 140 km/h (75 – 87 mph), and dangerous waves and coastal inundation, especially at high tide.¹

MetService Red Warnings for Heavy Rain are in place for Northland, Auckland, Tairāwhiti Gisborne north of Tolaga Bay, and Coromandel, with Orange Warnings for Heavy Rain in place for Bay of Plenty, the rest of the east coast of the North Island, and parts of Marlborough, including Kaikoura.

“The wind of this strength combined with rain means rain could be almost horizontal making it very difficult to walk in, and rain could get under the eaves of houses, adding to the flooding risk. This is a really extreme and impactful event. People could lose power or become isolated. Listen to local authorities and your local Civil Defence and know where your local evacuation center is,” adds Lisa.

Despite being downgraded from a tropical cyclone, Cyclone Gabrielle is still incredibly impactful and is intensifying, spreading strong winds and heavy rain across a wider area affecting the whole of the North Island.

This is an unfolding situation and forecasts will be updated – so it is important to stay in the know, MetService said.

This extreme weather event comes just 2 weeks after North Island experienced extreme rainfall and widespread flooding and destruction in which 4 people lost their lives.

In late January, Auckland experienced extreme rainfall and severe flooding that rendered thousands of buildings in the region uninhabitable. The Auckland area recorded its wettest month in at least 170 years, with the Auckland Airport receiving 245 mm (9.65 inches) of rain in a day, surpassing the previous daily record by over 50%.²

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 New Zealand’s MetService is ‘torrential’, which is defined as 40 mm (1.57 inches) of rain or more in an hour.

The flooding has put the public’s focus on nature-based alternatives to traditional stormwater systems, according to NIWA Urban Aquatic Scientist Dr. Annette Semadeni-Davies.

References:

¹ Impacts already felt from Cyclone Gabrielle – MetService – February 12, 2023

² Thousands of buildings in Auckland unsafe for living after worst rains in 170 years, New Zealand – The Watchers – February 8, 2023

Featured image: Cyclone Gabrielle at 03:50 UTC on February 12, 2023. Credit: NOAA GOES-West, Zoom Earth, The Watchers