Following frequently intensive rainfall with numerous, mostly medium-sized avalanches and flooding in the Lower Inn Valley, ZAMG Weather Service now announces a cold front which will bring impressive amounts of fresh snow and storm-strength winds in the mountains.
 |
| The cold front will reach Tirol tomorrow, 4 February, accompanied by strong winds. It will bring impressive amounts of fresh snow by Wednesday, 5 February, as much as 100 cm from place to place. |
What’s most important in this connection is the point of departure for the snowfall, which is not all that bad. The previous rainfall weakened the snowpack tremendously. Weak layers inside the snow cover are thus only isolated and even then, found only at high altitude.
Main problem: snowdrifts at high altitude and wet-snow at low/intermediate altitude
One of the major problems with the approaching snowfall lies inside the masses of fresh snow. Layers of graupel from place to place are potentially weak layers. Also varying wind impact during the snowfall leads to varying hardnesses inside the snow masses. A comparatively soft layer of fresh snow full of concavities could be a weak layer for the snowdrifts which are deposited on top of it.
In addition, the wet old snowpack is still prone to triggering in places. This applies especially to extremely steep terrain in the regions where fresh snow is scarce, where the impulse of a skier or freerider could well trigger a wet loose-snow avalanche to release. Also glide-snow avalanches remain a danger which cannot be underestimated, particularly in the regions of Tirol where snowfall is heaviest and where it rained intensively in the last few days.
Think about this: fresh snow which starts to move can also sweep the wet snowpack along with it. Since the snow depths are below average at low and intermediate altitudes throughout the land, the runout zones of such avalanches will remain somewhat limited.
Winter sports enthusiasts, beware!
Heed the threats of snowdrifts and wet snow over the next few days.
Avoid fresh snowdrift masses in very steep terrain for the next few days. The spread and the trigger-sensitivity of freshly generated snowdrift accumulations tend to increase with ascending altitude.
We advise the inexperienced not to leave secured ski runs.
A glance back: lots of rainfall in northern regions
The forecasts of ZAMG Weather Service have arrived. In wide ranging parts of Tirol there was intensive rainfall on 2-3 February, focal point was in the northern regions. The rainfall level generally lay between 2300 and 2500 m. On 3 February it descended to about 2000 m.
 |
| Distribution of precipitation in Tirol over the last 24 hours |
 |
| Maximum measured precipitation was over 90 mm. |
Snowpack is wet up to high altitudes. Naturally triggered avalanches.
The rain made the snowpack thoroughly wet up to high altitudes, even more so in regions where precipitation was heavy. Thus, the snowpack completely forfeited its firmness. The upshot: numerous naturally triggered avalanches. These were usually wet loosely-packed avalanches and glide-snow avalanches. To an increasing degree they were Magnitude 2, in some cases Magnitude 3, as well as many slides. Naturally triggered slab avalanches were also reported. These fractured above the rainfall level, particularly in northern regions.
Here is a selection of photos of recent avalanche activity in Tirol:
 |
| A mixture of wet loose-snow and glide-snow avalanches in Lechtal. (photo: 03.02.2020) |
 |
| Numerous small loose-snow avalanches in Stubaital. (photo: 03.02.2020) |
 |
| Avalanche below a waterfall which was climbed by ice climbers yesterday, in Sellraintal. (photo: 03.02.2020) |
 |
| Heightened glide-snow activity, here below Seegrube near Innsbruck. A released glide-snow avalanche. More gliding activity is already in motion (see arrows). (photo: 03.02.2020) |
 |
| Some avalanches even reached closed ski runs, as here in Rettenbachtal in the Ötztal Alps. (photo: 03.02.2020) |
 |
| The avalanche visible in background was triggered artificially with explosives. (photo: 03.02.2020) |
 |
| Little impulse, big effect: wet loose-snow avalanches grew to large size in some cases. Obergurgl. (photo: 03.02.2020) |
