January 3, 2014 Avalanche Advisory
On slopes that are 35 degrees and steeper and wind-loaded, the avalanche danger in the west central Montana backcountry is CONSIDERABLE. Also, steep slopes above 7000 feet are holding weak snow layers that could fail with a human trigger or a new load of snow. Good decision making and route-finding are keys to safe skiing, sledding and riding.
Good Morning, this is Dudley Improta with the West Central Montana avalanche advisory for January 3, 2014. This danger rating does not apply to operating ski areas and expires at midnight tonight. (Jan. 3).
Weather and Snowpack Analysis
This morning westerly mountain winds are blowing up to 40 mph. The Point 6 weather station is showing gusts to nearly 60 mph. Mountain temperatures are warm in the upper twenties and low thirties. Much of the snow predicted came in as rain; snow levels will lower and taper off today.
With the winds and snow today, expect the likelihood of a human triggered wind-slab. Do not forget about side-loading in couloirs and gullies.
A secondary avalanche problem is the facets and weak layers near the bottom of the pack at elevations above 7000 feet. Reports and observations from Lost Trail, the Rattlesnakes, the northern Bitterroots, the central Bitterroots and the southern Swans indicated failures with snow tests 50 to 75cm from the surface on loose facets (Rattlesnakes Profile) (Northern Bitterroots Profile). I wrote Tuesday I didn’t trust these lower weak layers; this video shows why.You’re going to have to dig to see if these weak layers are present. This is a classic low probability / high consequence situation. These layers take a lot of force to fail in a test but when they fail we’re seeing propagation. I would look for them if sledding, skiing or riding a steep slope above 7000 feet; particularly near rocks or rock outcrops.
Weather Forecast and Avalanche Outlook
The snow and winds should diminish this evening. Cold air is expected to settle in. The colder temperatures may allow conditions for slab avalanches to persist. I’d keep the avalanche radar up all weekend.
Ski, sled and ride safe! Have a great weekend.
Steve will issue the next advisory on January 6, 2014.