Avalanche Forecast

A storm system that moved inland to the south late Wednesday cause a period of moderate easterly winds Wednesday, likely redistributing surface snow to unusual aspects, mostly westerly facing near and above treeline. 

Locally new wind slab from the recent easterly winds is possible Friday. This should be mainly on westerly aspects near ridges.

Mostly fair weather with cold temperatures and light winds are expected Friday. The cold temperatures should slow the stabilization of recent wind deposited layers.

Older wind slab from the latest storm cycle should have mostly stabilized, but watch for firmer wind transported snow on all aspects mainly near and above treeline.

The December 8th layer continues to round and gain strength and should be less sensitive to trigger, but remains a concern. Head for lower angle slopes and ratchet back your plans if you experience collapsing or whumpfing or have evidence from snow test results.

Storm slabs from the latest storm cycle should have  stabilized in the Cascades by this time.

Loose dry avalanches remain possible on some steep terrain, protected from recent winds. 

With deep unconsolidated snow in sheltered areas there remains a risk for tree well and snow immersion suffocation. When near trees, ride or ski with a partner and keep them in sight at all times!

Even though the lower part of the below treeline band is filling in, watch for early season travel hazards such as barely covered rocks and open creeks.

Weather and Snowpack

Cold and fair weather early last week allowed for a sun crust to form on many solar aspects and for cold low density snow, near surface faceting and/or surface hoar to become fairly widespread in the Washington Cascades.

These surface snow types were buried late December 8th when the latest storm cycle began. The four day storm cycle, beginning a week ago Thursday, deposited about 1-3 feet of snowfall over most east slope areas ending Monday morning.

Another short period of fair cold weather earlier this week allowed for another round of surface hoar or near surface faceted snow to develop as well as a sun crust on some directly south face terrain.

Locally, strong easterly winds Wednesday, December 14th transported loose surface snow and built new fresh wind slab on less typical westerly facing terrain, mainly near and above treeline and nearer to the crest.

The central and southern portions of the forecast area received up to a few inches of snow overnight Wednesday which may have buried any preserved weak surface snow.

Recent Observations

A regional avalanche cycle was seen December 8th-11th with some avalanches releasing on the December 8th persistent weak layer in the Washington Cascades.

Observations from Washington Pass Saturday indicated about 12 inches of storm snow was still lacking much slab character, but had gained minor slab stiffness in areas. One natural size 1.5 wind slab was noted releasing from below a ridge. No triggered slides were reported but some cracking was noted as the surface snow gained some cohesion.  The December 8th layer of buried surface hoar and/or buried near surface facets was about a foot down as of Saturday.

An observation for the Mission Ridge via the NWAC Observations tab for Sunday in the Lake Marion area indicates a right side up snowpack, but also noted spatial variability and 10-35 cm wind slab giving shooting cracks on loaded slopes.

Pro-observer Jeff Ward was at Washington Pass on Sunday and  noted slightly increasing slab structure near ridges above about 7000 feet with some cracking and limited propagation when testing steep convex slopes.

The pro-patrol at Mission Ridge on Monday gave a very similar report to the Lake Marion report above, that of a generally shallow, but stable snowpack, also noting spatial variation and a sensitive snowpack on local steep wind loaded N-E slopes.

More critically, on Tuesday there was a skier triggered slab avalanche release on the December 8th Persist weak layer in the Highland Bowl back country next to the Steven Pass ski area. The Stevens pro-patrol reports it was on a steep SSW slope at 5400 feet with a 40 cm x 100 foot crown releasing in buried hoar frost and facets on a crust. 

A member of the Stevens Pass pro-patrol reported wind transport on Rock Mountain and especially in the Chiwaukums on Wednesday.

The most recent reports for the Washington Pass is well stated on our recent observations page!