Turnagain Pass

With limited visibility we have little information as to avalanche activity over the past couple days of warm stormy weather.

The second wave in a series of warm storms moved in early this morning. Since midnight, almost an inch of rain has fallen in the Girdwood Valley, close to 3″ in Portage Valley and 0.4″ at Turnagain Pass. The rain/snow line looks to be somewhere between 2,500 and 3,000′. Ridgetop winds also bumped up this morning into the 20-30mph range with gusts near 60 from the east.

With such rainy weather we can expect some naturally occurring wet snow avalanches to be taking place on steep slopes and gullies. These are most likely happening in the Portage Valley, but they are also possible in the Girdwood Valley, Turnagain, down toward Seward, and anywhere rain is falling snow. If a person was to be out on a steep slope in these mushy conditions, chances are it would be easy to initiate a wet loose avalanche that could run far if the slope is long enough. Avoiding steep slopes and small steep terrain features is recommended today. Even a small wet avalanche can be quite hard to manage if it pushes us into a tree well or depression.

Rainfall numbers for today. Graphic courtesy of the National Weather Service Anchorage Office. You can find this and the rest of their ‘Avalanche Weather” HERE. 

A break in cloud cover during the break is storms yesterday seen from the Seattle Ridge weather station. Unfortunately, rain has made it to this station that sits at 2,400′ in elevation and looks to the south over Turnagain Pass.

At the upper reaches of our forecast zone (above ~3000′ or even 3,500′) winds are gusting 40-60mph from the east. At these ridgetop elevations there should be dry enough snow that newly formed wind slabs may release on their own. Not to mention being easily triggered by a human. In the right terrain, debris from a wind slab avalanche can run into wet snow and cause a wet snow avalanche, combining to produce an even larger avalanche. We see this during events similar to this one in the large avalanche paths.

Old weak layers? It’s also worth mentioning that in the high terrain there were two weak layers that we are monitoring. Weak facets near the ground above 3,500′ and buried surface hoar around a foot deep as of last week. There are a lot of unknowns with these. This storm may help to flush them out, but we will still be looking for signs they could produce avalanche down the road.

Glide avalanches were occurring during the cold snap last week, and may be on the rise again with the warm conditions. Once skies clear enough to get a look around, we’ll be watching for any new glide activity.