21-Sep-2006
Equinoctial Gales
MetService meteorologists are forecasting more bursts of northwesterly winds on Saturday and Monday. These will bring
hot dry and gusty conditions to all eastern districts, more periods of heavy rain to the western slopes of the Southern
Alps, and blustery winds to Wellington.
"We had a burst of the northwest winds last night and this morning", commented MetService Weather Ambassador, Bob
McDavitt. "The air that brings heavy rain to the South Island's West Coast warms as it descends the eastern side of the
mountains. This explains the 18 degree Celsius temperature recorded by MetService at dawn today at Kaikoura."
"This spring's equinox is on Saturday and after that the days are longer than the nights. The Southern Hemisphere
tropics are warming as the sun comes southwards while Antarctica is at its coldest time for the year. The westerly winds
in the 'roaring forties' feed off the difference in temperature between the tropics and Antarctica, so it's no surprise
they're strong and widespread at the moment. Because of this, they are sometimes referred to as 'equinoctial gales'."
The persistent west to northwest flow over New Zealand is bringing bouts of heavy rain to the Southern Alps with another
coming this weekend. People in Otago and Canterbury will find the fire danger exacerbated by the hot dry and gusty
conditions.
ENDS