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Danger and Warning Signs

16.07.2025

Emergencies and accidents rarely happen out of the blue without any warning. Of course, sometimes you can be unlucky and simply be in the wrong place at the wrong time. But when it comes to avalanche danger, the weather forecast and group dynamics, there are almost always warning signs that need to be recognized and evaluated in order to make the right decisions.

Arrow Down White

This article is about:

01

Danger signs

Danger signs are indications of existing dangers. They can confirm an expected or predicted danger or indicate dangers that were not anticipated. They are therefore important for confirming or invalidating planning assumptions in the field – or for drawing attention to other, unforeseen dangers. This verification and scanning of conditions must be carried out on an ongoing basis and must also be reflected in decisions and actions.

"Danger signs are the reality check of forecasts & planning!"

Walter Würtl

Danger sign “new snow”

The fresh snow slabs (alarm signs) match the existing drift snow packs and wind signs (danger signs). The frost build up riming (danger sign) on the rope of the material ropeway is just as recognizable as the numerous protruding or barely covered stones (danger sign).

20 cm of fresh snow has fallen on a stable layer of old snow without wind and without forming a thin layer. Therefore, there are no danger or alarm signs, but the weather is better than reported with perfect visibility. All in all, it's a perfect day for freeriding. Enjoy! © snow institute I argonaut.pro
20 cm of fresh snow has fallen on a stable layer of old snow without wind and without forming a thin layer. Therefore, there are no danger or alarm signs, but the weather is better than reported with perfect visibility. All in all, it's a perfect day for freeriding. Enjoy! © snow institute I argonaut.pro
A ‘fresh snow problem’ only refers to the risk of avalanches. If you are travelling during snowfall, there are often other dangers to consider: more difficult route finding, more difficult orientation and communication due to limited visibility, risk of suffocation/injury in the event of unfavourable falls/getting stuck on trees/shrubs and possibly the risk of branches/trees in the forest breaking due to the weight of the fresh snow (snow breakage). Furthermore, the more complex/impossible rescue measures (no flying weather) must be taken into account. © snow institute I argonaut.pro
A ‘fresh snow problem’ only refers to the risk of avalanches. If you are travelling during snowfall, there are often other dangers to consider: more difficult route finding, more difficult orientation and communication due to limited visibility, risk of suffocation/injury in the event of unfavourable falls/getting stuck on trees/shrubs and possibly the risk of branches/trees in the forest breaking due to the weight of the fresh snow (snow breakage). Furthermore, the more complex/impossible rescue measures (no flying weather) must be taken into account. © snow institute I argonaut.pro
Following existing tracks is a tempting but bad idea, especially in fresh snow and poor visibility. If you don't know the terrain and the route, it's better to stay in your own familiar comfort zone in such conditions. © snow institute I argonaut.pro
Following existing tracks is a tempting but bad idea, especially in fresh snow and poor visibility. If you don't know the terrain and the route, it's better to stay in your own familiar comfort zone in such conditions. © snow institute I argonaut.pro
20 cm of fresh snow has fallen on a stable layer of old snow without wind and without forming a thin layer. Therefore, there are no danger or alarm signs, but the weather is better than reported with perfect visibility. All in all, it's a perfect day for freeriding. Enjoy! © snow institute I argonaut.pro
20 cm of fresh snow has fallen on a stable layer of old snow without wind and without forming a thin layer. Therefore, there are no danger or alarm signs, but the weather is better than reported with perfect visibility. All in all, it's a perfect day for freeriding. Enjoy! © snow institute I argonaut.pro

Danger sign “wind slab”

From approx. 15 km/h (“weak wind”), snow is transported as it falls or afterwards and deposited as drift snow on the leeward slopes. The “slab” created by drifting snow is a prerequisite for a dry slab avalanche (together with a weak layer over a large area, a slope steepness of over 30 degrees and an additional load). Danger signs for drifting snow are recognizable on the snow surface in various forms. Some signs are acute (drifting snow, snow plumes), most must be evaluated in terms of their significance (snow dunes, snow dangles/sastrugi, potholes, comet tails). A few usually indicate the main wind direction over a longer period of time (cornices, frost build up riming).

Many of these danger signs of the wind slab problem disappear when fresh snow falls over them without the influence of wind – which does not mean that they are no longer dangerous!

