Started by Admin in Avalanche Safety 12-Jan-2012
For the full bulletin - go here - but here are the salient points :-
On Wednesday it was sunny. The midday temperatures at 2000 m were plus 3 degrees in northern regions and plus 5 degrees in southern regions. The northerly wind was blowing at moderate velocity on the Main Alpine Ridge and in the Engadine, elsewhere it was predominantly light.
The deep layers of snow from the most recent periods of precipitation have settled and consolidated well. In some places, layers of snowdrift near the surface are still trigger sensitive. Particularly on the Main Alpine Ridge and in the Engadine on shady slopes above 2500 m, the snowpack layers nearest to the ground are faceted and weakly bonded. In those places more than anywhere else, isolated avalanches can fracture deep in the old snowpack. Due to the deep snowpack far and wide, many full depth snowslides released below about 2500 m.
See the video Bandit posted earlier this week of the Avalanche crossing a piste at Les Crosets
On Thursday, following a night of clear skies, it will be sunny. The midday temperature at 2000 m will be plus 3 to plus 5 degrees. The northwesterly wind will be blowing at light to moderate velocity during the morning, intensifying to moderate to strong velocity in the afternoon.
Avalanche danger forecast for Thursday
Zervreila; Rheinwald; Avers; Bivio; Engadine south of the Inn:
Considerable avalanche danger (Level 3)
The avalanche prone locations are to be found primarily on wind loaded slopes in all aspects above approximately 2400 m. More recently formed snowdrift accumulations can be triggered by a single backcountry skier or freerider in some places. Over the course of the day on steep, sunny slopes, the proneness to triggering will escalate. In addition, fractures in the old snowpack, which is weak, are possible, primarily through large additional loading, on shady slopes above approximately 2500 m in particular. In transition areas from shallow to deep snow, caution is essential.
Northern flank of the Alps; Valais; northern and central Ticino; northern Grisons; central Grisons not including the regions Zervreila, Rheinwald, Avers, Bivio; in addition, Engadine north of the Inn; southern valleys of Grisons:
Moderate avalanche danger (Level 2)
The avalanche prone locations are to be found on steep slopes in all aspects above approximately 2000 m. More recent snowdrift accumulations can be triggered particularly through large additional loading, such as a group of backcountry skiers of freeriders. During the course of the day, the trigger sensitivity on steep, sunny slopes is expected to rise. In addition, on the Main Alpine Ridge fractures in the old snowpack are possible in isolated cases.
In all regions of the Swiss Alps, full depth snowslides which may attain medium size can be expected at any and all times below approximately 2500 m. This applies in particular on steep, grassy slopes and road embankments in eastern, southern and western aspects. Exposed sectors of transportation routes can be placed at risk. Caution is urged below glide cracks.