Timing words and when to check
1The lesson in plain words
In UK marine forecasts, timing words count from the issue time. Check the valid period and time basis, then check for updates before leaving and at sea.
Issue time and valid time
The issue time tells you when a forecast was issued. Its valid period tells you which hours it covers. UK shipping forecasts use UTC, Coordinated Universal Time. Always check the time basis printed on your product. Mainland Spain and metropolitan France use UTC+1 in winter and UTC+2 in summer; the Canary Islands are one hour behind mainland Spain.
Imminent, soon, later
In UK marine forecasts, these terms count from the issue time. Imminent: within 6 hours. Soon: 6 to 12 hours. Later: more than 12 hours. If a gale was "soon" in a warning issued at 0500 UTC and you read it at 1100 UTC, it may arrive at any time now.
How fast systems move
UK forecasts describe how fast a low- or high-pressure system moves. Slowly: under 15 knots. Steadily: 15–25 knots. Rather quickly: 25–35 knots. Rapidly: 35–45 knots. Very rapidly: over 45 knots. These speeds describe the system’s movement, not its wind speed.
When to check
Look at the outlook a few days ahead to choose your day. Read the full forecast the evening before and again just before you leave. At sea, listen to every new broadcast and warning. Write the main points in the log. A new forecast replaces the old one.
2Step by step
Checking the weather for a day sail
- 1
Two or three days before, read the outlook and look at the pressure chart.
It shows whether a front or strong wind is likely and helps you pick the day.
- 2
The evening before, read the official forecast and warnings for every area on the route.
You can still change the plan or the departure time without pressure.
- 3
Before leaving, read the latest issue. Note its issue time, time basis and valid period.
Timing words count from the issue time. Check that the valid period covers your passage, and convert times if needed.
- 4
Compare it with what you see: wind, sky, sea and the barometer.
If reality is worse than the forecast, the forecast may be late or wrong.
- 5
At sea, listen to each VHF broadcast or check NAVTEX and log the key points.
Warnings can be issued at any time; you need them before conditions arrive.
3Key data
- Imminent
- Within 6 hours of issue
- Soon
- 6 to 12 hours after issue
- Later
- More than 12 hours after issue
- System moving slowly / steadily
- Under 15 knots / 15–25 knots
- Rapidly / very rapidly
- 35–45 knots / over 45 knots
- Mainland Spain and metropolitan France
- UTC+1 in winter, UTC+2 in summer
4Key points
- 1
UK timing words count from the issue time, not from when you read them.
- 2
In UK forecasts: imminent within 6 h, soon 6–12 h, later over 12 h.
- 3
UK shipping forecasts use UTC. Check your product’s time basis and convert to local time.
- 4
Check days ahead, the evening before, before leaving and at sea.
- 5
A newer forecast replaces the old one; log the key points.
5Frequent mistakes
Wrong: "Soon" means within the next hour.
Right: In a UK marine warning, "soon" means 6 to 12 hours after the issue time. Check when the warning was issued.
Wrong: The forecast I read yesterday is still good for today.
Right: Forecasts are updated several times a day. Read the latest issue before you leave.
Wrong: Forecast times are in local time.
Right: UK shipping forecasts use UTC. Check the time basis printed on your product. Mainland Spain uses UTC+2 in summer; the Canary Islands are one hour behind.
6Practice case & exam keys
A UK gale warning issued at 0600 UTC says: "Southwest gale force 8 soon." You read it at 1000 local time in mainland Spain in July. A friend counts six more hours from when you read it. What is the forecast window, and why is your friend wrong?
Show the answer
In July, mainland Spain is UTC+2, so 1000 local is 0800 UTC: the warning is 2 hours old. "Soon" means 6–12 hours after issue, from 1200 to 1800 UTC, or 1400 to 2000 local time. Your friend is wrong because the hours count from 0600 UTC, not from when you read it. That is the forecast window, not an exact arrival time; check for updated warnings.
Exam keys
- UK forecasts: imminent within 6 h; soon 6–12 h; later more than 12 h, all from issue time.
- UK shipping forecasts use UTC; check the time basis, issue time and valid period of your product.
- Check the forecast before planning, before departure and at each broadcast at sea.
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.
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