The mountains of the Kootenai National Forest received a light dusting of new snow that is sitting on the rain crust that developed during the rains of March 18th. More snow is called for in the mountain weather forecast this weekend. This new snow will likely begin to slide off in slow moving wet slides on warm sunny days.
Spring is here, and with it come the standard set of fairly predictable avalanche problems. The mountains of the Kootenai have undergone multiple freeze thaw cycles and rain events that have bridged and reduced the weak layers within the snowpack. Generally we are dealing with very stable snow. This scenario can change on any given day when the sun comes out, the temperatures rise or the rain falls. Rising temperatures may result in small, benign wet slides to large climax avalanches on deep weak layers. Staying safe will be a simple matter of paying attention to the weather and snow conditions before jumping into steep terrain.
On March 23rd we travelled into the Pete Creek area to monitor the deeper instabilities that we have been tracking through the winter. The weak layers deep at the ground are dissipating due to the heavy rains and warm spring temperatures. We observed the remnants of multiple slides that likely released during Saturdays rain event. There was 5" of fresh snow on top of a 4" thick rain crust. Weaknesses within the snowpack are unlikely to be triggered by snowmobilers or skiers; however, as I mentioned in the discussion this could change with any rising temperatures, rain or intense sun.
Backcountry Forecast from NWS Missoula issued:
210 PM MDT Thu Mar 23 2017
DISCUSSION: A ridge of high pressure will dominate the region
today through much of Friday. By Friday afternoon another weather
disturbance will move through the region impacting the region with
precipitation through Saturday morning. A couple of inches of snow
are expected with snow levels lowering to 4000-4500 feet. Some
higher elevations may receive up to 6 inches of snow.
--------------------------- 5000-7000 FT ----------------------------
Tonight Fri Fri Night Sat
Cloud Cover 60% 90% 90% 95%
Hi/Lo Temps 20 to 25 33 to 41 25 to 31 33 to 41
Winds(mph) S 8 S 11G24 SW 14G29 SW 10
Precip Chc 0 90 90 60
Precip Type none sno/shr sno/shr sno/shr
Liquid Amt 0.00 0.17 0.19 0.10
Snow Amt(in) 0 1-2 2-3 1-2
Snow Level 3500 3000 4000 4000
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 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.