Avalanche Forecast

TUESDAY NIGHT: Flurries and snow, 15-20 cm accumulation expected by morning. Moderate to strong southwest wind, alpine low -6C, and freezing level hovering around 1000 m. 

WEDNESDAY: Snow and wet flurries, 5-15 cm with storm totals between 20-35 cm by the end of the day. Moderate and decreasing west-southwest wind, alpine high -1C, and freezing level hovering around 1000m overnight Tuesday and rising above 1500m during the day.

THURSDAY: Mostly cloudy and unsettled. Light southwest wind, alpine high -1C, and freezing level rising above 1300 m.

FRIDAY: Unsettled with isolated flurries. Moderate west wind, alpine high -3C, and freezing level rising above 1500 m.

We've had few reports from the field over the last few days, however isolated reports suggest 20-30 cm recent snow is sluffing easily where it overlies a crust, but remaining low density with no slab qualities.

Last Wednesday our North Rockies Field team reported a size 2.5 natural cornice failure in the McBride area. This cornice triggered an East facing alpine slope with the suspected weak layer being the deeper weak facets. Just over a week ago, and likely during the first big warm-up, several large size 2.5-3 natural slab avalanches were reported - the suspect failing layer the mid-February facet interface, see some photos of this activity in this MIN. These reports indicate that the buried persistent weak interface remains somewhat active, but likely take a large load to trigger it. That being said the weight of a human and/or machine may be enough to trigger something deeper. It is a low probability - high consequence scenario with large N-E facing alpine slopes being the most suspect.

Snow overnight will start with moderate to strong winds and likely build fresh slabs gaining reactivity as more snow accumulates. Heavier precipitation is forecasted for the North Rockies forecast region, and areas north of Valemount and around McBride could see upwards of 25 cm and an increasingly reactive storm slab.

15-30 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. Large cornices loom over alpine ridgetops. Spring temperatures and sun are producing a melt-freeze snowpack below 1600 m and higher on solar slopes.

A persistent weak layer made up of surface hoar at treeline elevations and a crust with facets in the alpine can be found down 50-150 cm in some parts of the region. Recent reports indicate that some very large avalanches have occurred on this layer in the past week. It seems to need a large trigger like a cornice fall or a rapid flux in weather like a big warm-up. 

• Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
• Dial back your terrain choices if you are seeing more than 25cm of new snow.
• Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
• Remain vigilant for changing conditions.
• Pay attention to cornices and give them a wide berth when traveling on or below ridges.
• Use caution on large alpine slopes, especially around thin areas that may propagate to deeper instabilities.