How to read the weather

  • by David Alcock
How to read the weather

There are many reasons the British Forces are at the top of their game and one of the factors that created hardened, robust soldiers is the weather they train in. From the Scottish mountains to the Brecon Beacons, the weather can change from sun to torrential downpours in a matter of minutes.

We know rain... living in Scotland it's just part of life and we have to just get on with it. Having the right clothing, understanding weather forecasts and being prepared are essential for being safe and for tabbing from A to B as fast as possible.  Most of the time, the weather and all it can throw at you doesn't stop you getting out... things carry on and you have to just deal with it. 

The Met Office weather forecasts for the UK constantly and being able to read the charts and understand the forecast are really important and we advise you get to know at least the basics. Different air masses affect the UK bringing a variety of weather and the UK experiences a wide range of weather hazards throughout the year. These include rain, wind, snow and drought.  


Reading Weather forecast charts

When looking at weather charts, you’ll see some of the following features that will help you with basic weather forecasting before heading out in the the hills. 

The plain lines that curve across the map are called isobars (iso = equal, bar = pressure). They join together places with the same mean sea level air pressure (weight per square area of air above). Some have numbers on them showing this value in hectoPascals.

Here are four wind tips:
 Winds blow almost directly (but not quite) along the isobars.
In the Northern Hemisphere, the flow is ANTI-CLOCKWISE around LOWS and CLOCKWISE around HIGHS
2. The closer the isobars, the stronger the winds.
3. Because of the 'spin-out' effect when turning corners, the wind speed can be:
• Up to 20% higher than the isobar spacing would suggest as the air turns around (and out of) a High
• As much as 20-40% lighter than the isobar spacing would suggest as the air turns around (and into) a Low.
4. Isobars are only approximations and only tell about the general wind flow, not the details.

An air flow originating from a prescribed location is called an air-mass. Air-masses are named according to where they have come from and each has its own characteristic temperature and humidity.

• A tropical air-mass consists of air flowing from the tropics (WARM)
• A polar air-mass consists of air flowing from polar regions (COLD)
• A maritime air-mass is one flowing over a large sea area (MOIST)
• AA continental air-mass is one flowing over a large land area (DRY)

Heading out, check out the weather links below

Mountain Weather Information Service
A dedicated team of professional meteorologists with experience in mountaineering produce forecasts for 10 UK mountain areas 365 days a year.

Below is the current weather pattern for the UK.
 Check out for more features



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