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Weather forecasting is a very specialist subject. Generally speaking, weather forecasting is beyond the reach of even most professional yachtsmen. We simply do not have the resources onboard our vessels. The UK Met Office has one of the biggest and most powerful computer ever made (Cray 2 Super-computer, capable of some 14 thousand, Trillion calculations per second!)

The UK Met Office is one of only two truly global forecasters, the other is the USAs NOAA (National Oceanic and Atmospheric Administration) these two organisations monitor and attempt to accurately forecast the weather of the world.

For you and I onboard our vessel at sea, we are not really forecasting the weather. We are trying to apply the forecast to the weather around us. It rarely fits perfectly as the forecast is produced for a very large area (The Northern Atlantic Ocean, for instance) and we are only interested in just a couple of thousand square miles of the forecast area. Even if you are Coastal sailing and are using the Met Office (or other agency's forecast) you will still be dealing with a forecast that covers a lot of sea. The Met Office inshore forecast for the area North Foreland to Selsey Bill and 12 miles offshore. The straight line distance is 136 Miles x by 12 miles = 1632 square miles of forecast area. It is unreasonable to expect the same weather or sea conditions to exist across this huge area.

In very general terms I like to have three forecasts available. The idea is to plan for the worst forecast and hope for the best forecast. For my three forecasts, I would choose a Government Agency, (the UK Met Office for instance), I would then want a commercial weather service, (you can use an App for this one, maybe Predict Wind or similar) and thirdly I would look for some form of local service (Local Radio, TV or a local weather web site) 

Here in Brittany I still use the Met Office, Predict Wind and I tie this in with my weather station at home. 

Some basic knowledge of the Jetstream can also be of use. Most of us know that the Jetstream is a high-level fast-moving river of air that helps Airliners fly faster. What we, perhaps, don't know is that the Jetstream also acts as a barrier between the very cold polar air masses and the warmer Temperate air masses. Thus if the Jetstream moves South (as it does in the Winter) then the colder Polar air can also move South.

Because the Jetstream is this FAST moving river of air, it's pressure is also lower than the surrounding air. This lower pressure makes it very attractive to depressions, in fact, the Americans frequently refer to the Jetstream as the "Storm Track".

If you know where the Jetstream is forecast to be, then you also know where the depressions are likely to be.

There are a few good Jetstream forecasts on the web. Most will go up to 5 days ahead.

Check out the Jetstream forecast at www. Choose the North Atlantic, Big Images, then animate.

There are some useful web sites that can be of great help also.

One of my favourites is

There are links to the UK Met Office MSLP (Mean Surface Level Analysis) charts (5 Days worth) A satellite view of Northern Atlantic and Northern Europe, this allows me to see the current cloud formations and apply what I am seeing to what the forecast shows. Differences between the forecast timing and the actual timing help me to correct the forecast to a local scale.

Whilst site is focused on the Northern Hemisphere if you are sailing the southern seas then have a look at

This is a weather site focused upon sailors and explorers. Nice clear charts and good animations.


There are some excellent books on the weather at Sea;

RYA Weather Handbook, a decent book with much good information, easy to read and a good guide

The Sailor's Book of the Weather, (Simon Keeling). A very good first book of the weather. Simon Keeling has done a great job with this book. 

Instant Weather Forecasting, (Alan Watts) The essential starter for anyone interested in weather and it's local effects. This book comprises a series of pages, each has a photo of the sky and on the facing page is the description of what is happening and what is going to happen. IDEAL FOR DAY SKIPPERS AND YACHTMASTER OFFSHORE ALIKE


The WEATHER Handbook, (Alan Watts) A superb book for those with a little knowledge. An easy way to develop that little knowledge to a greater level.

Weather for Sailors, (Bill Biewenga). Published by North ISBN 0-9744676-0-X. An advanced book for Sailors. This book presumes a good level of weather knowledge to start with. However, it does contain some excellent pieces on analysing the upper atmosphere, 300mb and 500mb charts in particular. A favourite of mine.


REEDS MARITIME meteorology, (Maurice Cornish & Elaine Ives) a superb book covering every aspect of forecasting and weather when at sea. One of my favourite books.

The SEABREEZE HANDBOOK, (Alan Watts) Sea Breeze are difficult to predict, harder to understand and can transform a coastal passage. This book gives you all the knowledge you need to manage the Sea Breeze.

Additional books that specifically mention weather would include Tom Cunliffe's Heavy Weather Cruising and Adlard Coles Heavy Weather Sailing. Both should be required reading for all yachtsmen both Power and Sail.








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