Very high avalanche danger in western North Tirol

By Tuesday morning, 15.01, up to 150 cm of fresh snow is forecast in western regions of North Tirol. Elsewhere 50-90 cm of fresh snow is expected widespread. The precipitation will come with great intensity, accompanied by storm-strengh NW winds.

Forecast fresh snow by Tuesday morning, 15.01, including settling.

Lots of fresh snow forecast in the Silvretta region. Winds will be strong.

Storm-strength NW winds ensure wide-ranging snow transport of the fresh snow throughout the land.

Temporary rise in temperatures on Sunday night, 14.01. (©meteoblue)

At Plojen weather station in the Samnaun group, nearly 50 cm of fresh snow was registered by 5:00 pm today, Sunday 13.01. Winds were blowing at strong velocity in many places.

As a result of the snowfall intensity and temporarily higher temperatures, especially on Sunday night (14.01), high naturally triggered avalanche activity is expected. Primarily in the major areas of precipitation, avalanche danger level 5, Very High, is possible, with very large, in isolated cases extremely large avalanches  possible. This is particularly the case in high altitude starting zones which lie in leeward areas. Observers from Ausserfern have already reported increasingly frequent naturally triggered avalanches during the evening of 13.01.

As the snowfall level ascends to approximately 1400 m, we also expect a significant increase in glide-snow activity at low and intermediate altitudes

Snowpack layering

The brief interim of pleasant weather on Friday, 11.01, permitted us to sharpen our understanding of the current snowpack layering.

As already reported in earlier blog entries, no area-wide, trigger-sensitive weak layers are evident in the lower section of the snowpack. Only one layer of faceted snow crystals near a melt-freeze crust from 06 December might still exist between 2200 and 2700 m. In North Tirol and in northern regions of East Tirol, this weak layer should now be heavily covered over,  only triggerable by the weight of another releasing avalanche.

About 30 cm above the ground, there are faceted snow crystals near a melt-freeze crust (06.12.2018) evident. This weak layer is covered over by deep layers, but can potentially still be triggered by large additional loading.

In the upper section of the snowpack in southern regions between 1600 and 2100 m, faceted crystals have also formed, partly near a melt-freeze crust, in accordance with Danger Pattern 4 (cold on warm - warm on cold) presumably around the 8th of January. This weak layer was covered by fresh snow in the most recent round of precipitation. Fracturing a slab avalanche from this layer due to the weight of fresh snow on the snowpack is quite possible.

Apart from the above-described layers of faceted snow crystals, the light, fluffy snowfall which fell on Friday, 11.01 and Saturday 12.01 is of particular importance for slab avalanches: it is a particularly trigger-sensitive weak layer and can be easily triggered at all altitudes and in all aspects, even below the timberline.

The small amounts of snowfall on Friday night, 12.01, were deposited as loosely-packed, light and fluffy snow. Now covered, this snow is a particularly trigger-sensitive weak layer.

Naturally triggered avalanches on house roofs in St. Johann in Tirol: the light, fluffy snow is here a weak layer for the fresh snow which fell on Saturday night, 13.01.  (photo: 13.01.2019)

Yesterday, Saturday 12.01, our Avalanche Warning Service team member Christoph attempted to test the fracture propagation tendencies of the light, fluffy snow beneath the snowdrifts on the Seegrube:

In general, current conditions for winter sports in outlying terrain are quite unfavourable. On slopes with less than 30° gradient there is hardly any pleasure in skiing down through the knee-deep snow. In forested terrain, the danger of branches breaking off and trees falling is added to the negative overall balance. Also the “deep snow risk” needs to be taken into consideration, as mentioned in the last Blog . In the regions where snowfall has been heaviest, particularly near trees, the risk of sinking meter-deep into the snow is also a threat.

Many trees are cloaked in a mantle of snow, providing the wind with an ample surface to blow against. Ongoing storm winds will presumably cause much damage to the forests.  (photo: 11.01.2019)

The positive side: the avalanche situation will improve very rapidly following the current round of precipitation. Thereafter, we expect relatively safe and good conditions for backcountry ski touring.