The following gallery shows various hazard signs relating to the “drift snow problem”. As the aim is to identify fresh drift snow packs – i.e. to determine whether the transported snow is currently still dangerous – the pure wind signs are dealt with in a separate section below. Just because wind signs are present does not mean that the drifting snow is fresh and dangerous.

© snow institute I argonaut.pro
© snow institute I argonaut.pro

Danger sign “persistent weak layer”

A fresh slab avalanche (approx. 24 hours old) is probably the clearest danger sign for a persistent weak layers and means that there is not only a slab, but also a weak layer over a large area. It can therefore be assumed that avalanches of a similar size can also be expected in comparable terrain (exposure, altitude, steepness, topography). Such observations not only confirm a predicted persistent weak layers, but also the danger level depending on the additional load at which the slab was triggered.

Fresh slab avalanches that were observed before entering the open ski area are a danger sign. If they start while you are in the terrain, they are a clear warning sign.

After strong winds, fresh drift snow packs have formed in the lee on an existing weak layer, which have spontaneously descended as slab avalanches. The skier in the picture is at the same altitude and exposure, but in a windward-facing area (windward) from which the snow has been blown away. Based on her experience and knowledge of the area, she can identify these areas of terrain and, thanks to her experience, she knows that she must not leave this area. The danger signs were therefore recognised and evaluated, the appropriate terrain selected and the resulting risk assessed. With the measures ‘single skiing’ and ‘do not leave the windward corridor’, the risk for this group was acceptable. © snow institute I argonaut.pro
After strong winds, fresh drift snow packs have formed in the lee on an existing weak layer, which have spontaneously descended as slab avalanches. The skier in the picture is at the same altitude and exposure, but in a windward-facing area (windward) from which the snow has been blown away. Based on her experience and knowledge of the area, she can identify these areas of terrain and, thanks to her experience, she knows that she must not leave this area. The danger signs were therefore recognised and evaluated, the appropriate terrain selected and the resulting risk assessed. With the measures ‘single skiing’ and ‘do not leave the windward corridor’, the risk for this group was acceptable. © snow institute I argonaut.pro
These dry slab avalanches are spontaneous and in some cases have broken at different levels, i.e. there are several potential weak layers. The slab has typically formed near the crest (below the ridge) due to drifting snow. An older slab avalanche can be seen on the right. © snow institute I argonaut.pro
These dry slab avalanches are spontaneous and in some cases have broken at different levels, i.e. there are several potential weak layers. The slab has typically formed near the crest (below the ridge) due to drifting snow. An older slab avalanche can be seen on the right. © snow institute I argonaut.pro
This dry slab avalanche was triggered remotely by downhill skiers: The skiers initially broke the crystals of the weak layer spread over a large area (old snow problem), this breakage was able to propagate and then came off as a slab. The avalanche shown here fulfils all the criteria of a typical skier avalanche, which claims the most lives: Avalanche size: small/medium Rupture edge: approx. 50 cm high Rupture area: approx. 50 m x 80 m Avalanche length: approx. 150 m The depression below is a typical terrain trap, which can result in large burial depths even in such ‘small’ avalanches (after all, the rupture volume is approx. 2,000 m3). © snow institute I argonaut pro
This dry slab avalanche was triggered remotely by downhill skiers: The skiers initially broke the crystals of the weak layer spread over a large area (old snow problem), this breakage was able to propagate and then came off as a slab. The avalanche shown here fulfils all the criteria of a typical skier avalanche, which claims the most lives: Avalanche size: small/medium Rupture edge: approx. 50 cm high Rupture area: approx. 50 m x 80 m Avalanche length: approx. 150 m The depression below is a typical terrain trap, which can result in large burial depths even in such ‘small’ avalanches (after all, the rupture volume is approx. 2,000 m3). © snow institute I argonaut pro
After strong winds, fresh drift snow packs have formed in the lee on an existing weak layer, which have spontaneously descended as slab avalanches. The skier in the picture is at the same altitude and exposure, but in a windward-facing area (windward) from which the snow has been blown away. Based on her experience and knowledge of the area, she can identify these areas of terrain and, thanks to her experience, she knows that she must not leave this area. The danger signs were therefore recognised and evaluated, the appropriate terrain selected and the resulting risk assessed. With the measures ‘single skiing’ and ‘do not leave the windward corridor’, the risk for this group was acceptable. © snow institute I argonaut.pro
After strong winds, fresh drift snow packs have formed in the lee on an existing weak layer, which have spontaneously descended as slab avalanches. The skier in the picture is at the same altitude and exposure, but in a windward-facing area (windward) from which the snow has been blown away. Based on her experience and knowledge of the area, she can identify these areas of terrain and, thanks to her experience, she knows that she must not leave this area. The danger signs were therefore recognised and evaluated, the appropriate terrain selected and the resulting risk assessed. With the measures ‘single skiing’ and ‘do not leave the windward corridor’, the risk for this group was acceptable. © snow institute I argonaut.pro

