1 // Look up to the sky
Make an effort to look at the sky, and ideally a barometer, as often as possible. Although the clouds and wind aren’t perfect for predicting coming weather, they do provide important clues. Cumulonimbus clouds, for example, may indicate heavy showers or even thunderstorms. If you have a barometer, note how pressure changes. In general, an increase indicates better weather; a decrease suggests conditions will deteriorate.
2 // Watch out for depressions
The main changes in weather come with depressions (‘lows’) that move in from the west. Where different types of air arrive there are specific ‘fronts’ with different clouds and associated weather. Warm fronts may bring long periods of rain, whereas on cold fronts the changes are usually more rapid and extreme; other types of front may give hours or even days of rain.
3 // keep an eye on what the wind is doing
Because of friction, winds at the surface — those that we feel — are not as strong, nor in exactly the same direction as those shown by most clouds. When the highest winds (jet-stream winds and clouds) are blowing in a very different direction to that shown by lower clouds, change is on its way.
4 // Read different types of cloud
There are specific, easily-seen features that mark the different types of clouds and the associated weather. The highest clouds (‘jet-stream cirrus’) provide an important indicator of forthcoming changes in the weather, and show when winds are ‘crossed’. Along with different cloud types, learning how to recognise crossed winds will help you predict weather changes.
5 // Find the best forecast charts
Unfortunately, most TV weather forecasts don’t show the all-important isobars, indicating wind direction and speeds. Good examples are the charts provided by the UK Met Office. The isobars will provide significant information about how the weather may change. metoffice.gov.uk/public/weather/surface-pressure
6 // Spot progressive changes in cloud formations
There’s a definite sequence of changes in cloud types as a depression approaches and brings changes in the weather. The changes in the clouds are often clear to see and depend on where the centre of the low will pass — to the north or south, for example — with different changes to the weather. The sequence of different cloud types — cirrus, cirrostratus, altostratus and nimbostratus — is highly characteristic of an approaching depression and poor weather.
7 // Learn when thundery weather may be on the way
The conditions under which severe thunderstorms arise are different from the changes associated with depressions. When hot, humid air arrives from the south, or when it’s been very hot and sunny, there will be a growth of large cumulonimbus clouds — watch out for these and realise the danger of lightning, and know how to shelter.
Published in the May 2018 issue of National Geographic Traveller (UK)