Mountain safety
Mountain weather conditions
No matter from which direction the air comes, if it meets a range
of hills it will have to do one of two things: either find a way through
the valleys or be forced over the top. When air is forced to rise, it
always cools. The rate of cooling is not constant, but on average temperature
drops by around 2 °C per 300 m (1,000 ft) of ascent. This means
that at the summit, the temperature will be much cooler than in the
valley. Couple this with the average doubling in wind speed at 900 m
compared to low ground, and the overall wind-chill effect on a wet or
perspiring human body can be very large indeed. A wind of 40 m.p.h.
and an air temperature of 3 °C, not at all an uncommon combination
even in summer, will yield a wind-chill temperature of -10 °C.
Mountain ranges produce a number of potentially
hazardous weather phenomena
- Gales, storm-force winds, persistent heavy rain or blizzards
can be raging at the top, when it is merely cloudy in the valleys.
- Ice and snow can last long into spring or summer, especially
on the sun-shielded north-facing slopes.
- Certain conditions can also give rise to avalanches.
- Low cloud is usually more frequent and extensive on the windward
slopes, giving widespread hill fog, although under some situations
the lee slope can also be affected by hill fog.
|
However, on a day-to-day basis, such potentially dangerous weather is
the exception rather than the rule. Checking the mountain
forecast gives essential forewarning of the likely conditions on your
chosen route.
Rescue services
Whenever an incident occurs requiring the mobilisation of a Mountain
Rescue Team, the Met Office is ready, 24 hours a day, seven days a week,
to provide back-up. The forecasters at RAF Kinloss support the mission
planning and control at the Aeronautical Rescue Co-ordination Centre,
and the forecasters at RAF Lossiemouth provide forecasts directly to the
helicopter crews.
Supporting the Scottish Avalanche Information Service (SAIS)
 |
Forecast data supplied by the Met Office contribute to the preparation
of the avalanche forecasts produced by the dedicated team at Glenmore
Lodge.
The Met Office provides a daily forecast service to SAIS from
mid-December to shortly after Easter. This forecast is transmitted
to each of the five sites at Northern Cairngorm, Southern Cairngorm,
Lochaber, Glencoe and Creag Meagaidh for input into their avalanche-prediction
computer models. Content is for summit level at each site and contains
details of precipitation, temperature, wind, and the freezing levels
of the air and wet-bulb temperatures. In addition, direct communications
access is provided to high-level automatic weather stations for
automatic ingestion into the prediction models. These high-level
automatic weather stations have been installed by the Met Office
at Cairnwell, Cairngorm, Aonach Mor and Bealach Na Ba, helping to
improve the accuracy of the mountain forecasts.
|
|
