The Albany tornado which yesterday killed one man and injured 15 people may not turn out to be the nation's most costly in financial terms.
The twister slammed through the $77.5 million Mega Centre shopping precinct, near Westfield's $205m Albany Mall on the North Shore, before moving south leaving a 5km trail of destruction.
Civil Defence officials said 27 properties had been damaged, 20 of them 11km south of Albany in Roseberry Avenue, Birkenhead - just across the Harbour Bridge from the central city - where one of the homes was uninhabitable.
It was not yet known whether the damage bill would exceed the one million pounds for New Zealand's worst recorded tornado - equivalent to $68m in today's dollars - which killed three people and damaged or totally destroyed nearly 200 shops and houses at Frankton in Hamilton West, in 1948.
The Albany twister may also have an impact on reported plans by the ANZ National Bank to make $32.5m from selling Argosy Property Management, which runs the listed Argosy Property Trust.
The bulk retail centre - sited between a former Placemakers store and The Warehouse and opposite the Westfield shopping centre - had Farmers, Briscoes, and Rebel Sport, among its 26 other retail tenancies.
Yesterday's tornado was the second fatal twister to hit the area in 20 years.
In May 1991, a tornado hit Albany, lifting roofing iron from homes and destroying a small church on the southwestern side of the suburb, and bulldozer driver Wayne Stanley-Hunt died when he was hit by debris.
Damaging tornadoes around Auckland have a return period of about two or three years and other incidents have included damage to buildings and power lines (August 1980; May 1982; September 1986; August 1992; March 1997), and up to 50 houses were damaged in August 1992. Tornadoes damaged fences and trees in August 1980; September 1986; as well as August 1992.
Frankton was the nation's worst tornado in terms of casualties, injuring 80 people, seven of them badly, as buildings were lifted from their piles, roof iron and chimneys were snapped off, trees uprooted and power and telephone lines were left dangling.
Reports at the time said the air was filled with flying corrugated iron, branches of trees, timber and other debris. Heavy rain accompanied the storm, with lightning and thunder.
Another two people Rosina Dawn Wikohika, 55, of Levin and her grandson Gary Mason, 10, were killed with a tornado destroyed a farmhouse at Motunui, about 16km northeast of New Plymouth in 2004, and three of their relatives were seriously injured.
Tornadoes are a mass of unstable air rotating at up to 244km/h and yesterday's was estimated to have had windspeeds of around 200km/h.
"We've had reports of cars lifted and thrown, roofs taken off and trees uprooted, which is consistent with...winds averaging somewhere between 180kmh and 220kmh," said WeatherWatch website analyst Philip Duncan.
Tornadoes occur frequently in Auckland but are usually much smaller than the large devastating ones that roar across in the midwest of the United States, according to civil defence officials.
The National Institute of Water and Atmospheric Research (Niwa) has estimated the nation averages about 20 to 30 tornados each year, but most of them are relatively small and are typically very narrow - with damage paths estimated to average 18 metres - and have short tracks.
Experts have said that only about a third of them occur near people and are reported.