Weather for the Route du Rhum

Meteo France's Sylvian Mondon how he is working prior to the start with Safran IMOCA 60 skipper Marc Guillemot

Unlike the Ultimate multihull class, routing is not allowed for the IMOCA monohulls competing in the Route du Rhum–La Banque Postale. So how is Safran skipper Marc Guillemot preparing to deal with the weather in this race? By working with Sylvain Mondon, a forecaster with Météo France, who has had an amazing series of successes: he was router for Lionel Lemonchois, when he shattered the race record in 2006, and later for Franck Cammas' Groupama 3, when earlier this year she set a Jules Verne Trophy record around the world.

What is the most likely weather scenario in this Route du Rhum – La Banque Postale?

SM – The two basic patterns are firstly a series of low-pressure areas moving across the North Atlantic, which force skippers to pass through several fronts in a row, or alternatively there will be a high-pressure area stuck over the British Isles. The first scenario requires a lot of strategy, while the second means we can look forward to a race where speed is most important to reach the Trade Winds. After that, the crossing itself will involve downwind sailing at moderate or high speed. In the final stretch, there is often a lot of uncertainty: will the trade winds be present or not? Will there be thunderstorms? … The goal is to avoid calms and areas where there is too much wind or the seas are too heavy. Sometimes, this means choosing the least bad option.

What are the dangers and the greatest difficulties?

When the major weather patterns are well established, we can deal with them. It becomes more complicated for example with fronts, which can disappear or divide to form a second front. In those cases, we look at the data, which helps us to understand what is going on according to the visible elements and the tools that Marc has at his disposal, but that can only be done at the last moment just before the start… Apart from that we need to analyse thousands of different scenarios, which never does the skipper any harm.

How do you prepare beforehand with Marc?

From the start of the season, we get to grips with the weather tools on board (Navimail and Synboat - two Météo France software programs). But most of the work was done four years ago [in the Route du Rhum 2006], and today, we’re really updating that knowledge. On top of that, we’re studying the commonest situations, like the ones people experienced in the last race. For example, on the day of the press conference for the Route du Rhum - La Banque Postale, we studied the 2006 race for the IMOCA boats. We have a debriefing after each major race: that is part of the long term training. When preparing for a race, we always rely on previous races. It’s work that lasts throughout the season.

What about during the week leading up to the start of the race?

From Thursday (28 October - the race starts on Sunday 31 October), we start to look at the conditions for the first few days of racing and as time goes by, we look further and further ahead. Day after day we look at the weather elements, where the forecasts are the most stable. According to each element, we deduce the way to tackle the weather and find the right route and identify the moments, when there will be choices to make. If the forecasts are not stable, we try to identify the tricky areas where there is most at stake.

Do you show Marc certain points that he needs to pass?

No, not at all! I don’t give him a detailed route with waypoints. That’s not my role. Instead, we talk through the way the systems are evolving. It’s a real discussion, over and over again to ensure that Marc remembers the moments and the important systems. For example, he must avoid going for a rest at a moment that is strategically important four or five days ahead in the race. From the outset of our work together, Marc and I have always worked that way. We talk things through and discuss everything in front of the screens looking at the various models.