How do I know if a storm is coming?

24 June 2016

1. Weather Forecasts

Nowadays, perhaps the most reliable way to predict a storm is to make sure you have regular access to an up-to-date weather forecast. In the UK, the Coastguard issue forecasts every 3 hours including less frequent shipping forecasts for the entire coastline and surrounding sea areas. The shipping forecast is also broadcast on BBC radio 4 LW AND FM at specific times of the day and night. The forecasts for inshore and shipping forecasts are detailed in the Almanac. Make sure you make particular note of the time the forecast was issued as well as when it was broadcast!

2. Passage Planning

If you are passage planning, the most convenient way to check for weather is to refer to specific websites that offer fairly reliable weather models based on GFS and/or NWP data sets. Some sites worth visiting include;

The Met office also offer weather for sailors and for the time being it is their forecast that is broadcast on the BBC and inshore by the Coastguard.

Bespoke forecasts from a real live forecaster are available for a small fee from sources such as:

3. The barometer

The trusty barometer is a great way to tell if a storm is coming. If your barometer is falling or rising at more than 10mb over a three hour period expect storm force winds! If it is falling or rising more than 4mb per hour expect winds up to Gale Force 8 as a minimum. An accurate barometer and a religiously kept log of its readings is something to be relied upon. A rapidly falling (or rising) barometer indicates gale force+ winds are on the way.

How to Use a Barometer when Sailing

4. The sky and the sea

Keeping an eye on the sea state and the clouds above is a good way to tell what is on the way. A larger swell usually precedes a storm or gale and is evidence of big weather to follow. Likewise, ‘mares tales’ or ‘mackerel skies’ streaming across the sky at high level are a good indicator that a change in weather is due in the next 36 hours. Basically, flat clouds getting lower or ‘puffy’ clouds bubbling higher (the latter being the creation of a thunderstorm) are likely to evidence bad weather is on the way.

A circle around the moon usually indicates wet weather is on the way and a red sky in the West at night usually indicates a High Pressure system with dry air is on the way to you from the West.

For more information on weather in the northern and southern hemisphere click on the links below;

RYA Weather for the Northern Hemisphere

RYA Weather for the Southern Hemisphere

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