Below, a few impressions from the last few days:

Stamina test for weather stations  (photo: 11.01.2019)

Avalanche protection measures are already burdened to the brim in some places. Region Wilder Kaiser.  (photo: 11.01.2019)

Deep wintery conditions on the Seegrube (1905 m) above Innsbruck. Snow depths are over 4 meters.  (photo: 11.01.2019)

St. Valentine’s high alpine chapel in the Zillergrund is hardly recognizable.  (photo: 12.01.2019)

Heavy wind impact above the timberline. Füssener Jöchle. Allgäu Alps.  (photo: 12.01.2019)

Heavy snow padding on a trailside crucifix below Pfoner Kreuzjöchl.  (photo: 12.01.2019)

Fracture of a very large avalanche in the eastern Lechtal Alps. The avalanche triggered naturally during the precipitation of 9-11 January.  (photo: 12.01.2019)

This avalanche plummeted over the Brand-Mitteregg snow shed on the state road between Berwang and Manlos, causing damages to the forest.  (photo: 12.01.2019)

Slab avalanche on the Schartenkogel, north-slope, 2200 m. The snowdrift accumulation was presumably triggered when a cornice broke.  (photo: 12.01.2019)

Presumably a glide-snow avalanche which unleashed as a powder-cloud avalanche. Northern Zillertal Alps.  (photo: 12.01.2019)

Numerous covered glide-snow avalanche fractures in northern regions.  (photo: 11.01.2019)

Intense glide-snow activity, also in the Allgäu Alps.  (photo: 12.01.2019)

Formidable winds and fresh snow causing treacherous avalanche situation

Current situation

The avalanche situation is currently very treacherous, particularly in North Tirol and in northern regions of East Tirol. The threat stems from wide-ranging snowdrift accumulations which are found in all aspects at and above the timberline, especially in gullies, bowls and behind protruberances in open terrain. It is still quite cold in the mountains, the snowdrifts thus remain prone to triggering and are easily dislodged by even the weight of one sole backcountry skier. Since the wind has incrementally slackened off since yesterday evening (09.01) the snowdrift accumulations are frequently covered, making them difficult to recognize.

Friday (11.01) promises to be sunnier, for the first time in a while in North Tirol. In combination with the above-described snowpack layering, a thoroughly risky and accident-prone day awaits us. We advise all backcountry skiers and freeriders to be utterly defensive in their conduct in outlying terrain. The inexperienced should not leave the secured and marked ski runs.

Ongoingly, as a result of the forecast solar radiation, naturally triggered avalanches can be expected in isolated cases tomorrow, particularly on SW to S to SE facing slopes. These releases can attain large-to-very-large size in the main areas of precipitation along the Bavarian border (avalanche sizes).

The snowpack remains prone to triggering (Northern Massif)  (photo: 09.01.2019)

All the way down to the valley floor, the snow cover is far deeper than usual for this juncture of the season. Glide-snow avalanches on steep, grass-covered slopes can grow to impressively large size and become a danger not only to skiers and freeriders, but also put transportation routes and buildings at risk. The problematic factor is this: glide-snow avalanches are utterly unpredictable, can release over the ground at any time of day or night. For that reason, zones below glide cracks in the snowpack surface should be avoided.

High risk of danger from glide-snow avalanches prevails widespread in Tirol, as here in the Tux Alps. Contrary to widely held opinion, a glide crack is not a sign of improving conditions, but quite the contrary, in most cases is an indicator of imminent danger of a glide-snow avalanche. (photo: 08.01.2019)

Apart from trigger-sensitive snowdrift accumulations, in East Tirol south of the Main Alpine Ridge and north of the Drau, it is still possible for avalanches to trigger in the old snow. The most threatening potential layer is one of faceted crystals which formed around the melt-freeze crust on 6 December (GM4). Avalanche prone locations are found in all aspects between about 2200 and 2700 m and in general in very steep terrain. This weak layer can generally be triggered only by large additional loading. In places where the snow is shallow, however, there are also possible “hotspots” where even minimum additional loading can trigger an avalanche.

The immense amount of snow threatens more than the obvious danger of avalanches. Accidents in Salzburg and in Switzerland  demonstrated just how fast a skiing accident in meter-deep, unbonded fresh snow can end in tragedy. It can sometimes be quite difficult to free oneself after a fall in deep snow. If your head is buried in snow, the risk of suffocation makes it more difficult still. What counts here is keeping your skiing partners in immediate view in order to react as quickly as possible when necessary. As in avalanches, the person buried usually has only a few minutes of survival. If such a person is not immediately found, the avalanche sensor device can help to pinpoint the victim.

