Avalanche Forecast

A front is expected to move through the region overnight Sunday, followed by showers Monday. Light to moderate snow at cool temperatures and moderate winds should build some fresh wind slabs above treeline by Monday. 

Cooler temperatures and light showers Monday should allow for storm layers to begin settling.

Watch for recent wind slabs in higher terrain on steep lee slopes, mainly NW-SE facing.

Recent cornices are very large and have likely been weakened during this most recent storm cycle. Natural cornice releases and resulting slab avalanches are dangerous and unpredictable. Give cornices a wide berth if traveling along ridge-lines and avoid slopes below large cornices. See a blog post regarding cornices here.

Other avalanche problems not listed that may be encountered on Sunday include:

Storm slab in more sheltered areas above treeline that experienced rapidly accumulating snowfall for more than a few hours. This is most likely in the Mt Baker area!

Remember that solar effects can rapidly increase the touchiness of various types of avalanches at this time of year, loose-wet, cornices, glide and wind slab to name a few.

Weather and Snowpack

Heavy rain in mid March has left behind a well consolidated old snowpack with one or more strong melt freeze crusts in the upper snowpack.

A series of strong spring storms began about midnight Wednesday of this past week. From midnight Wednesday through Sunday morning, the Mt Baker area has received over 5 inches of water equivalent. Most or all of this fell as snow near and above treeline.

Very strong winds Friday and Friday night built large wind slabs and fresh cornices during sustained SE-SW winds averaging over 35 mph with gusts over 80 mph! These winds were so strong that wind slabs were less widespread and formed lower on leeward slopes than typical.  

Cooling, diminishing showers and winds Saturday allowed for the storm snow to begin settling and stabilizing.

Fair weather and sunshine or filtered sun Sunday allowed for more consolidation and some surface snow melt on all but steep shaded slopes in higher terrain.  

Recent Observations

North

NWAC pro-observer Lee Lazzara was at Little Devil Peak in North Cascades on Monday 4/3. Near and above treeline Lee found about 4 inches of recent storm snow over the most recent crust, and wind slabs averaging about 1 foot on N-E aspects below ridges. Snowpack tests indicated triggering of wind slabs to be stubborn. There was evidence of recent large cornice failures. The recent strong rain crust dominated the snowpack below treeline with shallow wet snow conditions during the afternoon. Shallow cold snow was preserved on steep shaded terrain near and above treeline.

The Mt Baker pro-patrol reported easily ski triggered, loose wet avalanches Thursday morning, peeling off the most recent 4-6" inches above 4500 ft and running well. Below 4000 feet, the random snow pillow collapse would trigger natural loose wet avalanches due to above freezing temperatures and continuing rain. 

Saturday morning, the Mt Baker patrol reported recent wind slabs were more isolated in the terrain and had formed lower down below ridges due to the strong transporting winds Friday.

NWAC's Lee Lazzara travelled to the Hidden Lakes Peak area in the North Cascades Sunday, 4/9. Recent storm snow ranged from about 1 foot near treeline to about 2 feet above treeline. Recent wind slabs were noted as well as some fresh wind transported snow on many cross loaded features. Storm snow remained cold and dry on steeper shaded terrain at higher elevations. Wind slabs appear to require a bit more settling time before venturing into steeper committed terrain.  Solar affects were beginning to make shallow, loose wet slides possible by late morning on all but shaded slopes above treeline.  

Central

The Alpental pro-patrol in a pit on the upper mountain reported alternating layers of stable crusts and wet snow in the upper snow pack on Friday. Below about 3500 feet, the snowpack was characterized by deep layers of large grains of wet snow.

A report via the NWAC Observations page for Friday indicated easily triggered, loose wet avalanches on Tonga Ridge west of Stevens Pass on Friday.

NWAC's Jermey Allyn was in the Alpental Valley, Sunday 4/9. Recent storm snow of about 6-8 inches was hanging in there on shaded terrain, over a very strong crust. On all but the steep shaded terrain at high elevations, shallow surface snow became wet and cohesive by midday as solar affects took hold. There was no evidence of wind slabs in this terrain, but no observations were made in true above treeline zones. Less storm snow and lighter winds have been the rule in the passes, however, so wind slabs are less likely in these zones. 

South

No recent observations.