Climate of the Rocky Mountains

Few journalists have been subjected to more jokes and ridicule than the weather reporter, and rarely is this vocation more futile than in the Canadian Rockies. In the high county, rugged landscapes and high winds interact to make the prediction of weather a black art. A sunny July day can suddenly deteriorate into a violent thunderstorm leaving a dusting of fresh snow to outline the summits. Just as quickly, the storm may clear and the day return to its previous peacefulness. On the other end of the spectrum, cold arctic systems may be interrupted by the welcome warmth of the famed Chinook wind. Suddenly, the mercury climbs as warm western winds bring a welcome respite from winter.

Along with freak weather systems and rapid change, the mountains are influenced by both regional and local conditions. While the prevailing winds may blow from the west, mountain valleys act as a wind funnel, providing locally divergent wind patterns. The lofty heights of the mountains may also influence the weather allowing clouds to form around a summit while the remainder of the sky remains clear. Anyone who has spent time in the Rockies has found themselves the victim of a sudden storm, perhaps appearing suddenly as they crest a summit ridge and find themselves in the path of an approaching squall.

To predict the weather in the mountains is difficult at the best of times. For most, it is sufficient to recognize typical patterns to help maximize enjoyment and safety when playing in the Rockies.

Predicting the Weather

In the Rockies, predicting the weather is a hit and miss process. Even the best weather reporters hit the bulls-eye only rarely. Since the temperature can vary by more than 40°C in less than an hour, how does one go about predicting the weather? The simplest answer is that they don’t. The best solution is to assume that the weather will take a change for the worst. Veteran mountain hikers don’t even walk to the corner store without an extra layer or two safely stuffed into a day pack. This is especially critical as you head into the backcountry. The weather will change, so prepare for it.

Once on the trail, take note of significant changes in wind direction, temperature and cloud formations. With the increasing popularity of altimetres, most of which work using barometric pressure, you can get an indication of changes by the fact that your elevations will suddenly begin to change far more rapidly than the trail. Dropping barometric pressure often means a change for the worst. If suddenly the winds pick up, towering cumulus clouds begin to build vertically, and the bases begin to darken, take this as a hint that it may be a good time to move off of exposed ridgetops and summits. Typically on a hot day, water vapour condenses around mountain tops,  forming dark clouds which have the potential culminate in short lived intense electrical storms. Remember, you may not know that a storm is coming until it crests the summit towards which you may be ascending.

All Material © Ward Cameron 2005