Northwest Inland

A layer of buried surface hoar is increasing reactivity and propagation in wind loaded features.

Watch for changing conditions as you move through aspect and elevation bands.

Slab avalanches have been reported over the week, naturally and rider triggered.

Of note: a size 3 (very large) naturally triggered deep persistent slab avalanche was reported in the Stikine area, on a south facing slope at 1300 m. This avalanche occurred on the basal facets, up to 250 cm deep, likely triggered by a combination of warm temperatures and sun effect. This is the only recent avalanche on this layer. Triggering is considered most likely during periods of rapid change to the snowpack. Several recent cornices failures were also noted throughout this region, entraining snow on the slopes below but not triggering a slab avalanche. In the right terrain cornice falls may be large enough to produce an avalanche on the deep persistent weak layer.

Wind slabs, around 25 cm deep have occurred primarily at higher elevations on north facing terrain features to size 2, including a remotely triggered size 1 Loose wet avalanche activity was noted on sun affected and low elevation terrain to size 1.

Southwest winds have created reactive deposits on north to east facing terrain features near ridges. A melt freeze crust or moist snow exists on the surface at low elevations and on sun affected slopes into the alpine.

10-25 cm overlies large surface hoar crystals in terrain sheltered from the wind and sun, wind-affected snow in wind exposed terrain, and a hard melt-freeze crust on sun-affected slopes.

The middle of the snowpack is strong and contains numerous hard crusts.

The lower snowpack is composed of weak basal facets. This layer has produced limited recent avalanche activity, however it can quickly become active again with any significant change to the snowpack, such as rapid loading (heavy snowfall or rain) or prolonged and extensive warming. Avoiding thin and rocky slopes is still recommended. Cornices are also very large and a cornice failure could trigger this basal layer.

Saturday Night

Mix of clear skies and cloud. Freezing levels 1500-1000 m.

Sunday

Mostly cloudy with up to 2 cm of snow. Strong southeast winds. Freezing levels rise to 1500 m. Alpine temperatures around -4 °C.

Monday

Cloudy skies and moderate to strong southeasterly winds. Freezing levels rise to 1500 m. Alpine temperatures around -4 °C.

Tuesday

Mostly cloudy. Freezing levels rise to 1500 m. Alpine temperatures around -4 °C.

More details can be found in the Mountain Weather Forecast.

• Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
• Pay attention to cornices and give them a wide berth when traveling on or below ridges.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
• Minimize exposure to sun-exposed slopes when the solar radiation is strong.