Strong winds and 16-21 inches of new snow have created a recipe for slab avalanches throughout the West Central Mountains over the last week. Winds have swirled around from the S to the NE during this time creating wind slabs on multiple aspects. The newest crop of wind slabs is in the 10-14 inch range with older wind slabs as deep as 2.5 feet possible. Some of these wind slabs from last week are now camouflaged by the addition of new snow above them. A layer of faceted snow developed in some areas prior to the last 8 days of storms and is resting on the stout crust deposited in late January allowing avalanches in these areas to propagate over larger areas. These slabs while widespread are not reactive in all areas, your best bet for triggering a shallow or deeper slab is going to be found on steep, NW, N and NE terrain. In addition, E and W aspects may be harboring isolated wind slabs on cross loaded slopes and smaller terrain features.
Winds are currently gusting out of the NE to near 20 mph and another significant storm will be entering the area beginning tonight. Pay attention to changing conditions, fluctuations in the temperature over the next few days and the addition of 16- 30 inches of new snow over the next 3 days.
Watch for signs of instability today and through the weekend including: recent avalanche activity, cracking, collapsing and whumphing in the snowpack. If you encounter these or signs of denser snow resting on the light snow below, stick to lower angle, less avalanche prone terrain.
See photos below for big wind features where North winds pushed snow up a gully into this pyramid feature on a flat ridge and cracking in the upper 14 inches of the snowpack on a small wind slab.
Loose, dry avalanches or sluffs are widespread right now on steep terrain. Our mountains have received between 16 and 21 inches of new, low density snow over the last 7 days. Widespread natural sluffing and point releases in the light density snow are visible on multiple aspects and on steep terrain at all elevations. While these small avalanches don't pack a lot of punch, they do have the ability to pile up in terrain traps or steer a skier where they don't want to go. Use good travel etiquette and keep your eyes on your partners. Avoid steep, confined and consequential terrain where a small sluff could create larger problems. Additional storm and wind deposited snow will continue to add to this problem over the next few days.
Please come out and support the FPAC tonight at the McCall Golf Course. Fundraiser and music starts at 7pm. Raffle throughout the evening. Also, PLEASE take the time to send us your observations of the snowpack or avalanche activity. Several incidents occurred this week and went unreported to the PAC. It's easy to do, it takes just a few minutes and it may save a life. Click on the send observations tab on the advisory page or on the main menu. See you at the Fundaiser tonight!
Yesterday we toured near Fisher Creek Saddle and found great, possibly the best skiing and riding conditions of the season. We also saw signs of widespread sluffing on steeper terrain and the remnants of natural avalanches that have occurred over the last week. Winds have been able to move the new snow around in some unusual ways over the last week creating not only a variety of wind slabs but some fairly large cornices, and wind spines in the upper elevation terrain. Pit tests in northerly, high elevation terrain showed 10-16 inches of very low density snow resting on a more dense layer which is resting on a decomposing crust. Above the crust is a layer of rounding but still loose and faceted snow that formed in some areas prior to last week's storms. This layer failed in both compression and propagation tests at an hard moderate or low considerable level.
Several natural and human triggered avalanches in the 2 foot range failed at this layer earlier in the week or on the crust below. The largest reported avalanche was in Wildwood Bowl just outside the north boundary of Tamarack Resort and prompted a beacon and dog search by Tamarack Ski Patrol after getting reports that it was skier triggered and witnesses hearing shouts for help. Also, our condolences and thoughts go out to the family of a snowmobiler from Idaho Falls that was killed Wednesday in eastern Idaho in an avalanche near Pallisades Falls.
|0600 temperature:||-2 deg. F.|
|Max. temperature in the last 24 hours:||21 deg. F.|
|Average wind direction during the last 24 hours:||N|
|Average wind speed during the last 24 hours:||5 mph|
|Maximum wind gust in the last 24 hours:||18 mph|
|New snowfall in the last 24 hours:||NA inches|
|Total snow depth:||73 inches|
This avalanche advisory is provided through a partnership between the Payette National Forest and the Payette Avalanche Center. This advisory covers the West Central Mountains between Hard Butte on the north and Council Mountain on the south. This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires at midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.