Shipping Forecast Explained
Gale warnings, synopsis, sea areas: the fixed pattern of the Met Office bulletin and the exact meaning of every word in it.
Read the Shipping Forecast in the order it is spoken: gale warnings first, then the general synopsis, then the sea areas one by one, each with wind, sea state, weather and visibility in that order. Once you know its fixed vocabulary, a line such as "Southwest 4 or 5, increasing 6 to gale 8. Moderate or rough. Occasional rain. Moderate or good" becomes a precise forecast.
The bulletin in order
Issued by the Met Office and broadcast on BBC Radio 4, the Shipping Forecast is issued four times a day, at 2300, 0500, 1100 and 1700 UTC, with each issue covering the following 24 hours from 0000, 0600, 1200 or 1800 UTC respectively. Radio broadcast times have changed over the years, so check the BBC schedule for the current ones.
The forecast always begins with the gale warnings in force, meaning winds of force 8 or more. Next comes the general synopsis, which describes the main pressure systems and how they are expected to move. Then come the sea-area forecasts for the next 24 hours. Areas with similar conditions are grouped together, so the groupings change with the weather, and some bulletins end with reports from coastal stations and the inshore waters forecast.
The waters around the British Isles are divided into 31 sea areas, read clockwise from the northern North Sea: Viking, North Utsire, South Utsire, Forties, Cromarty, Forth, Tyne, Dogger, Fisher, German Bight, Humber, Thames, Dover, Wight, Portland, Plymouth, Biscay, Trafalgar, FitzRoy, Sole, Lundy, Fastnet, Irish Sea, Shannon, Rockall, Malin, Hebrides, Bailey, Fair Isle, Faeroes and Southeast Iceland. Trafalgar, off south-west Spain, is included only in the late-night broadcast, and the Met Office publishes a map of all 31 areas.
Decoding the language
Wind direction is the direction the wind blows from, and its strength is given as a Beaufort force. Gale means force 8 (34–40 knots), followed by severe gale 9, storm 10, violent storm 11 and hurricane force 12. "Veering" is a clockwise change in direction, such as south-west to west; "backing" is the opposite, anticlockwise, such as south-east to north-east. "Becoming cyclonic" means a big change in direction as a depression crosses the area.
The other key words have exact meanings in the Met Office glossary:
| Term | Meaning |
|---|---|
| Imminent / soon / later | within 6 hours / 6 to 12 hours / more than 12 hours from time of issue |
| Visibility: good / moderate | more than 5 nautical miles / 2 to 5 nautical miles |
| Visibility: poor / very poor | 1,000 metres to 2 nautical miles / less than 1,000 metres |
| Sea state: smooth / slight / moderate | waves under 0.5m / 0.5–1.25m / 1.25–2.5m |
| Sea state: rough / very rough | 2.5–4m / 4–6m |
| Sea state: high / very high / phenomenal | 6–9m / 9–14m / over 14m |
| Pressure systems: slowly / steadily / rapidly | under 15 knots / 15–25 knots / 35–45 knots |
Reading it in practice
Take the example above. "Southwest 4 or 5, increasing 6 to gale 8" means a south-westerly moderate to fresh breeze strengthening to a gale during the 24 hours. "Moderate or rough" means waves of roughly 1.25 to 4 metres, "occasional rain" is the weather, and "moderate or good" means you should see at least 2 nautical miles.
For a passage, write the forecast down against a map of the sea areas, then check the latest version and any new gale warnings on the Met Office website before setting out. Coastal sailors, paddlers and kitesurfers should also read the separate inshore waters forecast, which covers the sea up to 12 miles offshore.
