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How does the wind affect an avalanche situation?

In this explanatory article you will find out more about the wind as a significant factor in creating potentially dangerous avalanche terrain.

There is also Flash animation that supports the text. If you don't have a Flash player download it here.

What is the wind and what creates it?

In sake of simplicity we can say that the wind is moving air. We cannot see it nor touch it but we can definitely observe and feel its effects.

Wind is created by many elements but the most important one is temperature. Quickly changing temperatures cool or warm the air. Then the hot air travels up and the cold air goes down (as in your living room) which makes for a circulation of the air and creates the wind.

Is wind good or bad?

There is no answer to that. On a foggy and cloudy day high winds may bring clear skies and vice versa. In terms of backcountry safety wind is another factor, of many others, to consider when backcountry skiing or glacier traveling. It can play in your favor or against. Now you can decide...

So, how can the wind create for potential avalanche terrain?

At this point lets watch the animation of what happens in the backcountry with the snow when the wind is present. (If you don't see animation below this sentence you need to download Flash player.)

Next few points describe and explain the animation:

1. The wind affects the snow pack the most greatly when there is a new snow after a snow fall or when the snow on the surface (top layers) isn't tied to the below (already tied) layers yet.


2. It is enough that the wind has speed as little as 5 metres per second (18km/h) in order to cary significant amounts of snow and to move it around.


3. Blowing snow is then moved from a slope that faces the wind (windward slope) over the ridge to the slope that faces the downwind (leeward slope).


4. Then the snow is accumulating on this leeward slope, mostly just few metres below the ridges, thus creating something like a snow pillows. These pillows can form massive unstable pockets of wind blown snow.


5. Snow pillows can trigger avalanches themselves because of the overload (more snow then the actual slope can cary under given conditions) they are creating. Also, such unstable areas of snow can be disturbed by a skier or snowmobiler thus triggering an avalanche.


6. As you saw in the animation it is safer to travel on or under the windward slopes than on leeward slopes if you suspect that such conditions were created before or while on the trip.

Now, it is a good time to watch the animation once more.

OK, but what can I do for my safety?

• It is always good to check also the wind conditions when checking an avalanche bulletin or advisory. Look for directions/orientation and speeds of the wind.


• Example:
  If a forecast calls for north winds that means the wind will be blowing from the north not to the north. It will be blowing from north to south.


• Cary a map while on the trip. Because if you know the directions/orientation of the wind with a map you can easily find out which sides of any mountain are windward and leeward slopes.


• Example:
  If there were north winds blowing new snow then the north slopes can be marked as windward (safer ones) and the south slopes as leeward (more dangerous ones).


• Observe mountain ridges - you will be able to see from where the wind was blowing and to where the blowing snow was packed.


• Remember:
  The directions of the wind over the high ridges can be quite different from those in the valleys. Therefore also watch out for wind blown pockets of snow on the sides of the gullies.


• Watch also for an amount of snow fall in relation to the winds. Generally, the wind doesn't affect the snow pack significantly in the spring months because the snow was already settled by warm temperatures. High amount of new snow are unlikely in the spring months as well.


• Remember:
  Windy conditions that affect the snow pack happen all the time thus make sure you are considering also the wind as a factor when backcountry skiing.

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