Avalanche Forecast

Moderate

• We are confident that there are persistent slabs in the snowpack, but uncertain about how likely they are to trigger.

In the last week of March, a couple of natural wind slabs, size 2-2.5 were observed on north and east aspects in the alpine. Natural cornice falls have been large enough that, even without triggering a slab, were size 2.5 or greater.

Persistent slab activity has tapered in the last week, but at least four occurred in the last ten days of March. Some are suspected to have run on the mid-March layer, and others even deeper. Most of these avalanches were triggered by cornices.

Roughly 5 to 25 cm of new snow fell Friday through Saturday, unfortunately mostly north of Bear Pass. It buried or combined with wind slabs and wind-affected surfaces in exposed areas and adds to about 15 cm of new snow in sheltered areas.

Collectively, the new snow overlies sun crust on solar aspects or on up to 40 cm of faceted snow in shelter. At least one operator near Terrace observed 6 mm surface hoar at the new snow interface, buried March 2.

A layer of facets and/or surface hoar from earlier in March can be found 50 to 100 cm deep.

Several older persistent weak layers are buried up to 250 cm deep. While triggering these layers is becoming unlikely, they present a low-probability, high-consequence problem.

Saturday night
Cloudy with easing flurries and a final 1 to 2 cm of new snow. 15 km/h southeast ridgetop wind. Treeline temperature -3 °C.

Sunday
Mostly cloudy with scattered flurries beginning late afternoon, 1 to 2 cm accumulation. 15 to 30 km/h southeast ridgetop wind, increasing. Treeline temperature approaching 0 °C as freezing level climbs to 1300 m.

Monday
Mostly cloudy with flurries continuing from overnight bringing 10 to 20 total cm of new snow to the alpine, diminishing with elevation to mostly rain below 900 to 1100 m. 30 to 40 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level falling from 1300 m to 900 m between about midnight and 06:00, after the bulk of precipitation falls.

Tuesday
Mostly cloudy with diminishing flurries bringing about 10 cm of new snow, mostly overnight. 15 to 40 km/h northwest ridgetop wind, easing. Treeline high temperature -2 °C. Freezing level 1100 m.

More details can be found in the Mountain Weather Forecast.

• Watch for newly formed and reactive wind slabs as you transition into wind-affected terrain.
• Be aware of the potential for large, destructive avalanches due to deeply buried weak layers.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
• Pay attention to cornices and give them a wide berth when traveling on or below ridges.