Slope closures must be heeded without question.  photo: 10.01.2019)

Review

Several days with reams of fresh snow and storm-strength winds are behind us. Since the launch of this period of snowfall on Tuesday morning (07.01) there has been a great deal of fresh snow registered in far reaching areas of Tirol. Most of it fell in the northern barrier-cloud regions, from the Lechtal and Allgäu Alps over the Karwendel to the Wilder Kaiser. As so often to date this winter, the precipitation was accompanied by storm-strength winds in many places.

Amounts of settled fresh snow between Monday, 07.01 and Thursday, 10.01.

Storm-strength northwesterly winds.

Stormy: Stubai Glacier  (photo: 07.01.2019)

Interesting effects of extreme snow depths: the temperature sensor on the Seegrube has been buried in snow since 05.01. Apparently it lies 108 cm beneath the snowpack surface.

Snowfall was most intensive on Tuesday night and the early hours of 09.01. During this time window the apogee of naturally triggered avalanche activity was also reached. The loosely-packed fresh snow was swept into the plummet paths of slab avalanches so that truly imposing powder-cloud avalanches developed in extremely steep terrain.

Every single one of the avalanches we are aware of and which poured over roads were either glide-snow or loosely-bonded snow avalanches. Tomorrow, Friday, when visibility improves, we can obtain a more comprehensive overview of the situation.

A glide-snow avalanche displaced a community road in the Astegg district of Finkenberg.  (photo: 07.01.2019)

On Wednesday, 09.01, there was an avalanche accident in Zammermoos, below the Galzig in the outlying terrain of the St. Anton am Arlberg skiing region. A 16-year old Australian lost his life. The avalanche was about 140 m long, about 45 m wide on average and triggered on a 45° gradient slope. The fracture depth of the avalanche varied from about 20 cm to 100 cm (For details go to LAWIS). The weak layer was a very thin layer of faceted and decomposed snow crystals which had formed only recently as a result of the temperature disparities during the snowfall (danger pattern: cold on warm). In addition, there was also graupel found in the uppermost layers of the snowpack, although not so prevalent as to be the primary weak layer.

Avalanche release Zammermoos on 09.01.2019. The place of burial is marked.  (photo: 10.01.2019) 

At the Ulmerhütte weather station in the vicinity of the accident spot the temperature fluctuations of the last week are visible, a requirement for the danger pattern Cold-on-Warm.

While North Tirol was immersed in snow, southern regions were at a loss. Precipitation reached the Dolomites, but the amounts were extremely modest.  (Connyalm: 7cm; Porzehütte: 2cm).

Very little precipitation: observers in Obertilliach are still waiting for the very first snowfall of the winter.

Great precipitation: in the last 7 days on Pillersee in the Waidring Alps, about 140 mm of precipitation was measured.

Outlook

A temporary improvement in weather is anticipated on Friday 11.01, as mentioned above. Winds will be light to moderate from the north, somewhat stronger on the Main Alpine Ridge and in East Tirol north of the Drau. Due to the low temperatures, no significant improvement in the avalanche situation is expected. On Saturday, as a result of light snowfall and intensifying winds, the next front will make its entrance. From today’s perspective, things will turn serious again on Sunday and on Monday. We expect heavy snowfall once again, which will bring us immense amounts of fresh snow in the Arlberg region and on the Main Alpine Ridge more than anywhere else.

An update will be published in the next few days...

 The snowpack will grow further at the beginning of next week. Northern Massif. (photo: 10.01.2019)

Persistent high avalanche danger in North Tirol + northern East Tirol

The avalanche situation in the Eastern Alps is currently quite tense. From the Ybbstal Alps in Lower Austria all the way to the Bregenzerwald in Vorarlberg, high avalanche danger (level 4) prevails over widespread areas above the timberline.

