At 6:00 pm the ZAMG Weather Service published a report about an extraordinary precipitation event for the period 2-3 February in Tirol.
As the result of a warm front, mild and extremely moist air masses are being transported to Tirol. Most of the precipitation is expected on the northern rim of the Alps: 60-90 mm of rain, focal point in the Allgäu Alps and Lechtal. In the Upper Inn Valley and eastern parts of the Lower Inn Valley, amounts of 30-60 mm are anticipated.
The rainfall level is expected to be at 2200-2500 m for this period.
Snowpack weakening, naturally triggered avalanches
Rain and warmth bring about a huge weakening of the snowpack. At low and intermediate altitudes we expect increasingly frequent wet loosely-packed and glide-snow avalanches. Due to the already moist and increasingly wet snowpack, even small impulses for wet loosely-packed avalanches lead to deeply embedded layers fracturing and being swept along. Increasingly, the less settled snowpack on W/NW to N to E/NE facing slopes is being drawn into this syndrome. Glide-snow avalanches are possible in all aspects.
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| At low and intermediate altitudes, esp. loosely-packed and glide-snow avalanches are expected. Tannheimertal (photo: 02.02.2020) |
Naturally triggered avalanches, on the other hand, are expected at altitudes above 2000 m in particular, and there, especially in W-N-E aspects. Again, terrain which has been little tracked until now is expected to be hit hardest.
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| Pictured is the slab avalanche released on 31 January on an untracked west-facing slope beneath Predigberg in the Silvretta, altitude 2200 m. One person was swept along for about 400 m by this avalanche. Similar naturally triggered avalanches can now be expected, due to rainfall and warmth. (photo: 31.01.2020) |
In addition, slab avalanches are possible in ridgeline wind-protected terrain at high altitudes. There, the graupel deposited on 1-2 February could constitute a weak layer.
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| Several factors play a role: 1) expansively metamorphosed layer from the long period of fine weather, even if snowpack analysis shows increasingly good bonding to nearby layers; 2) Bonding of the layers atop these due to warmth; 3) Snow temperature up to at least 2000 m is 0 degrees, thus, the snowpack swiftly becomes wet and forfeits its firmness. |
High avalanche danger in regions where rainfall is heavy
For more information, please see avalanche.report
Subsequently, a cold front will bring snow down to low lying areas. Then: a period of fine weather. Restraint is called for!
In the wake of the warm front, a cold front will bring snow down to 600 m and storm-strength winds in the mountains. The avalanche situation will remain tense for the coming period. As of Thursday, 6 February, high-pressure weather will prevail, according to the ZAMG Weather Service forecast.
Our recommendation: inexperienced winter sports enthusiasts should stick to the ski runs. All those who leave them and head into outlying terrain absolutely need extremely good avalanche knowledge.
