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Southern Ocean window Animated surface pressure maps from December 7-10, 2000
This animation shows how low pressure cells move under the St Helena High, west of Cape Town. The high is centred well south at the moment and it is interesting to see how the high is affected by these lows pushing in from the south. Below Madagascar, between 30-60 degrees east, is an area where the St Helena High and the Indian Ocean High butt up to each other. It is a bit of a dead zone, where low pressure seems to falter and winds are light and variable (in terms of the Southern Ocean anyway). The Vendee Globe leaders are in this area now - as of December 14, 2000. While some skippers are lolling about in this fickle region, they might take heart knowing that this zone also produces storms and if skippers are to the north of its epicentre, they will benefit from tail winds. Weather router Bob Rice calls this zone a 'cyclogenesis' area. "In the southern hemisphere there is more water, things move faster," he says. "You always have to keep an eye to the north looking for cyclogenesis areas creating zones of low pressure." "The life cycle of these storms are fairly short. They can go from an open wave to a fully occluded storm in a day or two." Other cyclogenesis areas are:
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