‘Considering the speed that phenomena evolve in the Doldrums a little luck is always needed’ – Vendée Globe meteo adviser Christian Dumard annexes his prediction for the Vendée leaders’ passage of the ICTZ with a warning.
Even with all of the tools and assimilated knowledge, no doubt enhanced during last winter and spring’s lockdown learning phase in Europe, the passage of the Inter Tropical Convergence Zone’s unexpected squalls, prolonged calms under clouds, and variable, shifting winds – is always a time of high tension for Vendée Globe skippers.
But for the tightly matched leading group of six skippers, time micro-analysing the latest files, data and images, is every bit as important as keeping the boat fast.
On the latest models the doldrums are more active than expected. The critical convection zones have grown and become more numerous. The skippers need to watch the evolution and the movement of these cells which are not small isolated squalls, They can quickly and unexpectedly grow to be several tens of miles or even several hundred miles.
To monitor these the skippers use real time satellite images which show large clusters of clouds. Forecast models have improved a lot and can model areas with light winds better now, as well as the areas with the risk of heavy rains. Big clouds usually mean heavy rain, wind convection and calms are possible with strong gusts at the edge of the clouds. They can look to thunderstorm forecasts from the European Prediction Center. This index has only been available for a few years. They can and will look at currents that can bring warmer waters which create more convection and as well convectivity indices provided by the models.
Weather expert Dumard notes, “The models are not all created equal. The finer the mesh the better the forecast. It must also take into account the temperature of the water as well. In this game, the data from the European model (ECMWF) which offers a resolution of 9 km, available to the public on Windy, is often the most efficient.”
Charlie Dalin and Louis Burton have a west-east separation of just 25 miles late this afternoon. In fact Burton is further north than the nominal leader Dalin on Apivia while the skipper of Bureau Vallée 2 is quicker all the time as the two yellow-hulled IMOCA’s reach northwards in an SE’ly trade wind at speeds around 19-20kts.
At the time of writing it was probable that Burton would lead across the Equator early this evening, marking something of a triumphant return after the skipper lost miles to the peloton repairing at Macquarie Island and going on to round Cape Horn in ninth more than 550 miles behind Dalin. And it will be the second time in consecutive races that this boat has led the Vendée Globe back into the northern hemisphere after 2016-17 winner led, en route to victory.
Computed to be just a couple of miles apart in terms of distance to the finish line at Les Sables d’Olonne’s Nouch Sud buoy, the two leaders saw Germany’s third placed Boris Herrmann re-adjust his track to the west overnight and this morning. He has picked back up to speed, pacing Burton at just over 20kts, but still promoting speculation that Herrmann might not, after all, have all his sail inventory intact.
Speaking of Herrmann on this afternoon’s Vendée Globe Live show in English Charlie Dalin said:
“He is positioning for the doldrums and maybe the scenario afterwards, the doldrums will be a bit less active further west but after that it is harder to say, but we will see who is right in 36 to 48 hours. We will see. We should be out or nearly out. I believe he has a full foil and is a strong contender in to the finish but I don’t believe any boat is at 100 per cent of its potential. I don’t believe he will be at 100 per cent, everyone will have their problems, sails, electronics, hydraulics. I think everyone has some problem at this stage of the race.”
Source: Sail World