How to read steepness and the direction a slope faces, and how that fits with the official avalanche bulletin. Traverse does not make avalanche forecasts.
Slope angle and aspect describe the ground. They do not say whether a slope will slide today. Read the official bulletin, look at the snow, and make your own decision. If someone is caught in an avalanche, call 112.
Five steps, in this order
Read the bulletin firstThe official bulletin gives the danger level, the avalanche problem, and which aspects and elevations it applies to. Traverse does not make forecasts, so this part always comes from the bulletin and your own observations.
Find the problem slopes on the mapIf the bulletin names north-facing slopes above 2,200 m, use the aspect and slope layers to see which parts of your route are on those slopes and how steep they are.
Check steepnessMost slab avalanches release on slopes between about 30° and 45°. Slopes under about 27° rarely slide as a slab, though they can still be in the path of one from above.
Look above and belowAvalanches run downhill. A flat valley floor under a steep face is in the runout, and a gentle slope with a steep one above it can be hit. Check what is above, not only what you stand on.
Decide with the snow in front of youThe map shows terrain. Snow and weather on the day decide whether a slope is a problem. If you are unsure, choose less steep ground, or turn around.
Slope angle
Steepness is the first thing the map can tell you. Traverse colours slopes from 27° to above 45°, in the bands used by avalanche education. The slope angle map guide explains each band and what the data cannot show.
Aspect
Aspect is the direction a slope faces. A bulletin that says “problem on north-west to north-east slopes above 2,000 m” is giving you an aspect and an elevation. On the Traverse web map, switch on the Aspect layer to see which way each steep slope faces, or use the Slope here tool: tap a spot and read its steepness and facing.
The sun tool adds a second view: pick a date and a time and see which slopes face the sun. It shows the slope’s own direction only, not shadows from other mountains, trees or cloud.
Where there is no bulletin
Some places, including Kosovo and Albania, have no public bulletin. Then slope, aspect and the snow itself are all you have, and going with a local guide is the sensible way to learn an area. Read the ski touring guide for Kosovo and Albania.
Aspect is the compass direction a slope faces: the direction water would run downhill. A slope facing north has a north aspect. Bulletins often name aspects and elevations where the problem is worst.
Why does aspect matter for avalanches?
Aspect changes how much sun and wind a slope gets. In the Northern Hemisphere, shaded slopes facing roughly north keep cold snow, and weak layers within it, for longer. Sunny slopes warm up, which can make wet-snow avalanches more likely in spring or on a warm day. Wind loads snow onto the sheltered side of a ridge.
What slope angle is avalanche terrain?
Most slab avalanches release on slopes between about 30° and 45°, with the most releases around 35° to 40°. Traverse’s slope layer starts at 27° to allow for the smoothing in elevation data.
Does Traverse show the avalanche forecast?
No. Traverse does not produce avalanche forecasts or danger levels. Use the official bulletin for your area, and the slope and aspect layers to understand the terrain it describes.
Is there a bulletin for Kosovo and Albania?
At the time of writing there is no public avalanche bulletin for Kosovo, Albania or Montenegro. In an area with no bulletin you have to assess snowpack, weather and terrain yourself, or go with a local mountain guide. Our ski touring guide has more.
What is the Avalanche Terrain Exposure Scale?
ATES is a way of classifying terrain as simple, challenging or complex by how much avalanche terrain it contains and how it is connected. Traverse’s route terrain rating uses the same three words and is worked out automatically from slope, so it is not an official ATES classification of a route.
How accurate are the slope and aspect layers?
They come from an elevation model of about 30 m cells. That shows the shape of the ground well but smooths small features: short cliff bands, gullies and cornices can be steeper than shown. Look at the slope itself when you get there.
Where do the layers work?
Kosovo, Albania and the Sharr range today. The 3D map works worldwide without them.