Reading a bulletin: the shipping forecast format
1The lesson in plain words
Read warnings, synopsis, then forecasts. In the UK shipping forecast, each area gives wind, sea state, weather and visibility.
Bulletin layout
World Meteorological Organization (WMO) rules give high seas bulletins three parts: warnings, a synopsis and the forecasts. National products can use different elements and ordering. The UK shipping forecast is one example to learn. The Met Office issues four forecasts a day for 31 sea areas, each covering 24 hours. BBC Radio 4 broadcasts selected issues.
Warnings first
The bulletin opens with the gale warnings in force and the areas they cover. If your area is named, read that warning before anything else. Warnings are also broadcast separately, as soon as they are issued.
General synopsis
The general synopsis summarises pressure systems and their expected changes. Example: "Low, Biscay, 996, moving steadily northeast, expected Plymouth 1000 by 0600 tomorrow." The low is over Biscay with a central pressure of 996 hectopascals (hPa), a pressure unit. It is forecast to move northeast to Plymouth, with its pressure rising to 1000 hPa by 0600 UTC tomorrow. Here, 1000 is a pressure; 0600 is a time.
Area forecasts
In the UK shipping forecast, each sea area gets a short forecast in this order: wind direction and force, sea state, weather, visibility. Example: "Southwest 5 to 7, veering west later. Moderate or rough. Rain then showers. Moderate or good, occasionally poor." Because this order is fixed, labels are left out. Write it down as you listen. Other products may use a different order or give swell separately.
From bulletin to decision
A forecast is only useful once you decide something. Compare it with your boat, your crew and the worst part of the route, such as a headland or an exposed crossing. Plan for the upper figure: in "5 to 7", expect 7 at times. Deciding whether to go has its own practice unit in this module.
2Key data
- WMO high seas bulletin order
- Warnings → general synopsis → area forecasts
- UK area forecast order
- Wind → sea state → weather → visibility
- UK shipping forecast
- 31 sea areas, issued 4 times a day, each valid 24 h
- Synopsis gives
- System, position, pressure (hPa), movement, expected change
- "5 to 7"
- Wind in that range; plan for force 7 at times
3Key points
- 1
WMO high seas bulletins run: warnings, general synopsis, forecasts.
- 2
UK shipping forecast area order: wind, sea state, weather, visibility.
- 3
The synopsis gives each system’s position, pressure, movement and expected change.
- 4
Write the forecast down as you listen; read your area's warning first.
- 5
Plan for the upper end of any range.
4Frequent mistakes
Wrong: Skip the synopsis and listen only to your own area.
Right: The synopsis explains why the weather will change and when. It helps you judge if the timing could be early or late.
Wrong: "Southwest 5 to 7" means about force 6 all day.
Right: The wind will be anywhere in that range. Plan for force 7 at times, and stronger gusts.
Wrong: A gale warning for the next sea area does not affect you.
Right: Weather systems move. Check where the low is going: the next area's gale may reach you.
5Practice case & exam keys
You hear: "Low, Fitzroy, 988, moving rapidly northeast, expected Fastnet 984 by midnight. Plymouth: Southwest 6 to gale 8, veering west 7 later. Rough or very rough. Rain then squally showers. Moderate, occasionally poor." Your crew says the low is weakening and plans for force 6. Correct the briefing.
Show the answer
The low is forecast to move from Fitzroy to Fastnet and deepen from 988 to 984 hPa, moving northeast at 35–45 knots. Plymouth’s mean wind is southwest force 6–8, later veering west force 7. Plan for force 8 and stronger gusts. Significant wave height is 2.5–6 m; individual waves can be higher. Rain gives way to squally showers. Visibility is 2–5 nm, occasionally 1,000 m to 2 nm.
Exam keys
- WMO high seas bulletin layout: warnings, general synopsis, forecasts.
- UK shipping forecast area order: wind, sea state, weather, visibility.
- The synopsis gives each system's position, central pressure, movement and change.
Finish this unit
When you've read it, match the terms, then answer three questions. Get them all right to finish the unit; opening the page alone doesn't count.
My notes for this unit
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