Breaking news: Big daytime rise in risks today (28.01.21). High avalanche danger.
A warm front from the Atlantic has been generating our weather conditions since yesterday (27.01) and, consequently, also our avalanche conditions. Most of the precipitation is anticipated in the western, also in the northern regions of North Tirol. ZAMG Weather Service forecasts 40-60 cm of fresh snow for today in the main areas of precipitation, more from place to place. Accompanying the precipitation will be a continual rise in temperatures plus increasingly stormy winds.
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| 72-hr snowfall forecast since 27.01. 07:00 am |
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| Wind forecast for today, 28.01. 4:00 pm - Storm in the mountains. |
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Current conditions measured at Jamtal Refuge, Silvretta: snowfall amid rising temperatures.
The fresh snow is dry, fell at low temperatures in many places. |
This combination, coupled to the current snowpack layering, guarantees numerous naturally triggered slab avalanches. For that reason, we have classified today’s danger in most parts of North Tirol as high, seen through the lens of a daytime cycle.
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| Danger-level map for 28.01.2021 - Hour-by-hour increase in danger. |
In addition, as a result of rising temperatures, together with rain, increasingly frequent glide-snow and wet-snow avalanches are expected to release. Exposed transportation routes are at risk.
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| Thoroughly moist snowpack and additional loading of fresh snow: that pushes snowpacks to just glide away over steep, smooth slopes, as here on a meadow. Defereggental (photo: 24.01.2021) |
A review, to make the current situation easily graspable
Short weather review
Last week was turbulent, highly variable. The southerly foehn was replaced on Friday night by a cold front (23.01). At that time, the focal point of the precipitation was, once again, the southern regions.
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| 72-hr difference in snow depths: 22.01.-25.01.2021 |
On Monday (25.01) moist, cold air masses brought snowfall from the northwest, focal point: northern barrier cloud zones.
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| 48-hr difference in snow depths: 25.01.-27.01.2021 |
And now, a warm front is heading our way which will be replaced by further cold-and-warm fronts (less intensive than the current front).
A glimpse inside the snowpackDecisive in the current situation is the loosely-packed, still cold powder on the snowpack surface. Due to today’s precipitation with rising temperatures and winds (28.01), the uppermost layers to an increasing extent will bond together. This will generate large-sized “slabs” which will bond extremely poorly with the cold powder snow on top. Subsequently, numerous naturally triggered slab avalanches will release in the loosely-packed powder. In many cases, the snowpack loading will initiate fractures down to other weak layers more deeply embedded in the snowpack. Avalanches in the major areas of precipitation can for that reason grow to very large size in some cases. What suggests the secondary fractures: recent stability tests conducted throughout the land. Fractures were frequently propagated, even by only medium loading. Therein lies one of the fundamental prerequisites of slab avalanches.
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Snowpack analysis on 27.01, Hafelekar, Northern Alps. The surface is loosely-packed in many zones. Inside the snowpack are softer, trigger-sensitive weak layers.
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Slide-Block Test during an Avalanche Commission course in Defereggental (c) LK Defereggen
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| A typical snapshot: loosely-packed surface snow, weak layer in the middle of the snowpack (of faceted crystals from the cold phase in mid-January). NE, 2120m |
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| A similar situation on sunny slopes: S, 2240m |
Avalanches during the recent week
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| Avalanche Poverer Jöchl on 22.01.2021 - Tux Alps. Large-spread weak layers from the cold phase |
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| Naturally triggered avalanches following snowfall as of 22.01. - south-facing - Deferegger mountains |
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| A similar picture to the previous one, Schober Massif (photo: 24.01.2021) |
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| Avalanche near a forest zone. Niederberg (photo: 25.01.2021) |
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| This naturally triggered slab avalanche developed a powder cloud. Glockner Massif (c) foto-webcam |
