Verhalten abseits der Piste Avalanche accidents Wissenswertes über Lawinen Literatur Kernteam Lawinenausbildung Exceptional avalanche situations
Explanation of danger levels
avalanche danger expressed in the avalanche danger scale increases from level
to level. At the same time, the snowpack stability decreases (cf. Figure 1) and
the prevalence of avalanche prone locations in open terrain increases.
Generally speaking, the additional load required to trigger an avalanche
decreases at the higher levels. The higher the danger level, the larger the
avalanche size and number of avalanches.
Fig. 1: Occurrence of stability categories with
danger levels low (level 1) to considerable (level 3). As the danger level
increases, so does the proportion of areas where stability is low. Also note
the proportion of areas where the stability is poor when the danger level is
moderate (level 2).
The avalanche bulletin indicates any changes in the danger level that are expected to arise during the day covered by the forecast. Examples:
The description of the avalanche danger can differ under the separate headings "danger description" and "additional danger".
substantial danger of full-depth avalanches exists and this danger is greater,
over a wide area, than the danger of dry slab avalanches, two maps are produced
to show both the danger of dry slab avalanches and the danger of full-depth
avalanches Note in this case that the danger
of full-depth avalanches does not vary during the day. Both dry slab and
full-depth avalanches can therefore occur at any time of day (including in the
Occurrence in percent of individual danger levels in the avalanche bulletin
(evening assessment (5 pm) from 01.12. until 30.04.) from winter 1997/88 to
Low avalanche danger (level 1):
snowpack is generally well bonded or, as a whole, loosely packed. Such
conditions frequently occur in mid-winter during long spells of fine weather
accompanied by shallow snow cover. When either one of these conditions
prevails, a fracture is usually unable to propagate in the snowpack.
Moderate avalanche danger (level 2):
snowpack is only moderately well bonded (cf. Fig. 1) in some places, as
generally specified in the avalanche bulletin by reference to the altitude
zone, aspect or type of terrain. Provided that routes are selected carefully,
the conditions for snow sport activities are favourable in the majority of
Considerable avalanche danger (level 3):
slopes the bonding of the snowpack is only moderate to weak (cf. Fig. 1).
Triggering is possible even with small additional loads,
especially on the steep slopes in the indicated aspects and altitude zones
stated in the avalanche bulletin. Alarm signs typically exist, but not in every
case. Isolated slab avalanches can be released even from well outside the
starting zone (remote triggering).
High avalanche danger (level 4):
snowpack is weakly bonded on most slopes. Triggering is probable even by small
additional loads on numerous steep slopes. Alarm signs often exist. Natural
avalanches and remote triggering are typical. In certain cases, when the
avalanches are not especially large, snow sport participants are most
endangered. Frequently, however, parts of transportation routes and settlements
are exposed to danger. Depending on the situation (e.g. snowpack structure, new snow, wind), numerous medium-sized natural avalanches and a
greater prevalence of large avalanches, which generally follow familiar paths,
are to be expected. Exposed parts of transportation routes and settlements in
the areas affected by such avalanches are endangered in the majority of cases.
Safety measures, such as the use of explosives or closures, are to be
recommended in these places. The conditions outside marked and open pistes are
unfavourable. Avalanche runout zones in particular warrant caution.
Very high avalanche danger (level 5):
The snowpack is generally weakly bonded and therefore largely unstable
(consistent with large quantities of new snow accompanied by a fracture
within same, or at transitions between new snow and the old snowpack).
Extensive weak layers can also exist deep inside the snowpack; these can collapse if exposed to a heavy burden of overlying snow and give rise to large or very
large avalanches. Numerous large and, in many cases, very large natural
avalanches are to be expected, including in moderately steep terrain.
Avalanches can also occur in the same place several times and open up new paths.
Extensive safety measures (closures and, in some circumstances, evacuation
etc.) are required. Fortunately, such disaster situations warranting danger
level 5 very rarely arise. In such instances, backcountry touring is not
recommended and is usually impossible in any case.