Danger sign “wet snow”

If the snow cover is heavily soaked and no longer capable of bearing loads due to a lack of radiation, it loses its strength and wet snow avalanches form. Factors that favor this are rain, intense radiation, warm air temperature or high humidity and warm wind or the interaction of several of these factors. Wet snow avalanches are a clear danger sign that a wet snow problem exists at this exposure and altitude. It is not necessary for large wet snow avalanches to occur, even smaller avalanches are a sign that the snow cover snowpack is too “wet”.

A classic spring situation: the first wet snow avalanches have come loose from the steep gullies the day before. In the centre of the picture, a fresh avalanche is just about to start. The tracks were left by winter sports enthusiasts who skied down the firn in good time; the two fresh tracks on the right were filled in shortly before the photo was taken. Typical danger signs for a wet snow problem with diurnal progression are recognisable - which means: Leave in good time! © snow institute I argonaut.pro

Danger sign “gliding snow”

The probability of being buried by a gliding sluff gliding avalanche is low for winter sports enthusiasts. However, fish mouths and freshly fallen gliding sluff avalanches are a danger sign for this problem. These zones are avoided or crossed as quickly and individually as possible.

Only a few fish mouths can still be recognised. The sliding snow avalanche has already detached itself from most of them. © snow institute I argonaut.pro

Danger sign “bad gut feeling”

If you have a bad feeling in the pit of your stomach or anywhere else in the morning or before a run, this is a first-class danger sign that should be taken seriously. Although this feeling cannot be explained to others, it should not be ignored. Friends should also be expected to accept it and you should refrain or reschedule together. Even in the absence of any danger signs and a great feeling, something can always happen when freeriding. It would be all the more tragic if something went wrong despite the fact that someone in the group wasn’t feeling the good vibes – i.e. there was a sign.

Ideally, you should be travelling with friends you know well. So well that, on the one hand, you have no inhibitions about communicating your concerns and, on the other hand, the others realise when ‘something is not right’. If you don't feel like it, have a bad gut feeling or are simply having a bad day, it won't hurt anyone to stay on the piste or sit somewhere in the sun. © snow institute I argonaut.pro

Danger sign “other groups”

Other freeriders and groups can ruin your own plans. I or my group can ski down a slope individually, but if others board parallel to you, you are exposed to a higher risk. Winter sports enthusiasts crossing a slope above you can also increase the danger for you. Some lines cannot be skied if there are too many others on the slope or if communication with them is not possible.

If other freeriders are travelling in the same area, you also have to think about what ideas they might come up with ... © snow institute I argonaut.pro
02

Alarm signal

In contrast to danger signs, alarm signs require immediate action. They indicate “danger is imminent”. Once you have noticed an alarm signal, there is no time for collective policy discussions, generous rescheduling or simply ignoring it. Conversely, you shouldn’t go into action mode and panic and do anything rash. On the contrary – it is important to call on what you have learned and trained, to interpret the warning signs with your own experience and knowledge and to take the best possible action for yourself and your group depending on the situation.

“Poor visibility” alarm signal

Without visibility, you cannot judge the terrain around you. Leaving the secured ski area requires perfect knowledge of the area and knowledge of the current conditions. But even if you have this, the risk increases enormously when visibility is poor, as it is then more difficult and time-consuming to perceive, communicate and rescue in the event of an emergency or accident.

