Slight snowdrift problem + wet-snow problem amid typical April weather

Last week was marked by variable April weather conditions, avalanche danger considerable regionally at the start then moderate then low. Wet-snow and snowdrifts were the prevalent problems. Two avalanche incidents involving persons occurred: on 20.04 two persons below the Liebenerspitze in the Gurgler Massif were caught in a slab avalanche. On 19.04 the snow melted on a slope near the Arzler Scharte, revealing a person who was buried in snow presumably on 30.01. The avalanche situation is not expected to change significantly. Major focus should be on the thoroughly wet snowpack at high altitudes.

In high-alpine regions on Main Alpine Ridge, still wintery conditions. Elsewhere, springtime has arrived.

As already referred to in the last Blog , precipitation from 16-17 April on the Main Alpine Ridge brought measurable amounts of fresh snow. For that reason, the wintery character persists there, whereas at low and intermediate altitudes the spring has already started its march forward. Due to high precipitation intensity and massive wind impact, large-to-very-large slab avalanches triggered in high-alpine terrain at that time. The primary fracture occurred in near-surface layers in the fresh snowfall mass. The large additional loading of these slab avalanches led to fracture of a near-ground level weak layer which formed in early winter and was, particularly in glaciated terrain, evident over widespread areas.

Blick ins Gaisbergtal in der Gurgler Gruppe. Am Foto erkennt man spontane Lawinenabgänge vom 17.04. und 18.04.2025 (© Ronald Krumpens, 20.04.2025)
View into Gaisbergtal in the Gurgler Massif. Visible in the photo: imposing naturally triggered avalanches on 17-18.04.2025. (©Ronald Krumpens, 20.04.2025)
Schneebrettlawine im hochalpinen Gelände in den Zentralen Stubaier Alpen im Bereich des Alpenhauptkammes (LWD Tirol, 23.04.2025)
Slab avalanche in high-alpine terrain in the central Stubai Alps, near the Main Alpine Ridge (LWD Tirol, 23.04.2025)
Für Skitouren muss man inzwischen in höheren Lagen unterwegs sein. Sellrainer Berge (©LWD Tirol, 19.04.2025)
For backcountry skiing tours, you have to venture up to higher altitudes. Sellrain mountains (©LWD Tirol, 19.04.2025)
Der Frühling hält Einzug. Inzwischen sind die meisten Skigebiete geschlossen, wie hier im Kühtai. (©LWD Tirol, 19.04.2025)
Springtime is marching in. In the interim, most of the ski areas have closed, as above in the Kühtai. (©LWD Tirol, 19.04.2025)

In case of southern barrier cloud regions, there is invariably a large portion of precipitation which falls immediately onto the Main Alpine Ridge. This was also the case on 16-17 April, most conspiculously in the Gurgler Massif. Easy to recognize in the two following weather station graphs from Obergurgl and Timmelsjoch.

Niederschlag bei der Wetterstation Obergurgl
Precipitation at weather station Obergurgl
Deutlich mehr Niederschlag bei der Station Timmelsjoch. (vgl. voriges Bild: Wetterstation Obergurgl)
Much more precipitation at the Timmelsjoch station. (compare with previous depiction: weather station Obergurgl)
Ein schneearmer Winter geht zu Ende. Beobachter-Auzeichnungen aus Obergurgl
A winter poor in snowfall slowly winds to a close. Observer depictions from Obergurgl.

Avalanche incident Liebenerspitze

On 20.04 below the Liebenerspitze in the Gurgler Massif at about 3300m on an extremely steep west-facing slope, a slab avalanche triggered when two persons were in their ascent (using crampons). The avalanche caught two persons and swept them over rocky terrain. They were not buried or only partially buried. One person was severely injured, the other escaped with only minor injuries. Together with the Alpine Police, we carried out an investigation of the incident on the spot. What was revealed: a weak layer inside the mass of fresh fallen snow (deposited with accompanying wind-impact starting on 16.04) triggered the slab avalanche.

