Vendée Globe

With a ridge of high pressure stretching right up to the Bay of Biscay from the Azores high, the wind off Madeira is a 20-knot easterly on the leeward side and 20-knot NE'ly between the islands and the continent of Africa.

This pattern of trade winds is set to remain in place until the start of the weekend. This difference in angle is going to lead to a wide range of trajectories: those, who are furthest west will continue on a SSW bearing, while those to the east will get closer to Africa (bearing of 180°).  The first group will be at least 100 miles off the islands (Madeira, Canaries, Cape Verde) to avoid the effects of the mountains allowing them to reach the Doldrums on one long thousand mile tack! The second group will be trying to stick with the direct route by staying close to the coast of Mauritania, where stronger NNE'ly winds are forecast. They will need to do a series of gybes and deal with the Venturi effects (strengthening of the wind between the islands) and wind shadow around the Canaries, which stretch out for more than 300 miles in longitude…
 
However, another influence is likely to upset these strategic plans: a stormy low is forming this  week-end a long way off between the Canaries and the West Indies. This will cut through the trade winds, which usually blow between Africa and the Caribbean, weakening the flow or even upsetting the whole tropical pattern  for two days or more.  As it is difficult to create models for this type of low, it could stretch out, disappear, move eastwards or northwards... The sailors have a hard choice ahead involving two factors: favouring an option where they stay in close contact keeping each other in check or a strategy, which will involve them taking an option lasting several days. Head for the Canaries or aim to stay a long way off the islands avoiding the stormy low?

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