CHRIS TIBBS ON SOUTHERN OCEAN STORMS
{ Chris Tibbs is a meteorologist and weather router. He has sailed over 300,000 miles, including three round the world races }
A ny colour you want as long as it’s grey! That’s my overriding memory of life in the Southern Ocean – we tend to forget the sun reflecting off icebergs and the aurora of the Southern Lights on the horizon at night, because it is the relentless succession of lowpressure systems rattling around the world that dominate the weather.
This gives periods of low cloud and rain to be followed by an active cold front and squally conditions. A temporary lull may occur as a ridge of high pressure builds... .before the next low is upon us and the pattern repeats until we escape from the area.
For many sailors the Southern Ocean is the holy grail of racing, with its reputation for fearsome storms and monster waves. But what makes it different from other storms and oceans? The remoteness, for one: knowing that the only help you’re likely to get is from other competitors and at times you’re closer to the International Space Station than any other person (beyond fellow competitors). The Oceanic Pole of Inaccessibility is at 48° 52.6’S and 123° 23.6’W and is the point on the globe furthest from any land (over 1,400 miles) – and it feels it!
I have been fortunate to race around the world three times; twice in the Whitbread Race and also as skipper in the BT Global Challenge (racing the wrong way around the world) and the depressions were bigger and fiercer than others I have experienced in other parts of the world.
Racing strategy indicates heading south to reduce the distance along the great circle route, and also to take advantage of the circumpolar current that continually circles the globe, without getting south of the low pressure systems and into head winds. In the days of the heavy IOR yachts of the early Whitbread races, the more wind you had the faster you went, with the cold and ice being the limiting factors. Modern around the world races now have ice limits to prevent yachts getting too far south and into the areas where icebergs are known to be (though the Jules Verne record attempt does not); in addition modern racing yachts will go faster in lighter wind strengths and sea states.
Lows develop from different air masses coming together but not mixing, giving the different sectors of a depression quite different characteristics. Warm tropical maritime air will give low cloud, rain and drizzle with poor visibility, then as you are overtaken by the cold front this gives way to squalls with hailstones likely and gusty conditions. Post-front showers and squ
