Numerous naturally triggered avalanches
Numerous avalanches unleashed naturally in Tirol during this last week. These occurred primarily on steep, sunny slopes up to altitudes of approximately 2700 m. Wet-snow and glide-snow avalanches were frequently observed below about 2400 m.
 |
| Deposits of fresh wet-snow avalanches on Fliesser Berg, south, 2100 m (photo: 23.02.2021) |
 |
| Slab, glide-snow and loosely-snow avalanches in the Samnaun Massif. At left edge of photo a glide crack is visible, indicator of potential glide-snow avalanche (photo: 23.02.2021) |
 |
| A palpable threat to exposed transportation routes, Gschnitztal, photo: 23.02.2021 |
 |
| Naturally triggered avalanches in extremely steep south-facing terrain. Central Lechtal Alps (photo: 23.02.2021) |
 |
| Small glide-snow avalanche, huge effect. This avalanche buried the approach road to Kals. see also photo below (photo: 23.02.2021) |
 |
| Avalanche deposits from above avalanche on Kalser Landesstrasse (photo: 23.02.2021) |
Successful artificial triggerings
Due to heightened potential danger to certain sectors of roads in East Tirol where snow has been heavy, avalanches were also artificially triggered from a helicopter. Since these were carried out at the right moment, they achieved great success, as the following video shows.
Due to heightened potential danger to certain sectors of roads in East Tirol where snow has been heavy, avalanches were also artificially triggered from a helicopter. Since these were carried out at the right moment, they achieved great success, as the following video shows.
Artificially triggererd avalanche to ensure safety of Kalser Landesstrasse (video: 24.02.2021)
A list of recent avalanches involving persons and rescue operations
Several avalanches were reported which involved persons and required rescue operations as a result of the unclear situation. According to our information, there were no injuries. Here is a rough list:
17.02.2021 11:50 am: Nederkogel, Gurgler Massif, southeast, 2650m,
20.02.2021 09:50 am: Lämpermahdspitze, northern Ötztal and Stubai Alps, east, 2400m
20.02.2021 09:50 am: Lämpermahdspitze, northern Ötztal and Stubai Alps, east, 2400m
20.02.2021 11:35 am: Vordere Brandjochspitze, Karwendel, southeast, 2250m
20.02.2021 --:-- am : Kesselspitze, northern Ötztal and Stubai Alps, northeast, 2300m
21.02.2021 1:15 pm: Hohe Warte, western Tux Alps, north, 2250m
23.02.2021 5:40 pm: Arzler Reise, Karwendel, south, 1950m
24.02.2021 11:00 am: Foppmandl, central Stubai Alps, northeast, 2350m
24.02.2021 12:15 pm: Kleiner Kaserer - Wildlahnertal, western Tux Alps, southwest, 2100m
24.02.2021 3:15 pm: Arztaler Hochleger, western Tux Alps, 2200m, south
25.02.2021 7:45 am: Zirmeggenkar, Gurgler Massif
25.02.2021 12:45 pm: Riffelsee Talabfahrt, Weisskugel Massif
25.02.2021 2:15 pm: Schafkar, Lechtal Alps, southeast, 2300m
25.02.2021 3:50 pm: Gleierschköpfe, Karwendel
 |
| Nighttime operation Arzler Reise, Karwendel (photo: 23.02.2021) |
 |
| Avalanche rescue operation Arztal-Hochleger (photo: 24.02.2021) |
 |
| Avalanche Foppmandl (photo: 24.02.2021) |
 |
| Slab avalanche Kleiner Kaserer, Wildlahnertal (photo: 24.02.2021) |
 |
| Avalanche Zirmeggenkar (photo: 25.02.2021) |
 |
Slab avalanche Schafkar (photo: 25.02.2021) |
Systematic snowpack analysis as basis of danger evaluation
Over recent days we have concentrated our efforts on observations of the increasing degree to which the snowpack is moistening or becoming thoroughly wet. In the context of a large-scale exploratory tour of the terrain with the help of a state helicopter we were able to systematically examine and analyze the snowpack.
 |
| A landing at weather station Gallreideschrofen, Pitztal (photo: 23.02.2021) |
We utilized this opportunity to also verify the snowpack simulations which had been programmed at some of the weather stations. The results amazed us: reality and model fit together perfectly.
 |
| Steady rise in temperature, adequate nocturnal outgoing radiation and cooling, daytime moistening of snowpack - Gallreideschrofen station. |
 |
| Snow profile in vicinity of Gallreideschrofen weather station, east-facing slopes, 2190m, isotherm snowpack, i.e. thoroughly wet and 0°C. Potential weak layers inside the snowpack |
 |
| Snowpack simulation: at left, red triangles and squares show potential weak spots based on wet-snow indicators; at right, simulated snow profile for Gallreideschrofen location. |
 |
| A few metres distant from above snow profile, a 23° NW slope: the snowpack still has cold reserves, i.e. the warmth is not yet harming the snowpack on shady slopes at that altitude. |
 |
| Map of EUREGIO region with wet-snow indicators for selected stations and simulated south-facing slopes: the redder the color, the more instable the spot |
Dust blown northwards from the Sahara desert provided a special fascination, turning the atmosphere quite hazy on 22 - 24 February.
 |
 |
| Dust from the Sahara can frequently be found on or near the snowpack surface, stemming from the beginning of February. This reinforces the absorption of warmth in the snowpack, thereby increasing the degree to which it becomes wet. (photo: 23.02.2021) |
Outlook for the next few days
The springlike conditions, including a daytime cycle of avalanche danger, will remain intact to start with. A weak cold front will reach Tirol on Friday night and lead to an improvement of the situation, i.e. a lesser daytime danger cycle than was the case this last week. Starting on Sunday, 28 February, a new, stable high-pressure front is expected to reach Tirol.
The main danger will be glide-snow avalanches which can slide across steep grass-covered slopes. These avalanches can release at any time of day or night, even when there is a melt-freeze crust capable of bearing loads. For that reason, our recommendation: circumvent / avoid all zones below glide cracks. In East Tirol where snowfall has been heaviest, glide-snow avalanches can still grow to dangerously large size and place hiking trails or forest roads at risk.
 |
| Glide-snow avalanches which have already released and glide-snow fractures, Northern Massif above Innsbruck (photo: 24.02.2021) |
For winter sports enthusiasts the rule of thumb is: plan backcountry tours well, i.e. time allotment is all-important following nights of clear skies. Apart from the glide-snow problem, conditions are good. During the morning there is also danger of taking a fall on the hard-frozen snowpack surface. Near combs and ridges, cornices are in danger of breaking.
