Anticyclones of Autumn

Issued by MetService at 01:24pm 08-Mar-2004
Anticyclones of Autumn

The prospects are great for another fine weekend. March is bringing with it a regime change in the weather pattern. The February pattern that fostered the deepening of lows over New Zealand has been replaced by one that allows anticyclones to linger over the country.

"This switch in weather regime has occurred at the time many consider to be the start of autumn", commented MetService Weather Ambassador, Bob McDavitt. "Autumn is a transition time between the heat of summer and the chill of winter. March is the month when the seas surrounding the country are at their warmest and the winds within the roaring forties are at their quietest."

The calm settled weather in autumn anticyclones helps to build a haze over the plains, and longer cooler nights brings misty mornings. The Indians on the Great Plains of North America used this season for hunting and from this comes the phrase "Indian summer".

According to McDavitt although the new regime is tamer than what we had in February it will not stay dry all the time. "As one anticyclone moves away and its replacement moves in, there is usually some wind and rain with the accompanying trough and front."

MetService has issued a warning for heavy rain between Otira and Doubtful Sound from fronts on Tuesday and Wednesday,and is maintaining a weather watch for rain over the headwaters of the lakes and rivers of Otago and Canterbury. The associated trough should bring showery weather to many eastern areas on Wednesday and Thursday, followed by settled weather in time for the weekend.

ENDS

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