Centre » Notable Weather
Events Archive » 1996/1997
29-31 December 1996
A deep depression, former Tropical Cyclone Fergus, moved southwards over the North Island at the end of December bringing torrential rain, widespread flooding and slips to exposed northern districts. The storm occurred during the peak of the Christmas/New Year holiday period, disrupting the plans of many people who were forced to evacuate their traditional vacation sites.
Major road damage occurred in Northland and Coromandel Peninsula and it wasn't until 3 January that most roads closed by the storm had reopened. It was estimated that another 6 months work would be required to bring the roads back to how they were, at a total cost of about $2 million. The Coromandel Peninsula (where a state of civil emergency was declared) was hardest hit, being isolated for a time. Hundreds of holiday-makers sought shelter in Civil Defence centres throughout the region, while water supplies in Pauanui and Whitianga were also cut.
In Northland, an elderly man drowned on New Year's Eve in a creek swollen by the heavy rain of the past two days. While rain caused most of the problems, severe gales also occurred in parts of Bay of Plenty and Gisborne, bringing trees, phone and power-lines down and damaging property.
Tropical Cyclone Fergus originated over the seas just south of the Solomon Islands and was first named on 24 December. From there it moved southeast and reached a peak on 28 December while passing between Vanuatu and New Caledonia. At this stage winds were estimated to be averaging 80 knots (148 km/hr) near the centre, but fortunately the cyclone didn't cross any major island groups.
By now the cyclone was presenting a threat to New Zealand, as its predicted track had it headed towards northern parts of the country, and warnings were issued by MetService for heavy rain and gales in northern districts. These warnings were continually updated throughout the event and well publicised.
The subsequent movement of the cyclone over the North Island is shown in the following maps.
Mean sea level pressure analyses for midday NZDT 29 December to midnight NZDT 31 December 1996 in 12 hour intervals.
A shallow trough of low pressure and moist northeast flow preceding the cyclone meant that by the morning of 29 December, rain had already set in from Northland to Bay of Plenty. The ground was becoming saturated even before the full force of Fergus had arrived!
As the broad cloud-sheet to the south of the cyclone consumed the North Island, the rain gradually became persistent and heavy, and by 9am NZDT on the 30th falls exceeding 100 mm in 24 hours were recorded in parts of Northland.
On the 30th, the cyclone (now termed a deep depression) moved quickly south to lie in the Bay of Plenty in the evening (see maps). Although the cyclone filled from 970 hPa to 986 hPa by midnight on the 30th, it still brought torrential rain to exposed northeastern parts of the North Island, especially the Coromandel Peninsula, where Whitianga recorded 241.8 mm in the 24 hours to 9am on the 31st. The Gisborne district also received heavy rain, with falls exceeded 250 mm in the ranges over the same period. The highest rainfalls measured over the period of the storm were reports of 425 mm in the Thames - Coromandel district.
While winds over Northland and Auckland were generally not as strong as expected, parts of Bay of Plenty and Gisborne experienced severe gales on the 30th due to the strong easterly flow around the southern side of the depression.
On the 31st, the depression moved quickly away to the southeast of New Zealand, to the south of Chatham Islands, and conditions eased.