Abnormal low pressure system brings extreme weather to Australian stations

Spring and early summer at Australian Antarctic stations saw some unusual weather patterns. December 2001 at Davis was the station’s third windiest month on record.

Included in its extreme weather was the station’s first recorded December blizzard (gale-force wind, horizontal visibility less than 100m). December also saw records broken in numbers of gales (12), days of snowfall (18) and days of blowing snow (6).

Mawson had nearly three times the normal number of blizzards in November and December, and half again as many gales (31) as usual. Casey, by contrast, had much less boisterous weather — strong winds and gales were well down on normal — and days of snowfall in December 2001 were about half the long-term average.

Atmospheric pressures at Mawson and Davis provide some insight into the unusual weather: surface atmospheric pressures in December 2001 at Mawson were 10hPa below normal and at Davis 4hPa below average with a very strong northerly wind anomaly at Davis and over Prydz Bay. Throughout the three months of October to December, depressions were south of their normal paths.

Hugh Hutchinson, Bureau of Meteorology, Hobart