Editing Nor'west arch (section)

==Occurrence==
The nor'west arch can be seen as far north as [[Amberley, New Zealand|Amberley]] and as far south as [[Central Otago]], but it is at its most prominent on the [[Canterbury Plains]], due to the flat and low-lying nature of the land to the east of the mountains.

The nor'wester can blow at any time of year, but is less common in winter. Many of the strongest northerly and northwesterly winds blow ahead of [[cold front]]s. A front lying across the South Island will often extend from northwest to southeast, reaching northern parts of the [[West Coast, New Zealand|West Coast]] before it reaches corresponding areas on the east coast. The steep air pressure gradient ahead of the cyclonic system associated with a front gives these nor'westers their strength; they will commonly reach [[gale]] force and cause isolated damage to trees and buildings.<ref name="RNZ_64745">{{cite news |url=http://www.radionz.co.nz/news/national/64745/dunedin-homes-without-water-as-wind-topples-trees |title=Dunedin homes without water as wind topples trees |date=21 December 2010 |work=[[Radio New Zealand]] |accessdate=1 November 2011}}</ref> Once every few years, a nor'wester will approach [[hurricane]] strength and cause widespread damage.