Avalanche Forecast

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack. Uncertainty is due to the track & intensity of the incoming weather system.

TUESDAY NIGHT: Flurries and snow, 10-15 cm by morning and rain at lower elevations. Moderate southwest wind increasing though the night, alpine low -12C, and freezing level hovering around 1000 m.

WEDNESDAY: Ongoing flurries, accumulating 15-20 cm by the end of day. Moderate southwest wind decreasing though the day, alpine high 0C, and rising above 1500 m.

THURSDAY: Unsettled with isolated flurries and sunny breaks. Light west wind, alpine high -1C, and freezing level above 1600 m.

FRIDAY: Unsettled flurries, little accumulation. Moderate northwest wind, alpine high +2C, and freezing level rising above 1800 m.

On Monday, a few natural storm slab avalanches to size 2 were observed in the alpine, likely failing overnight and numerous loose dry avalanches to size 2 were reported as well. Skiers triggered size 1-1.5 storm slab avalanches 20-50 cm deep on south and east aspects above 2000m, and a couple of cross-loaded convexities in open treeline. Explosives triggered several size 1-1.5 avalanches on NW-N-NE aspects above 1800 m. A large (size 2) natural cornice failure occurred overnight, entraining the storm snow but not pulling a slab below. And several natural storm slab avalanches size 2-2.5 were reported in Glacier NP, occurring on north-northwesterly aspects above 1950m.

On Sunday, explosives and skier traffic triggered numerous size 1 avalanches, new and touchy cornices were observed. A few small dry loose avalanches and sluffing in steep terrain was also reported.

On Saturday, explosives triggered small (size 1-1.5) storm slabs from north-northeast aspects above 2000 m. A skier also triggered a small (size 1) wind slab on a steep convex roll on an easterly aspect at treeline. Sluffing was reported in steep terrain. In Glacier NP, a handful of storm slabs size 1.5-2.5 released naturally from steep north-northwest aspects above 2000m.

On Friday, several glide slab avalanches (size 2-3) were observed on south and east aspects around the TCH highway corridor. Loose wet avalanches up to size 2.5 were reported around the region; a natural loose-wet cycle was reported around Rogers Pass initiating with evening rainfall.

Southwesterly winds and flurries will form fresh slabs in lee features. 20-40 cm (up to 60 cm in areas) recent snow covers dry and compacted snow on polar surfaces above 1800 m and crusts on solar slopes; storm snow has been sluffing easily on the crust. In some areas of the region, surface hoar (4-10 mm) has been reported below the recent storm snow in shaded north-facing slopes at upper treeline and above. Large cornices loom over alpine ridgetops. Spring temperatures and sun are producing a melt-freeze snowpack below 1500 m and higher on solar slopes.

Persistent weak layers of surface hoar, crusts, and/or facets 80-120 cm down have recently been unreactive and no recent avalanches have been reported on these layers. 

• Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
• Carefully evaluate steep lines for wind slabs.
• Pay attention to cornices and give them a wide berth when traveling on or below ridges.
• Brief periods of sun could quickly initiate natural avalanche activity.
• Back off slopes as the surface becomes moist or wet with rising temperatures.