Layers

Layer order

The top row is drawn on top. Use the arrows to move a layer up or down, the tick box to show or hide it, and tap its name to open its settings below. Hillshading always sits right above the base map, since it darkens the map itself.

Angle classes

The cogwheel on a class limits it to the directions a slope faces and an altitude range. Where classes overlap, the first one that matches colours the ground, so you can give the same angles different colours by direction. Ground under 3° counts as every direction.

Official steepness

Norway: NVE release areas above 27° plus modelled runout, the layer Varsom and regObs use. © NVE, NLOD.

Avalanche runout (alpha)

How far avalanches from the slopes above can run, in three bands built the way NVE builds the runout on Varsom's steepness map. Start zones are slopes from about 28° that are sheltered from the wind (ridges must be steeper), and snow runs downhill until the line back up to its start zone is flatter than the band's angle. In mapped avalanche paths the median avalanche stops before 32°, one in four runs past 27° and one in twenty past 23°. Those numbers come from avalanche paths and are dominated by large natural avalanches, so they say how far snow can go, not whether a slope will release today. Start zones in dense forest are left out, using Copernicus tree cover from 2018 (Europe only), but the runout still runs through forest: a big avalanche breaks trees, and thin or felled forest can still release. Unlike NVE's map it also colours the steep ground the snow starts on and runs through. The colours are NVE's, so in Norway switch one of the two layers off to compare them. Computed in your browser from coarse elevation tiles: an indication of where runout is plausible, not a hazard map.

Sun exposure

How much direct sun each spot gets on the chosen day, including shadows cast by the terrain around it, counted in hours of full sun: an hour of sun hitting the ground square on counts as an hour, sun at a glancing angle for less, because that is what warms the snow. Blue gets little or none; orange about as much as the best-placed slope can get that day. Sun lower than 5° over the slope is not counted. Tap the map for the plain hours in sun as well. Shaded slopes tend to keep cold, soft snow; sunny ones warm up during the day, which in spring means wet snow and loose slides by midday and a crust once they freeze again. Times are in your device's time zone. It is computed from the same coarse elevation tiles as the slope colours, sees only about one tile's width of terrain towards the sun, so the shadow of a mountain further away is missed, and knows nothing about cloud.

Wind exposure

Looks upwind from every spot for about 300 m. Where the terrain there rises above the spot, it is in the lee and drifting snow is likely to have been dropped; where the ground falls away towards the wind (ridges, crests, windward slopes), snow is likely blown off and hard or bare. The direction is the Open-Meteo weather model's wind over the last three days at the map centre, counting only hours strong enough to move snow, or one you set on the dial. Valleys steer the wind locally, and the model knows nothing about that.

Pink is where wind slabs form. Soft, wind-deposited snow there can be the most dangerous snow on the mountain. This is a terrain model, not an observation; read the avalanche forecast for wind slab problems.

Snow condition

"Follow the map" shows seNorge snow depth in Norway and the daily MODIS photo everywhere else. seNorge is NVE's snow model on a 1 km grid, run from measured precipitation and temperature; it knows nothing about wind, so ridges are barer and lee slopes deeper than it says. The daily satellite photos are coarse but new every day: snow and cloud are both white, so step back a day or two with the arrows until you find a clear pass. The MODIS snow cover layer tells snow from cloud for you and leaves cloud blank. Sentinel-2 cloudless is sharp but built from mostly summer scenes of a whole year, so it shows glaciers and rock, not this week's snowline; for a sharp picture of a given date use the Copernicus link or paste a Sentinel Hub tile URL with {date} in it.

Avalanche forecast

Norway comes straight from the Varsom API; the Alps and the rest of Europe from the shared EAWS data behind avalanches.org, drawn on the official forecast regions. Each region is coloured by the highest level the service gives it that day, at any elevation. Tap the map to see which region you are in, the split between high and low elevations where there is one, and a link to the full forecast. A regional level says nothing about the slope you are looking at, and the avalanche problems, aspects and elevations in the text matter more than the number.