High avalanche danger, level 4, in far-reaching parts of Austria   (www.lawinen.at)

There has been 100 cm of fresh snow registered over widespread areas in North Tirol during the last few days. Significantly more in some regions, e.g. Waidring and Kitzbühel Alps, Hohe Tauern and Karwendel. In the southern regions of East Tirol there was only a few centimeters of fresh snow registered. The snowfall level was predominantly at the valley floor. Precipitation was accompanied by storm-strength NW winds, leading to massive snow transport of the loosely-packed fresh snow everywhere above the treeline.

Snow depths in North Tirol grew about 100 cm over the last eight days.

At the observation stations in Boden and on the Northern Massif, snow depths are far above average currently (since 1960, or 1973). More than 200 cm of fresh snow has been registered in the Northern Massif since 30 December. Such a magnitude of snowfall has never before (since 1973)  been measured at such an early juncture of the season.

Indicative of the current weather situation in North Tirol in recent days: lots of fresh snow and strong winds.
Weather station Breiter Grieskogel, Grieskogel group.

Intensive snowfall has been observed down to low lying areas during the last few days.  (photo: 04.01.2019)

Wintery conditions also in the western sector of the Tux Alps  (photo: 06.01.2019)

As a consequence of intensive snow transport, avalanche danger levels also increased throughout North Tirol, as well as in the Hohe Tauern, to level 4: High. Numerous roads had to be closed. Also lifts were shut down because of the inordinately strong winds.

The large-sized avalanches we are aware of, e.g. in the Zillertal Alps, presumably fractured inside the fresh snow and fresh snowdrifts. On 5 January we received the report of an avalanche release on the Fernpass road. As was demonstrated upon closer inspection, this was actually a snowslide caused by nearby trees unloading their burden of snow onto the ground.

Massive snow transport generated wide-ranging snowdrift accumulations above the timberline. Slab avalanches often released inside the layers of fresh snow and fresh snowdrifts. Gurgler group  (photo: 07.01.2019).

The next significant front will reach us tomorrow, Tuesday, 8 January 2019. Amounts of 50-120 cm of fresh snow can be expected as a result of heavy precipitation between Tuesday morning and Thursday morning. Most of the precipitation is expected to fall north of the Inn and in the western regions of North Tirol. The snowfall level will be at approximately 1000 m to start with, then on Tuesday night drop down to low lying areas. The precipitation will again be accompanied by storm-strength NW winds, which in turn will bring about enormous snow transport.

Lots of snow and wind: on crests, huge cornices can be expected to form. (photo: 04.01.2019)

When the next front arrives, the already prevalent danger pattern will alter only very slightly. As a result of the precipitation and strong-to-stormy NW winds, fresh and trigger-sensitive snowdrift accumulations will form anew starting on Tuesday morning, 8 January 2019. These drifted masses will trigger naturally in leeward zones behind crests and terrain edges in particular, as medium-sized, in the major areas of precipitation also large-sized, in isolated cases even very large-sized avalanches.

Extremely large-sized avalanches currently appear quite unlikely due to the current snowpack structure, since no area-wide, cohesive, more deeply embedded weak layers exist from which slab avalanches could fracture.

On steep grass-covered slopes, in addition, glide-snow avalanches can be expected at any time of day or night. These releases can also grow to large size, due to the enormous snow depths currently. Areas below glide cracks in the snowpack surface should be consequently avoided.

Snow block glided away as a consequence of a cornice breaking.  (photo: 07.01.2019)

The current snow and avalanche situation can be attributed to an unfavourable, quite stable large-scale weather zone: a formidable high over western Europe and the Atlantic together with a low in the north are sending moist air masses from the Atlantic in the northwest towards the Alps. These air masses are, in turn, bringing intensive precipitation. According to meteorologists, it now appears likely that this pattern will persist over the next few weeks and bring more fronts our way.

Initially, no significant relaxation of the situation is in view.

Stormy, snowy days – high avalanche danger in places

End of 2018 / Beginning of 2019: Stormy and Snowy

The start of the new year is storm-ridden (windspeeds of 180 km/hr in the southern Ötztal Alps) throughout Tirol, and there is lots of fresh snow in many places. In coming days the ZAMG weather service forecasts additional, at times very heavy snowfall, with the focal point east of Wipp Valley and northern East Tirol.

Illustrative of last week: the Hahnenkamm-Ehrenbachhöhe weather station in the Kitzbühel Alps. Weather deterioration starting on 30.12 amidst precipitation and wind.