Whiteout. Great snow, but virtually no visibility. The terrain above and below you can no longer be assessed, danger signs are no longer recognised, an accident or avalanche will probably not be seen/noticed by others and orientation by sight is no longer possible. Possible measures: Get to the piste/known terrain as quickly as possible and ensure continuous communication (visual contact, buddy system, shorter sections, etc.). © snow institute I argonaut.pro

Alarm signal “Bad gut feeling”

If you have a bad feeling when leaving the secured ski area or get a bad feeling when looking at a slope, you need to react. You need to communicate your concerns and take a more defensive line. And please: never try to persuade someone to do something – and never let them persuade you to do something you have a bad gut feeling about!

Even if there are no external danger signs, the weather and the group are suitable and the quantity and quality of snow are perfect. Especially if you are standing directly in front of a slope or an important decision and you get a bad feeling, this is an alarm signal that must result in a ‘stop’. © snow institute I argonaut.pro

“Terrain trap” alarm signal

If a terrain trap is detected, you must react immediately and avoid the terrain. It is particularly important to avoid hollows, drop-offs, streams, rocks, woodland, etc. below large slopes.

The mistake has already been made: A narrow, half-snow-covered stream bed that you can't get out of because the flanks to the left and right are too steep. A small avalanche or a sluff is enough to bury you metres deep in the stream. Even a fall can have fatal consequences. © argonaut.pro

“Fresh avalanches” alarm signal

Nothing is scarier than triggering a snow slab during a run or when entering a slope. Regardless of whether you trigger it directly or remotely – it is a sure sign that something has gone wrong in the decision-making process and needs to be corrected.

The freerider has just triggered a small snow slab. No reason to panic, but an alarm signal to press the stop button and rethink and re-evaluate the decision - the choice of line. An alternative must be found! In some situations (e.g. when entering a narrow gully), the terrain chamber can also be defused after the departure of a snow slab - this may or may not be the case. © snow institute I argonaut.pro

Alarm signal “whamming noises and cracks”

The famous shot across the bow: you have destroyed the existing weak layer, it has broken and settled, which can be clearly heard as an impressive “whump” sound due to the air being pushed out and/or can be seen as a crack or cracks forming. If you’re lucky, it’s not steep enough or the weak layer isn’t continuous enough to prevent a snow slab from coming loose. But there’s not much missing and it’s a clear warning sign to press the stop button! This means: don’t let anyone follow you and get out of the slope as quickly and safely as possible.

Such whumpfing collapsing sounds (“whump” noises) are often heard next to streams in flat terrain, because the moist air there causes many large, angular crystals to form on the snow surface, which – when snowed in – form perfect weak layers that collapse impressively. In flat areas, however, they do not pose a danger to winter sports enthusiasts and cannot be transferred to other slopes.

© snow institute I Walter Würtl
If you have never triggered a whamming noise or a crack in the terrain, you don't need to worry about not recognising these alarm signals in an emergency. Both events are extremely impressive and often occur together. In the photo, a group has caused the weak layer to collapse in a massive old snow problem and danger level 4. The wind signs and fresh drift snow deposits are clearly visible. © snow institute I Walter Würtl
03

Wind sign

As mentioned above under hazard signs “drift snow”, wind signs are helpful in recognizing drift snow packs. Drift snow packs are usually well bound and therefore a perfect slab and can – if a weak layer and other conditions are present – descend as a slab avalanche. However, because not all wind signs are danger signs that indicate fresh drift snow, we have summarized all (or at least most) of them here:

© snow institute I LWD Tirol
© snow institute I LWD Tirol
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
© snow institute I argonaut.pro
04

Conclusion

Before and during freeriding, all senses must be activated and the terrain must be constantly scanned!

Danger signs are used to verify the weather and avalanche forecast. They can be used to check whether the conditions on site are as expected. If not, the planned runs must be adjusted, rescheduled or canceled based on these new findings. If the conditions are better – i.e. there are no corresponding danger signs – more risk can of course be taken than planned.

Alarm signs are clear indications that you are currently in the wrong place and should leave it as smoothly as possible. Ideally, you will not be confronted with such alarm signals during the descent.

© snow institute
© snow institute

The most important message in this context is also here:

"If the snow is the problem, the terrain is the solution!"

Wild Walt
Cover picture: © snow institute | argonaut.pro

Teaching materials on the topic:

Presentation: Snow and avalanches

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