Heatmap

Ski pistes

Pistes, ski routes and lifts from OpenStreetMap, drawn by OpenSnowMap. Tick it in the layer order list to show it. Anyone can edit OpenStreetMap, so lines can be missing or out of date, and a marked ski route off piste says nothing about whether it is safe today.

Huts

DNT cabins, other mountain huts and open wilderness huts in Norway and the Alps, from OpenStreetMap. Tick it in the layer order list to show it, and tap a hut for its details. Many staffed huts are only staffed at Easter and in summer, and DNT huts need the DNT key, so check with the owner before you rely on a hut for the night.

GPX track

Show a track, route or waypoints from a GPX file, for example last season's trip or a route someone shared. The file is read on your device and not uploaded anywhere. Someone else's line was right for their day, their snow and their group, not necessarily for yours.

Hillshading

Shades slopes that face away from the light, drawn from the same elevation data as the slope colours. Tap or drag the small dial to set where the light comes from; northwest gives the clearest relief, while the real sun direction (south around midday in winter) shows roughly which slopes stay in shade. Each slope is shaded on its own, so shadows cast by neighbouring mountains are not shown. The slider sets how dark the shading gets.

Base map

Kartverket only covers Norway, so "follow the map" swaps to OpenTopoMap once you leave it. The national maps and aerial photos for Switzerland, France and Austria only cover their own country and are blank or coarse outside it, so you pick those by hand. Aerial photos are taken in summer, which makes them good for reading rock, forest and gullies, not snow. The grey Kartverket map lets the slope colours stand out.

The corner shows a scale bar and, when the base map draws named contours, its published interval for the zoom you are at: 20 m on Kartverket topo, 10 m on OpenTopoMap from zoom 15 and coarser below. Raster tiles carry no metadata, so this is the map series' equidistance, not something read out of the tile, and it can differ locally. The ruler button measures straight legs between the points you tap, and reads ascent and descent off the same coarse elevation tiles the slope colours use — expect it to smooth away small rolls and to run short on a line drawn with few points.

While measuring, the curve at the bottom shows the elevation along the line, coloured by how steep the ground under it is; drag along it to find the spot on the map. The menu above the curve switches between the fixed avalanche colours and your own slope classes; with your classes, direction and altitude filters count just as on the map (marked * in the key), and edits show up when you press Redraw map. "Steepest ground" is the slope of the terrain the line crosses, which is what matters for avalanches, and a dot marks its steepest spot on the map. "Steepest track" is how steeply the line itself climbs or drops, averaged over about 60 m, in the direction you drew it — a comfortable skin track is usually 10–15°. Both come from the same coarse elevation tiles, so short steep steps can hide between the samples.

The time is Werner Munter's rule: one unit per kilometre and one per 100 m of ascent or descent, divided by 4 units an hour going up, 6 on the flat, and 10 skiing down (6 walking down). It leaves out breaks, transitions and trail breaking, so calibrate it against your own tours. The % box to its left scales it to your own pace: at 70% you move at 70% of Munter's speed, so the time, and every arrival time worked out from it, gets longer. Save GPX writes the line with elevations as a track that watches and phone apps import as a course.

From the start time you give, the same Munter time says when you reach each point of the line. The measure box then says how much of the way is in sun as you pass, on the date set under Sun exposure, and which spot has had the most sun before you get there, the one most likely to be soft or wet. The first strip under the curve is sun (yellow) or shade (blue) at the time you pass. With Wind exposure on, the second strip shows lee (pink) and exposed (teal) ground, and stretches over 30° in the lee are edged pink on the map: that is classic wind slab terrain. It is only as good as the Munter estimate of your pace and the coarse terrain models behind it.

Slope is computed in your browser from open 10–30 m elevation tiles, so it is coarser than Kartverket's 1 m laser data. Treat the low classes as indicative and verify steep terrain against the official layer for the country you are in.

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