Hatcher Pass
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The Bottom Line
Persistent slabs will be possible to human trigger today. Small thin wind slabs will be possible to human trigger with an increase in wind this afternoon.
Small to large, human triggered persistent slabs are possible at all elevations on SW-N aspects on slopes greater than 30°; natural avalanches are unlikely. These avalanches will be found in specific terrain where stiff hard dense snow is sitting over weak sugary facets.
Even a small avalanche can have high consequences if you’re traveling above a terrain trap.
Special AnnouncementsHatcher Pass Avalanche Center is currently looking for additional board members who are motivated and passionate about sustaining a local grassroots avalanche center. If interested send an email to andydennis@hpavalanche.org
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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. |
There was one human triggered avalanche reported this week click here for more info. There were several natural avalanches that released during the wind event earlier in the week.
| 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 |
Strong winds with gusts up to 52mph on 12/5-6 formed stiff hard slabs 12-18” thick, which are now sitting on top of weak sugary snow. This faceted snow was formed due to cold clear weather last month. Human triggered persistent slabs are possible at all elevations on SW-NE aspects; natural avalanches are unlikely. These avalanches will be small to large in size. Persistent slab avalanches will be possible on slopes 30° degrees or steeper.
To identify this avalanche problem look for stiff, one finger to pencil hard snow, sitting on top of low density sugary facets. Texture of the snow can also help you identify if this slab is present. Wind drifted snow, smooth lens shaped features and scalloped snow are indicators that a hard slab is present. Instability tests, pole/probes and hand pits will all be tools to identify this persistent slab problem. Whumping and shooting cracks will be red flags for this avalanche problem.
The recently formed slab is hard, which means that it will be capable of breaking above you and not just at your feet. If a slab breaks above you, it will be harder to escape and increase the likelihood of being caught. Use conservative travel techniques when traveling in avalanche terrain. This means spreading out when ascending slopes, riding slopes one at a time, and stopping in safe areas that are out of harm’s way.
Wind effected snow on Marmot
Stiff dense slab sitting on top of weak faceted snow.
This pit had poor structure, moderate strength, and propagation potential. Hard slabs sitting on top of weak faceted snow.
| 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 |
Winds may increase today, but there is some uncertainty in the forecast. As of this morning we are seeing Easterly winds increasing for the latter half of the day and then diminishing tomorrow. The little snow that’s available for transport will create small thin wind slabs at mid and upper elevations on western aspects. Small human triggered avalanches will be possible, natural avalanches are unlikely. These wind slabs will form on surfaces that are already firm and will not bond well.
If we see strong winds today expect the wind slab hazard to steadily increase through the day and overnight.
Wind slab development requires both wind and available snow for transport. December 5-6’s wind event stripped much of the available snow. Today’s short-term spike in wind speed combined with a small amount of available snow for transport (AST) will likely result in small wind slabs on leeward aspects.
East winds will build wind slabs on leeward, Westerly aspects. Pay close attention to wind speed and direction. Leeward aspects will be 180 degrees to the prevailing winds. Small shifts in wind direction can change the distribution of this problem.
