1 to 4cm of snow per hour. Visibility less than 500m. More than 4cm of snow per hour. The Basics Hills, valleys, and buildings strongly influence the strength and direction of wind. Air flows over the ground like water down a stream, ducking and diving over hills and dales, forming eddies in the shelter of the ranges, with fast flowing sections through narrow gorges and around the end of mountain chains.
Wind is made up of a series of gusts and lulls.
The speed given in the forecast represents an average wind speed typical of the area as a whole. Where MetService expects differences from this average value to be to be large we may give a likely gust speed, or refer to places that are particularly exposed. The wind direction in forecasts identifies the direction from which the wind comes. A northerly wind comes from the north, while a northwest wind comes from somewhere between north and west. The term variable refers to winds coming from no particular direction it does not refer to the wind speed.