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Towards the South As leading skippers skirt around the
St Helena High, November 27, 2000 With the leading pack of skippers clear of the doldrums, the field has spread across a broad front with Ellen MacArthur and Kingfisher to the west, Catherine Chabaud and Whirlpool to the east and leader Yves Parlier smack dab in the middle. All are sailing well, with Parlier reporting 14 to 15 knots of sailing speed and even Chabaud waiting for a lull in the trades to inspect her mast-top before she gets into the Southern Ocean. MacArthur, with Roland Jourdain aboard Sill keeping close watch, is playing her game conservatively, confident that her westing will yield good winds around the perimeter of the anti-clockwise spinning South Atlantic High pressure cell, otherwise known as the St Helena High. Parlier - the consistent 'middle man' in this race, has stuck to his route from well before the doldrums, and despite losing his main halyard and spending nine hours repairing it, remains in front - much to the chagrin of his closest rival, Michel Desjoyeaux aboard PRB, who has shadowed Parlier from the start. Cheeky Chabaud The big surprise for all concerned is Chabaud's cheeky easterly route through the doldrums, across the equator and now into the south-east trade winds on 'the other side'. The eastern route isn't supposed to yield results. It might save miles in a power-boat race, because the shortest route to Cape Town and the Southern Ocean is, indeed, well to the east. Trouble is, the wind isn't there. Uh, er, rather, it isn't supposed to be there. Chabaud cites a 20 knot easterly as her savior and her key out of the Inter-Tropical Convergence Zone. Whatever the case, it appears that cloud activity across the zone was well spread out north and south, and east to west, giving skippers in the 20 to 30 degree west longitude similar conditions, when averaged out over the three days they were stuck there. Race co-ordinator Philippe Jeantot, notes that the passage through the doldrums took longer than in the last Vendee Globe in 1996, reducing the leading yacht's advance over the last race from three days to just one. All eyes on the South Atlantic Now, all eyes are on the South Atlantic and how best to cut the corner of the St Helena High, with the aim of gaining access first to the Southern Ocean and her relentless westerly winds. Based on the results of virtually every other 'round the world race, those who enter the westerlies first have an excellent advantage over their rivals. It will be very hard indeed to make up time lost in light winds in the sub-tropical Atlantic.
Weather observations for November 27, 2000 Image courtesy of OceanWeather South Atlantic pressure above, and cloud activity below, shows plenty of wind between a trough of low pressure off Argentina and the St Helena High to the east. Skippers in the Vendee Globe 2000 will hope to cut the corner of the high if a low develops out of this cloud band trough. If the cloud band stays put, skippers will find themselves sailing well to the south to maintain favourable winds. Meanwhile, an upper trough between southern Brazil and a low south of Cape Town is creating lighter conditions on the surface directly below it. What will be the outcome for Vendee Globe sailors? Image courtesy of Intellicast.
Fleet positions Leading yacht positions as of November 27. Note the St Helena High to the south and east. Picture courtesy of Virtual Spectator. Cloud band development Of particular interest is the strengthening of a semi-permanent cloud band, extending south east from southern Brazil into the South Atlantic. It is a 'long-wave' cloud band, or trough of low pressure, delivering warm and moist tropical air well south of the St Helena High. It can be a source of storms, but more importantly, its stable position tends to squeeze the St Helena High into a skewed position, with plenty of north-westerly wind flow directed into the Southern Ocean. If this trough line continues to develop, skippers will have a sleigh ride into the deep south. If it degenerates, and the high spreads across the Atlantic basin, light winds and constant sail-changing will be the order of the day. We all wait with baited breath!
Image courtesy of Intellicast. The South Atlantic, animated intermittently from November 15-23, 2000. This image starts with the south-east cloud band in a mature phase, with low pressure west of Cape Town which would have helped yachts entering the Southern Ocean - had there been any of them there at the time! During the sequence the cloud band fades, leaving the St Helena High to meander across the Atlantic basin from Africa to South America with plenty of light airs in between. In the later frames of the image the cloud band strengthens, pushing the sub tropical high to the east and creating stronger winds along the boundary between cloud band - or low pressure trough - to the west and the high to the east. © weather-wise.com 2000 Explore comment from the Sunday, November 26: "The Saint-Helen high pressure system seems to be lower
than usual. Its center is located around 30° South and 10° West.
To avoid it, the competitors will have to go further down before turning to the
East. Yves Parlier (Aquitaine Innovations) still leading the race has gone
through 10° South. He still has more than a thousand miles to sail
to reach this point, roughly three days. Until then the centre of the high
pressure has time to move and oblige the skippers to modify their strategy to
turn left earlier. The leading boats don¹t have any more South Easterly winds
and with the Eastern lift the competitors are now beam reaching with 15 to 20
knots of wind. It is ideal conditions. Yves Parlier was telling us this morning
: « I am doing 14-15 knots! I am ¹eating¹ the miles and I am happy. I am on a
beam reach, the boat is sailing really well and the sea is calmer. I am doing
some maintenance »." |