Good morning backcountry travelers. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Saturday, April 23th at 7am. We are no longer issuing daily avalanche advisories for 2010-2011 season however, this does not mean that the avalanche season is finished. See below for an update for the Turnagain Arm area (this does not apply to highways, railroads, or operating ski areas).
As of 6am Saturday morning rain is falling below around 1500′. There has been 2-4” of snow at 1800′ in Turnagain Pass and 10-14” at 1700′ in the Girdwood Valley. Higher amounts are expected at upper elevations. The east winds are on overdrive with gusts in the past 24 hours of 60-70mph on the ridgelines.
The main issues for the April 23rd and 24th weekend will be wet snow avalanches at mid and lower elevations and storm snow and wind slab avalanches at upper elevations. These are LIKELY to release both on their own as well as being triggered by a person.
Advanced route finding skills will be necessary if traveling in the backcountry over the weekend. This includes steering clear of avalanche run out zones and wind loaded terrain. Even while out hiking, run out zones with no snow at your location can be dangerous because there may be snow above you that could slide at any time.
Wet snow concerns:
At lower and mid elevations any rain on an already isCNFAIC Staffmal snowpack (see photo gallery) will increase wet slab, or wet loose, avalanche activity. Wet avalanches in general entrain very dense and heavy snow, run far and are hard to escape from. They can push you into trees, over cliffs and into gullies. The KEY clue to watch for is when the snow becomes so soft and slushy your boot sinks below the ankle. This is often in the afternoon as direct sun warms the snow, but can be any time of day this weekend with the rain on snow and warm temperatures that have kept much of the snow from refreezing.
Dry snow and new snow concerns:
New snow and wind at upper elevations, and some middle elevations, should see widespread wind drifting. Human triggered soft slab and wind slab avalanches will be likely in areas receiving several inches of new snow. Keep an eye out for recent avalanches, as well as cracking and collapsing, on and off ridgelines, rollovers and cross-loaded gullies. The minute the sun pokes out and hits the new snow (may not be till Monday) wet loose natural and human triggered avalanches will be likely.
With snow, rain and wind continuing over the mountains, visibility is likely to be limited today as well as on Sunday. Wet saturated snow lies below around 2000′, possibly higher, and heavy dense snow below around 3500′. Amounts are unknown at higher elevations but could be in the 8-12” range for Saturday and anCNFAIC Staff 4-10” on Sunday with local variations. The rain/snow line should hover near 2000′ today and lower to near 1000′ for Sunday. Right now it looks as though partial clearing by Monday.
Remember – Stay tuned for periodic updates through April 30th.
Thanks for checking the avalanche advisories this season. Have a great spring and summer!