The winter just doesn’t want to stop...
Over the last few days, a strong southerly foehn wind was blowing in the mountains. Today (11.05) the foehn collapsed. In the southern regions, precipitation has set in. In the northern regions a cold front from the west will move in during the evening/nighttime hours.
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| Windspeeds reach nearly 150 km/hr on Patscherkofel |
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| Map of precipitation 11.05, 15:00 h. In southern regions, precipitation has already set in. Hot spot currently: Timmelsjoch. |
Rainfall was initially expected up to about 2500 m. The snowfall level will settle at about 1500 and 2000 m as a result of the cold front (lower in the north than in the south).
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| 48-hr forecast of fresh snow |
Avalanche danger rising
A bit of fresh snow, together with wind impact, will increase avalanche danger. We expect large-sized naturally triggered releases in high alpine regions where there was lots of snowfall. This forecast is based on current reports of a large-sized near-surface slab avalanche near the eastern Simonyspitze in the Venediger Massif, as well as our own considerations.
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| Naturally triggered avalanche on eastern Simonyspitze (photo: 09.05.2021) |
We currently assume that in high alpine regions a near-surface weak layer has formed due to Danger Pattern “cold-on-warm” (dp.4). With appropriate additional loading from the fresh snow it can be expected that slabs can trigger naturally, including over larger surfaces. In addition, fresh snowdrift accumulations at high altitudes can be triggered for a brief period by winter sports enthusiasts (weak layer, possibly blanketed powder or graupel). Increasingly. such danger spots are found near ridgelines in very steep terrain.
Abruptly activated fresh snow, due to diffuse solar radiation
Fresh snow at this juncture of the season reacts extremely rapidly to warmth and solar radiation. On Thursday at latest, when clouds will begin to disperse from place to place, we expect swift loss of firmness of the fresh snow. On the one hand, due to the sudden impulse of warmth; but also through naturally triggered slab avalanches. Loosely-packed snow and slab-avalanches can, subsequently, even sweep along the entire thoroughly wet snowpack with them in their plummet path.
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| Naturally triggered slab avalanches from 10 May due to increasing wetness of the snowpack on shady slopes. Altitude: 2500 m. |
Restraint. And experience.
Thus, we anticipate a situation in which winter sports enthusiasts have gathered ample experience, where defensive strategy is called for. In addition, caution below the starting zones and in steep avalanche prone areas near canalised avalanche plummet paths is urged. There, avalanches can plummet down to low altitudes and even endanger hiking trails and forest roads.
