Wind – the most significant influence on mountain weather.
Both speed and direction are the first contributing factors I look for when reading a forecast and thus making my plan. Wind speeds above a certain velocity make mountaineering unbearable and contribute to most, if not all, incidents contributing to mountain weather. It is the most prominent and often memorable feature of the UK’s mountains and is associated with changing patterns in high and low air pressure. The strongest winds are experienced with the deepest and most turbulent depressions and consequently happen during winter.
How high is too much?
Wind speeds above 35mph are worth consideration, and nearly all mountain journeys, especially during winter, will be adjusted for speeds above 50mph. I weigh around 67kg, and a 60mph wind will feel powerful and significantly impact my walking gait and stability on paths, never mind exposed ridges and summits. Working in the mountains does mean I head out into the hills during storm-force winds, but careful route planning is essential for a successful and safe day in high winds.
Some critical (wind*) considerations for a day of winter climbing in Scotland are below:
- Has it snowed, and what level is the snow cover – if it snowed overnight, the approach could be slow and tiring.
- What has been the prevailing wind direction over the previous five days – snow distribution and cross-loading of slopes is a hazard following a change of wind direction.
- What aspect is the climb facing – avalanche avoidance!
- Who are my climbing partners – are they as fit or lighter than me?
- How do I get back down – 95% of incidents happen in the final 5% of your day.
- What is the maximum elevation of my day – most forecasts focus on wind speeds at max height; can I climb lower down?
- Are there rivers to cross – nobody wants to get wet crossing a river! Strong winds make for unstable people.
This list can be extensive and will cross over into other considerations discussed below. However, sticking to these seven points around wind will help you make good decisions and avoid unwanted eventful days in the mountains.