Weather guru, Chris Tibbs talks about the skills and information you need to have a successful eastbound Atlantic crossing
Atlantic crossings are usually spoken of in terms of days of running west before the tradewinds (although as sailors we are rarely satisfied and yearn for an angle to turn the dead run into a reach!). An eastbound Atlantic crossing towards Europe poses a different set of issues, but also some good sailing, as we head north into disturbed westerlies.
Leaving the Caribbean we head north through the horse latitudes (30°N) where the Azores high ridges towards Florida and the wind becomes light and variable.
Once through this ridge we should be able to follow a route north of the high in mainly westerly winds, but far enough south to avoid gales from depressions passing to the north.
It is not possible to give an exact latitude where we find the westerlies as it changes. Lows develop and move north-east, displacing the Azores high and allowing the stronger wind to migrate southwards.
This pushing of the high south will give a succession of lows split by transient ridges of higher pressure, then an acceleration in the wind as the next low passes.
The driving force for this is the jetstream steering the lows, and also depends on how well established the Azores high is. If the jet stream is north then a good passage will be had, but if it dips to the south the lows will be more aggressive tracking close to the route and giving stronger winds.
This balance between the lows and the high pressure depends on the time of year as the jet stream will usually migrate north in the summer and south in the winter. It is an extension of the weather we get in the UK; as the summer progresses we lose the more aggressive lows and the Azores high becomes better established.
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If this were the only factor, then a passage back to Europe in the summer would give a warmer and lighter wind passage. But – and it is a big but – hurricane season starts at the beginning of June and, while it is possible to come back in hurricane season (with good weather routing and a fast boat), most insurance companies will not cover the passage as it is high risk.
This makes picking the moment for a passage a case of waiting for the worst of the winter storms to have blown through, but leaving the tropics before the hurricane season.
We are seeing some trends to the hurricane season and over the past five years named storms have occurred before the official start of hurricane season in every year. These have been tropical storms and, while relatively small affairs compared with hurricanes; they still pack a punch with winds between 34 and 63 knots.
In general these early tropical storms develop east of the Bahamas and track north. With many yachts traditionally leaving the Caribbean at the end of April, the increase in early season storms need to be taken into consideration when setting off.
Whether heading for Europe or the USA a May departure is usual. Due to the easterly trade winds we are initially pushed north, sailing on starboard tack on a comfortable beat/fetch.
Some years this can last most of the way until reaching the westerlies, but other years will see yachts pushed almost to Bermuda before a more easterly course can be followed.
This gives a mixed weather pattern with low pressure passing close to the north, we must also watch for active cold fronts leaving the coast of the US, tracking east and over our route. It can be quite active weather-wise as warm, moist air pushed north from the tropics comes up against the colder, drier air from the north-east.
This generates an area of cyclogenesis where lows develop and deepen, and we will often see lows develop to the west of the route near Cape Hatteras. Once developed, they track to the north-east, leaving us in the more changeable wind south of the low.
To stop or not on an eastbound Atlantic crossing?
While this can give some varied sailing, it is also rewarding and one of the rewards along the route is the places to visit. Bermuda may be the playground of the rich but it is also an interesting island steeped in history; whether to call in or not depends on personal choice and also how far north we are pushed.
I have, on an eastbound Atlantic crossing, been pushed north of the islands, but we can usually cut the corner and head east before we get close, particularly if time is an issue.
In normal times, the Azores are a must-do destination, and as all eastbound Atlantic crossing routes pass close to them it would be a shame not to stop. However, due to restrictions caused by COVID yachts may have to give Bermuda and/or the Azores a miss.
Some yachts, if heading for the UK or Northern Europe, will sail non-stop anyway, to shorten the distance.
The further north we are pushed by the trade winds when we leave the Caribbean the more we can shorten the distance if heading for the UK. However, there is always a trade-off and in this case it is the North Atlantic lows. As the lows tend to develop somewhere near Cape Hatteras they will then track north-east, passing between Newfoundland and the Azores.
Therefore the further north we get while we are still west of the Azores the closer we will be to the centres of the lows. By this time, usually late May or early June, we can still get some large and deep depressions passing close to the route so the further north we are (while west of the Azores), the more likely we are to experience strong wind and gales.
Even if we are making an eastbound Atlantic crossing from the USA it is usual to head south-east at first and, while we can use the tail of the Gulf Stream for a boost, it is safer to get south of the Gulf Stream into warmer waters (less fog) and to head towards the Azores staying on the south side of the lows rather than risk the headwinds on the northern side.
Azores to Europe
Once at the Azores our passage to northern Europe depends on waiting for a good forecast and hitching a ride on a low pressure system passing to the north-west. This will generally need a short hitch north to clear the Azores high before a fast run home.
Heading for the Mediterranean should be more straightforward, with light winds near the Azores becoming strong northerlies as we approach Europe. These are from the Portuguese trade winds generated between the Azores high, and semi-permanent low pressure over Spain, which is a feature of spring and summer.
Out of season passages are possible but there are concerns with them. Early departures run the risk of gales near the latitude of the Azores. North of Bermuda and north of the Azores the chance of gales in March are up to 15% of the time, as shown on the US Pilot Charts, dropping in April and significantly reducing in May. The North Atlantic in winter is not really the place for yachts, particularly if sailing for pleasure.
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