Tag Archives: snow observations

Feb 24 , 2011 Snow Obs

Winds have capped up the ridge lines, but softer, less wind effected snow exists 150′ below these ridge lines. Good skiing can be found, but you will have to look a little harder.

Avalanche activity has diminished, but continues to linger. This weeks’ avalanche activity ripped on the new/old snow interface. This was exacerbated due to an inversion in snow hardness. The beginning of the storm was lighter, fluffier snow, followed by heavier snow and some added wind effect. You can see this easily in hand tests. The rapid loading [storm] with an unstable structure [inversion] produced many avalanches within the first 24 hours of the storm.

Now that the snow pack has had some time to adjust and some of that weight has vaporized into the atmosphere, we are seeing less avalanche activity. I observed NO new natural avalanches, but I did observe two new human triggered avalanches. Both of these crowns are located at rock outcrops that have weaker snow structure than the less rocky snow slopes. I would take this as a good clue and stay away from rocky bands and known rocky bed surfaces [facet gardens].

Here is a good image depicting the current hazard:

feb 24 2011

feb 24 2011

The yellow outlines avalanches from Feb 19th.

The red outlines a new human triggered avalanche from yesterday? today? [HS-ASu-R2D2-I] that started at the rock outcrop, ran ~100′, then stepped down below some of the hard slab and crust layers and ran another 700-800′. You can see the snowboard tracks exiting the starting zone.

The blue tracks show some boarders or skiers that did not trigger avalanches from todayish.

The green is a snowmobile track that impressively did not trigger an avalanche.

What we can quickly determine from this photo is that while the hazard has lowered significantly from the19th, we still have obvious human triggered avalanche potential. I observed no new natural avalanches anywhere today. And although the potential is there for human triggered avys, it is obvious that you will not trigger them everywhere or always. Another good observation is that the avalanches have been, for the most part, triggered near rocky outcrops and rock bands. So stay away from those. Also stay clear of slopes that have known rocky bed surfaces for an added safety margin.

Notice that weak points in the snow pack are variable and therefore hard to predict where avalanches will occur. It is also likely that one snow stability pit may yield agreeable results, while another one next door may not. So.., while the avalanche hazard is moderate, know that the potential is there and that the consequences can be severe given the size of the human triggered avalanches we have seen.