Hatcher Pass
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The Bottom Line
Small Dry Loose avalanches will be possible to human trigger at mid and upper elevations in specific terrain, 40° and steeper.
Getting caught in a fast moving small sluff in steep terrain will have large consequences if you then encounter rocks or other hazards.
The snowpack is shallow, coverage is thin, and rocks and other hazards are close to the surface.
Winds are expected to increase on Sunday which will quickly build sensitive wind slabs and increase the avalanche danger. Saturday will be the choice day for riding this weekend, as avalanche conditions remain relatively safe ahead of the storm. Monday may bring up to 1 foot of new snow.
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| Travel Advice | Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. | Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. | Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. | Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. | Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain. |
| Likelihood of Avalanches | Natural and human-triggered avalanches unlikely. | Natural avalanches unlikely; human-triggered avalanches possible. | Natural avalanches possible; human-triggered avalanches likely. | Natural avalanches likely; human-triggered avalanches very likely. | Natural and human-triggered avalanches certain. |
| Avalanche Size and Distribution | Small avalanches in isolated areas or extreme terrain. | Small avalanches in specific areas; or large avalanches in isolated areas. | Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. | Large avalanches in many areas; or very large avalanches in specific areas. | Very large avalanches in many areas. |
This week numerous loose dry avalanches were human triggered. Two small wind slabs were human triggered in the forecast area at upper elevation ridgelines on leeward aspects after a moderate wind event on November 29-30. A few more small wind slabs were human triggered just outside the forecast area near Lone Tree Gulch, and a single natural, small wind slab was observed near Mt. Sovereign. It seems this area saw a little more wind than our forecast area.
Some very small loose dry avalanches naturally failed just after 2″ of new snow accumulated on the evening of November 30th to December 1, and again just after 1″ of new snow accumulated the evening of December 1-2. These were all small in size.
Dec 2 or 3, Natural point release, loose dry avalanche on Marmot, Lodge Run, West, 3800′
| Signal Word | Size (D scale) | Simple Descriptor |
| Small | 1 | Unlikely to bury a person |
| Large | 2 | Can bury a person |
| Very Large | 3 | Can destroy a house |
| Historic | 4 & 5 | Can destroy part or all of a village |
It will be possible to human trigger small loose dry avalanches (sluffs) in specific terrain, 40° and steeper at mid to upper elevations and on all aspects. Natural loose dry avalanches are unlikely.
Due to the extent and depth of the weak sugary snowpack, loose dry avalanches may surprise you as they will be capable of dredging deeper into older snow gaining both volume and speed.
Getting caught in any small avalanche has serious consequences at this point in the season. In many cases loose dry avalanches are failing at the ground level, exposing rock hazards.
Secondary to the loose dry avalanche problem are isolated locations of old thin wind slabs at upper elevation ridge lines on leeward aspects, SW to NW.. This is a very patchy small problem which is lingering. These slabs formed on Nov. 29-30 during a moderate wind event and sit on weak, faceted snow. Shooting cracks, whumphing and drummy sounding stiff snow surfaces are bulls eye clues for this problem.
Ski cutting is an acceptable tool for these slabs as long as they are thin and small in size. In the rare case that you trigger one of these in steep terrain (40°+), you can be assured that it will entrain weak sugary snow along its descent and significantly increase in size and danger.
Triggering any avalanche above terrain traps will increase the hazard.
Occurred December 2 to 3?
Terrain selection. Hatcher Pass is heavily tracked, and all the low hanging fruit has been consumed. This adds pressure to our decision making when our goals are fresh powder, pushing backcountry users into more and more terrain that contain dangerous terrain traps.
Keep this at the forefront of your mind and decision making as you get into the backcountry today, and stack the odds in your favor.
As a wise mentor once told me, “Only break one rule at a time.” The generally good stability of the snowpack has justified some of these terrain choices, but having a large margin for error is never a bad thing. Also, there are still terrain choices out there with great snow lacking terrain traps. It might take a little longer to get there in the cold, but its worth it.
NWS is forecasting an incoming storm which should arrive in the early hours of Sunday morning. A few inches of snow is expected, however the big news is the wind. Winds are forecasted and models are showing strong wind speeds capable of transporting and drifting snow. There is a lot of low density snow available for transport and this means any sustained strong winds will quickly build sensitive wind slabs and the avalanche hazard will rise quickly. Keep your fingers crossed for low wind speeds and new snow.
Motorized Access As of December 2, all areas remain closed to snow machine use due to insufficient snow.
