Look for cold dry snow on north facing terrain at upper elevations. Be wary as this may also be where wind slabs develop.
Gusty winds will impact dry snow building slabs in lee features. Slabs are likely to be most reactive in areas below ridges or steep and unsupported features.
Rain and spring temperatures will warm the snowpack at lower elevations. Be mindful that that any solar input at upper elevations could encourage slab properties to rapidly develop in the new snow.
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.
