The Bottom Line: This zone received around 2 feet of new snowfall in the last 2 days, and SE winds were howling. Temperatures increased by nearly 20 degrees F.  There was probably a natural avalanche cycle and these fresh storm snow instabilities (3ft deep or more) will be slowly settling down. Avoid all avalanche terrain today, and be especially mindful to avoid terrain traps where even small slides can pile up deep. Stick to the trees, and avoid any steep openings or gullies. Remember that cornices have grown quite large and will be ready to fall. Stay far back and away from all cornices and snow ledges.

Any surface avalanches within the new snow could step down to one or more Deep Persistent weak layers and cause a very wide and deadly avalanche. Consequences are high.

Give runout zones a wide berth. Natural avalanches are still possible and they could be quite large.

Recent heavy snowfall and strong warming is stressing the remaining persistent weak layers deeper down in the snowpack. The result is an increased likelihood of very large and deadly avalanches that can break super wide across a slope.

When seeking out wind protected zones, remember that wind-protected pockets may be harboring buried surface hoar layers. Protected means preserved.

Buried Surface Hoar Layers (These layers have become less reactive in snowpits, but smaller slides could still step down and trigger them):

• Jan 25th melt freeze crust is about 3-4 feet deep (with recent winds and snow, there is a lot of variability on depth of this widespread layer) sitting on top of it are near surface facets, and buried surface hoar from Feb 1-4.
• January 10th surface hoar is now buried about 4-5 feet deep
   

Old Melt Layers and Crusts:

• Dec 31 surface hoar layer is present in the Transitional and Pass zones, about 5 ft deep. This layer caused some natural avalanches in early January.
• A buried persistent weak layer about 8+ feet deep (The “Big Warmup” Layer, Formed Nov 17th) is still a concern. Numerous natural avalanches observed 1/27 likely on this layer.
• A wide safety margin is necessary. This setup could produce avalanches that break wider than expected, and are most likely to be triggered from shallow trigger points like rocks or small trees. You could ride the same slope numerous times until that right spot produces a large destructive slide.

Pit at Old Faithful, 2700’, East aspect on Mar 15 (now has an additional 2ft on top). PST 60/100 End on the Jan 10 buried SH 4-6mm that is rounding down 130 cm

Depth Hoar at the Ground (In thinner areas above 3,000′):

• October snow followed by long cold snaps created depth hoar at the ground in most areas.
• You are most likely to human-trigger this layer from shallow spots around rocks, or trees, or have a surface avalanche step down to the ground on this layer. Any slides that break to the ground are likely to be deadly.

Photos shows 6-9mm advanced depth hoar at the ground down 180cm with ECTP 25 down 80cm on facets below a crust in the Haines Pass Zone at 4,000ft on a NE-aspect.

Snow levels reached up to 1700ft over the last 24 hours. Below that level, there was a lot of rain-on-snow. Wet slabs and large wet-loose avalanches are likely today below 1500ft, especially in open terrain steeper than 32 degrees. This will add to the threat of avalanches today, even down at lower elevations.