‘This is how to get a basic weather forecast in just 15 minutes’ – British Sailing Team meteorologist, Simon Rowell

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Author: Nicole Borg

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March 25, 2022

Ever since 2015, Simon Rowell has been working as the meteorologist for the British Sailing Team. Speaking  to Yachting.mt, Malta’s freshest charter and brokerage company, Simon went into detail on how someone that is not a qualified meteorologist can also get their own weather forecast if they’re attentive enough.

But first, let us introduce you to Simon! Asked to tell us a bit about himself, Simon said: “Since 2015 I have been the meteorologist for the British Sailing Team. Forecasting at the Olympics & Paralympics in Rio and the Olympics in Tokyo was fantastic, if rather challenging.  I have also been the forecaster for the Clipper Round the World Race since 2011, with other clients ranging from superyachts to ocean rowers to TV production companies, and land based sports such as cycling, rugby & golf.  I have been a yachting professional since 1997, starting off as an instructor before working for Clipper Ventures both as a round the world race skipper on the winning boat in the 2002 race and as assistant race director in charge of the day to day operations and all the skipper and crew training for the 2005 race.

I am an RYA Ocean Yachtmaster Examiner and spent two years as Chief Instructor at UKSA in Cowes before going back to university in 2009 to study meteorology at the University of Reading, finishing the MSc course in 2010 with a distinction and a dissertation investigating how hurricanes start in the North Atlantic.

Before all this I spent seven years as an electrical engineer on oil rigs in various usually insalubrious parts of the world.

Yachting.mt, got in touch with Simon in order to shed some insight on how yacht owners, captains and skipper (and anyone with a mere interest in sailing), could learn to get their own weather forecast. Simon explained that one doesn’t need to formally study meteorology to be able to predict the weather, but they surely need to pay attention. “Most Captains & Deck Officers are a lot better at this than they think they are – being rained on a lot does help,” he went on to say.

This is how to get a basic weather forecast in just 15 minutes according to weather expert Simon Rowell

This is how I get a basic forecast to use throughout the day, and it only takes 15 minutes through the Mark 1  eyeball, one of the best weather observation tools around.

STEP 1

I’ll get myself a mug of tea, go outside and watch the sky.  It will take a few slurps of tea for the grey matter to kick in, but then I’ll start to notice things. I first check out what sort of sky it is and in which way it is moving. I check out the clouds – are there lots, is the sky covered, is it raining? Then I check out in which way they are moving – this is a great way to look at the overall synoptically driven wind. In the early morning, especially the air at the surface, may be disconnected from the movement above and it will take a bit of heating for the synoptically-driven wind to mix its way down to the surface.  

STEP 2

Once I’ve got this worked all of that out, and finished my tea, then I’ll go and look at the bigger picture. The clouds I’ve just seen will be part of a larger synoptic feature, a depression or a high pressure system perhaps, so I’ll look at the synoptic charts to see what’s with us now, the most recent analysis chart, and the next available forecast charts. I do this to get an overall context. As an example, the high wispy clouds that have just looked lovely in the morning light may well be the first clouds ahead of an incoming warm front. Then I’ll look at the latest satellite image, and most national forecast agency websites (e.g. the Met Office, NOAA in the US or MeteoFrance) let you see this overlaid with the rainfall radar at regular intervals. This allows me to see that the features on the chart are backed up by what’s actually happening – really important. Excluding the time taken to brew my tea, this has taken about 5 minutes.

By now I’ve developed my idea into something like this – “there’s a cold front forecast, it’s over Dartmouth now and if I look at the rain radar it’s taken 4 hours to get there from Lands End so I reckon I’ve got about 6-7 hours before it gets to me”.  This is really useful info, and is based on real observations.  My personal favourite source of UK weather is the Met Office, so I’ll then go to their website and get the hour-by-hour conditions for where I happen to be.

STEP 3

However I’d like a second and even a third opinion, and also to see surface wind charts, which I can’t do with the Met Office.  I’ll now go onto an app that I’ve used before and understand.  By understand, I mean that I know where they get their source data from, when they get it so that it’s not too out of date, and a vague idea of what processing they apply to get the better resolution they claim.  There are many, and most of them get their data from NOAA (the US equivalent of the Met Office).  Some get it from ECMWF (the European Centre for Medium Range Weather Forecasts based in Reading). Both are professional and sensible choices, and both have their own forecast model separate from the Met Office so make for good independent comparisons.  With most of these sources they have free & “professional” options – before you shell out, have a good look at what your money gets you, and ask yourself whether you both need & understand what that is.  If the answer to either of those is “no”, then stick to the free version.

This comparison is very important – if all 3 data sources say roughly the same thing, then I’m going to be confident that the forecast is of good quality.  If all 3 say something different then my confidence in the forecast goes down – and this is a really useful bit of information, as it will affect your sailing strategy.  Also, a low confidence forecast makes the use of your physical observations (looking for clouds, feeling a change in air temperature, watching rain come in) even more important.

One thing to remember with “high resolution” forecasts is that they are only as good as the models that underpin them.  In the Rio Olympics the single most important feature was Sugar Loaf, at what was usually the windward end of the Medal Race course.  This is a 396m high dome-shaped rock – but it’s less than 1km wide and doesn’t show up at all on any of the land models used for weather forecasting!  This is not a criticism, it’s a function of a computer model. In general the smallest thing that can be simulated by a model is 3-4 times the size of the grid used.  This means that a 1km resolution forecast won’t see anything that is less than about 3-4 km across.

Photo by Dom Tidey

STEP 4

Back to my 15 minute forecast – by now I’ve got a good idea of what’s forecast to happen through the day weather-wise, which I’ll write down in a few lines.  This needs to include how things will change visually as the systems come through – e.g. it’ll rain with the front but probably not before it arrives.  I’m up to 10 minutes now.

The thing with sailing near land is that a lot of the weather features are what I like to call “sub-grid”, i.e. they’re caused by land features which, as we’ve seen, don’t show up on the weather models.  A very effective way to do this is to look at Google Earth with your forecast, and work out if the incoming wind may go through any gaps and around or over any obstacles. This should allow you to predict, for example, acceleration up the east side of Carrick Roads with a SW; the way a W tends to turn in to a WNW going down Southampton water; and that in a strong E it’s best not to leave Largs with too much sail up even if there’s only 10 kts in the marina.

You might also want to think about the character of the breeze too – and by this I mean whether it’s going to be all puffy & shifty, or steadier.  The expected clouds will give you a clue for this.  If it’s a steady offshore day for example, then the expected cloud is light & puffy cumulus, spreading as the land heats up – this in turn will give a patchy & shifty breeze underneath it, but generally returning to the mean direction.

In the warm sector of a depression you tend to get fairly featureless stratus clouds – however, looked at from above this tends to come in waves, and on the surface underneath that you tend to get bands of pressure moving with the breeze.

…more from Simon

Now that you have all the knowledge on how to get  your own weather forecast in just 15 minutes you might be interested in learning more about the weather! Don’t fret, Simon has just the thing for you. His book, “Weather At Sea” comes from a fairly intensive 1 day weather course he put forward aimed at people who already earned a living at sea but wanted to know more. The book goes through weather from global to regional to local scales, with the aim of helping its readers both understand the mechanisms behind the weather & how to forecast it better.

Or better yet, you can request Simon’s expert advice on weather routing, pre-voyage planning, general queries, weather tuition, weather background studies, expert witness services and more. 

“If you have a question about weather, especially (but not exclusively) if it’s water-related, please ask. You can get in touch via my website or Instagram (@simon_rowell_weather),” concluded Simon.

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