CYCLONE GABRIELLE

Georgina Griffiths : MetService meteorologist

A nationwide State of Emergency was declared on 14 February, as Cyclone Gabrielle lashed the North Island – only the third time such a declaration has been made in New Zealand’s history.

The declaration was issued to support six regions that had already declared a Local State of Emergency: Northland, Auckland, Tairāwhiti Gisborne, Bay of Plenty, Waikato, and Hawke’s Bay.

This cyclone was a very intense system even after coming out of the tropics, with an analysed central pressure of 965hPa (see MetService expert forecaster hand-drawn analyses in Figures 1 and 2). With such a deep central pressure, this system produced a large area of severe gales, dangerous seas and extreme swells of 9–12 metres, as well as a significant storm surge (of at least 0.5m) along the northern and eastern coastline of New Zealand.

In addition, extreme rainfall totals (approximately 200–500 millimetres of rainfall) affected all northern and eastern areas of the North Island, resulting in loss of life, widespread and unprecedented flooding, and an extreme number of slips across the motu. Many rain gauges across the north and east North Island recorded near to, or more than, half their annual rainfall total in just the first 45 days of the year (see Figures 3, 4 and 5).

MetService forecasters had issued multiple Red Heavy Rain Warnings and multiple Red Wind Warnings, well in advance, for this cyclone. Red warnings are reserved for only the most impactful weather systems, which are expected to cause loss of life, significant impact, and significant disruption.

Cyclone Gabrielle has certainly delivered an unprecedented blow to the North Island, and from us here at MetService to you out there cleaning up, at home or on the farm, kia kaha.

the five years (2019 to 2023). The annual average rainfall accumulation is shown in black. The year-to-date rainfall accumulation (722 mm) as at 9am 14 February 2023 was over half (56 %) of the usual annual rainfall tally, just 45 days into the year

The annual average rainfall accumulation is shown in black. The year-to-date rainfall accumulation (540 mm) as at 9am 14 February 2023 was around half (48 %) of the usual annual rainfall tally, just 45 days into the year

A LARGE AREA OF SEVERE GALES

EXTREME SWELLS OF 9-12 METRES

EXTREME RAINFALL OF APPROXIMATELY 200–500 MILLIMETRES last years (2019 to 2023). The annual average rainfall accumulation is shown in black. The year-to-date rainfall total at Napier Airport was 483mm, or 60 % of the usual annual rainfall tally, just 46 days into the year