Southern East Tirol ended up with practically no snow.

Snow plumes showcased wide-ranging snow transport throughout the land, as here in the northern Stubai Alps.  (photo: 01.01.2019)

Matrei Tauernhaus in the Venediger range during heavy snowfall and stormy winds. The stark gradients of snow depths towards the south are interesting. While here at the southern portal of the Felbertauern there was 40 cm of fresh snow on 01.01/02.01, in Matrei in East Tirol there was barely 5 cm.  (photo: 02.01.2019)

Extremely interesting,  quite seldom: the snow balls formed by the storm-strength winds in the free spaces in Kals (also behind the church).  (photo: 31.12.2018)

Snowpack development

A precise-as-possible depiction of snowpack layering is crucial before intensive precipitation. Currently the problem areas inside the snowpack are concentrated on the layers nearest to the upper surface. More deeply embedded graupel can also play an important role.

Yesterday on 02.01 during the snowfall: a thick layer of graupel was deposited in some places; this is now a potential weak layer for coming rounds of snowfall. Graupel was observed throughout Tirol. Kaiserbachtal  (photo: 02.01.2019)

Furthermore, covered powder snow is a temporary weak layer for the drifted masses which have been deposited on top of it. This can frequently be observed during intensive snowfall when temperatures are low.

Superficial slab on a gliding snowpack, recognizable by the glide cracks. Ausserfern  (photo: 29.12.2018)

The old-snow problem in the central sections of the snowpack referred to repeatedly in the most recent blogs seems in the interim to have shrunk to relatively narrow aspects and altitude bands. It is focused on the inneralpine regions, such as central East Tirol, where we assume potential problem zones on south-facing slopes between about 2400 and 2600 m and on north-facing slopes between about 2200 and 2600 m (in some places up to 2800 m). These zones are not usually cohesively connected over widespread areas.

A backcountry skier was ascending when an avalanche was triggered. The person remained unhurt. Gaishörndl, Villgratental.  Limited-terrain old-snow problem  (photo: 01.01.2019)

The snowpack’s proneness to triggering has diminished in these areas due to the temperature development, including warm phases. Nevertheless, we still have to expect these layers to fracture, at very least in the regions where precipitation has been heaviest. Deep persistent weak layers which formed on north-facing slopes on glaciers in autumn, can in all likelihood now be triggered only in highly unusual cases, i.e. through the additional loading of an avalanche which forms at altitudes above them in those regions where snowfall has been heaviest.

Typical of recent days: highly fluctuating temperatures. This was particularly striking in the northern regions, where  there was drizzling rain as far up as 2200 m for a brief interim.

The snowpack over the course of this last week was moistened on the surface: unbonded-snow avalanches on 27.12.2018 near the Pleisenspitze in the Karwendel. All in all, it had a positive impact on snowpack stability.  (photo: 28.12.2018)

Outlook

The ZAMG weather forecasting institute has issued a heavy snowfall warning for the morning of 04.01 until 07.01.2019, with more than 100 cm of fresh snow expected from region to region.

Eastern regions got the brunt of the snowfall.

Avalanche danger is increasing to high in the indicated regions. We expect increasingly frequent naturally triggered avalanches, particularly on leeward, very steep slopes adjacent to ridgelines and below rocky zones. The avalanches can easily reach large size (sizes 3-5) and even very large size (sizes 4-5).

Detailed forecast for the Venediger range: ongoing snowfall and continuing strong-velocity winds.

Already yesterday (02.01) and again today (03.01) several large-sized avalanches were triggered. Such releases occurred frequently in the regions along the eastern sector of the Main Alpine Ridge.

Naturally triggered avalanche in the Zillergrund. Further avalanches can be expected during the coming days in these regions, particularly where snowfall is heaviest.  (photo: 03.01.2019)

One thing is certain: during the next few days, massive traffic jams are on the agenda.

In the end, we appeal to all backcountry skiers and freeriders: whoever is en route in outlying terrain needs profound knowledge of avalanche risks and should behave highly defensively. We advise the inexperienced to remain on the secured and marked ski runs over the coming days.

From region to region, there is still a lot more snowfall on the way...Lampsenspitze. Northern Stubai Alps  (photo: 03.01.2019)