Avalanche Forecast

A period of light to moderate rain and snow at rising freezing levels is expected Wednesday night along with strong S-SW  ridgetop winds. Showers should taper quickly Thursday morning. A modest cooling trend is expected by early Thursday, however, the new storm related danger will continue through Thursday due to strong southwest winds loading lee slopes during showers Wednesday night. 

Storm slab instabilities should be stabilizing, but may still be sensitive Thursday. Wind slabs will continue to build Wednesday night and early Thursday on lee slopes, generally facing NW-NE.  Earlier formed wind slabs may still be reactive Thursday and may add to the increasingly complex snow structure, by Thursday.

Conservative terrain selection will be essential near and above treeline to avoid wind loaded terrain and features. Choose moderately angled terrain and avoid wind loaded slopes, saving those steeper lines for another day.

Non-avalanche hazard: Despite our seasonally, healthy snowpack, many creeks are open and difficult to cross due to the periodic warm temperatures and rain events.  

Weather and Snowpack

Very mild weather a week ago allowed for the formation of melt-freeze crusts, especially on solar slopes in most areas by Friday. Also during this period, wide-spread surface hoar formed in the NE Cascades, mainly surviving outside of steeper solar aspects. 

A weak front brought light amounts of rain and snow Friday night to Saturday morning, burying the surface hoar layer in the Washington Pass area on 2/26. 

A Pacific frontal system passed the Cascades midday Sunday. A few inches of snow accumulated through the early afternoon above 3-4000 feet near the Cascade crest with rapid drying and very little accumulation further east. Alpine winds were strong with significant W-SW transport winds. By Monday morning, 2-10 inches of new snow had accumulated along the east slopes accompanied by a cooling trend. 

Another strong frontal system brought 8-20 inches of snow along the east slopes Tuesday through early Wednesday along with a slow warming trend. Rain may have pushed as high as 4500-5000 feet along the central and northeast Cascades Tuesday afternoon before cooling Wednesday morning.  

We are no longer tracking any layers of concern formed earlier this winter in the mid or lower snowpack, due to lack of recent activity and confirming field observations. 

Recent Observations

NWAC pro-observer Jeff Ward was out near Washington Pass on Thursday and found powder and good ski conditions on north to east slopes. Surface hoar up to 15 mm was also seen on non-solar slopes.

Jeff was out again on Friday and noted widespread 6-8 mm surface hoar on non-solar slopes. On Saturday, Jeff noted the surface hoar buried intact in the Washington Pass area, specifically the Cedar Creek drainage.

NWAC observer Tom Curtis was out at Jove Peak Monday. Jove Peak is NE of Stevens Pass and often overlaps snowpack characteristics of both the east and west slopes of the Cascades. Tom noted few instabilities in the upper snowpack until he observed a large natural wind slab avalanche (R2/D2) on the north side of Jove Peak that probably released Sunday night. The winds slab was 40 cm in depth and stepped down to a 2 mm buried surface hoar layer at 50 cm. The buried surface hoar was rounding, but clearly still sensitive to new loading.