Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 25th, 2019–Dec 26th, 2019

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

.

You can trigger recent or freshly forming shallow wind slabs above treeline near ridgelines. Watch for signs of recent or active snow transport, or snow surfaces cracking as you move. While we think that storm slabs associated with a massive loading event late last week have healed, wisdom dictates safe travel practices, particularly on large avalanche slopes.

Discussion

We expect one more day of generally benign weather with winds starting to pick up ahead of a storm approaching from the NW, later in the day. 

Reports indicated 8-15” ski penetration of right-side-up powder on all aspects on Tuesday. This remained preserved on sheltered northerly aspects Wednesday following wind transport which occurred Tuesday night. Sunshine early Tuesday and partial sunshine on Wednesday created thin crusts on southerly aspects. Wind Slabs near ridgelines or steep terrain where a small Loose Dry avalanches could push you into unintended places are the identifiable avalanche concerns at this time. 

The West North zone received 3-4ft+ of snow (7.5in water) from December 18-21. The event produced a widespread avalanche cycle with numerous natural and triggered avalanches to size D3 occurring Friday and Saturday. The storm snow has now settled 11” with a slowing rate of settlement indicative of a stabilizing snowpack. Some Loose Wet avalanche activity occurred earlier in the week as reported to NWAC here. Tuesday and Wednesday, folks have been recreating in Bagley Lakes and on Shuksan arm, testing a variety of steeper terrain features without signs of recent avalanche activity. This has given us some confidence to take storm slabs off the problem list.

On 12/24, Mt. Baker Pro Patrol evaluated several nicely rounding weaker layers near the base of the snowpack on a NE aspect at 5080 ft and found these layers were not reactive in tests. It’s worth keeping these early season weaknesses in the back of your mind given the recent loading event, but we don’t have evidence that they are of concern without a major loading event.

Happy Holidays! We extend our gratitude in advance for submitting observations to NWAC.

Snowpack Discussion

New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.

 

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.