Wet avalanches or wet slab avalanches were occurring throughout the West Central Mountains yesterday as the rain line crept up towards 8000 feet. Wind loaded slopes and heavily corniced ridgelines had already released and steep slopes from close to the valley floor up to nearly 8000 ft. were shedding snow. On steep slopes where the melt freeze crust from early last week was present we were able to easily trigger wet, slablike avalanches with ski cuts. In the upper elevations, the slightly cooler snow was more cohesive and more slablike. In the lower elevations, roller balls and loose/wet slides were prevalent.
Temperatures dropped early this morning into the upper 20's around 6500 feet and will begin to refreeze the snowpack from the top down, but this is going to take a little time to stabilize the snowpack. Expect the instabilities to persist through today especially in the mid to lower elevations where it is going to take longer to refreeze. As the snowpack cools back down over the next couple of days, expect stability to improve.
Rain on snow events create unusual conditions and extra caution should be taken to avoid exposure on or near slopes steep enough to slide. These are the kind of events that create large, destructive avalanches in steep canyons, gullies, confined avalanche paths and other lower elevation terrain.
Local Snotel sites picked up quite a bit of moisture over the last 24 hours. With day time temperatures in the high 30's yesterday that moisture was nearly all rain. Secesh Summit picked up just about .75 inches of Snow Water Equivalent yesterday with Brundage Reservoir topping 1 inch. Winds were also gusting yesterday and last night and probably made for some more weird conditions in the heavy, wet snow that was falling in the upper elevations.
We toured up Lick Creek canyon to Hum Saddle yesterday and saw some debris on steep, avalanche prone terrain in the morning as we sledded up towards the Duck Lake trail head. We found a saturated snowpack that was loosing cohesiveness and some challenging ski conditions. Throughout the day the visibility gave us glimpse of slopes that were littered with fresh, loose, wet avalanche debris and some older debris from earlier in the week on wind loaded slopes. Pit tests showed easy initiation of the wet slab above last week's melt freeze crust but a general lack of propagation in the wet slab. On our way down canyon, most of the big slide paths had wet debris in them although visibility was poor and still didn't give us a clear picture of size.
Also, having seen older debris on Northerly slopes near Hum Lake, we were reminded of the natural cycle that occurred last Sunday. Skiers reported triggering 10-12 inch soft slab avalanches that propagated easily on a layer above the crust. Natural, shallow avalanches release on many northerly aspects. Tuesday, we received a second hand report of a skier that was partially buried in the Lick Creek Canyon but no further information about that incident.
If you are involved in an incident in the West Central Mountains or anywhere in the West. PLEASE, take the time to share incidents and your observations on the PAC or your local avalanche center website. You can fill out an observation and remain anonymous if you choose. There are several questions and easy to fill out fields to describe what you saw or what occurred. Gathering this information helps not only the local avalanche center and its audience but the incident information gets logged in a national database and studied to help snow scientists gather more knowledge about the human and environmental factors as well as the decision making processes that contribute to avalanche accidents and incidents.
|0600 temperature:||19 deg. F.|
|Max. temperature in the last 24 hours:||32 deg. F.|
|Average wind direction during the last 24 hours:||SW|
|Average wind speed during the last 24 hours:||7 mph|
|Maximum wind gust in the last 24 hours:||31 mph|
|New snowfall in the last 24 hours:||4 inches|
|Total snow depth:||60 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.