Lawinenabgang unterhalb der Liebenerspitze. Die Personen wurden über felsdurchsetztes Gelände mitgerissen. (©Ronald Ribis, 20.04.2025)
Avalanche release below the Liebenerspitze. The persons were swept over rocky terrain. (©Ronald Ribis, 20.04.2025)

A snow profile near the avalanche incident was taken. Significant for the avalanche release were the recently-formed weak layers consisting of decomposed snow crystals inside the mass of fresh fallen snow.

Schneeprofil, welches im Nahbereich der Unfalllawine am Anriss einer spontanen, sehr großen Lawine vom 18.04. aufgenommen wurde. Im oberen Bereich des Profils traten nur mehr Teilbrüche im Neuschnee auf. Die Schwachschicht im Bodennähe zwischen Schmelzkrusten war für den Abgang der sehr großen spontanen Lawine verantwortlich und hatte mit dem Lawinenabgang mit Personenbeteiligung nichts zu tun.
Snow profile taken near the avalanche incident fracture of a naturally triggered, very large avalanche release on 18.04. In the uppermost layers of the snowpack, the moment of release is recognizable through the still trigger-sensitive weak layers. The layer of depth hoar near ground level between melt-freeze crusts, on the other hand, was responsible for the release of the very large naturally triggered avalanche and had nothing to do with the avalanche involving persons.

Unterstützt wurden wir bei unseren Erhebungen von der Flugpolizei (© LWD Tirol, 23.04.2025)
With the assistance of the Airbourne Police, we were able to carry out our investigation. (© LWD Tirol, 23.04.2025)

Avalanche incident Arzlerscharte

On 19 April a report came into Tirol headquarters that an avalanche release had occurred below the Arzlerscharte in the Karwendel. Hikers found a body segment on the bare slope where the snow had recently melted. It was a person who had been missing since the end of January. This person was totally buried by a slab which had triggered on a very steep west-facing slope. Once this uncovery become known, a photo from 02.02 was published on which the avalanche incident, coincidentally, was depicted. Our researches led to the ultimate revelation: the avalanche released during a period of high avalanche activity, in all probability on 30 January 2025.

Fundstelle des Opfers und Stoßrichtung der Lawine unterhalb der Arzlerscharte (© Alpinpolizei, 20.04.2025)
Place of discovery of the victim and plummet path of the avalanche beneath the Arzlerscharte (© Alpinpolizei, 20.04.2025)
Foto vom 02.02., welches zufällig die Unfalllawine zeigt (© Maximilian Meiselberger)
Photo from 2 February on which the avalanche incident was coincidentally depicted. (© Maximilian Meiselberger)

April weather will continue, but it’s getting warmer.

Following a cold front which brought a small amount of fresh fallen snow up to 2000m in Tirol, temperatures will now continue their upward march. Weather conditions will remain, to start with, rather variable.

Aktuell etwas Neuschnee im Gebirge.
Currently, some fresh snow in the mountains.
Wetterstationsgrafik Galzig. Der Niederschlag vom 23.04. auf den 24.04. ging in dieser Höhenlage großteils als Regen nieder. Gut zu erkennen die markante Abkühlung.
Weather station graph Galzig. The precipitation from 23 to 24 April arrived mostly as rainfall at this altitude. Easily visible in the above graph: the marked drop in temperature.

Avalanche danger

Currently, avalanche danger is dependent on altitude. Above approximately 2600m there exists a minor snowdrift problem. Potential weak layers for recently generated snowdrift accumulations occur esp. in a frequently observed, quite marked near-surface layer of graupel. Below approximately 2600m over the next few days, a possible loss of firmness due to the thoroughly wet snowpack is what requires the uppermost attentiveness of backcountry tourers. In regions with fresh fallen snow, small loose snowslides can be expected in rocky terrain.

Graupel im Nahbereich der Schneeoberfläche. Gurgler Gruppe im hochalpinen Gelände (LWD Tirol, 23.04.2025)
Graupel near the surface. Gurgler Massif in high-alpine terrain (LWD Tirol, 23.04.2025)