Hatcher Pass
|
Archives 
|
The Bottom Line
Strong winds from the East have transported snow and created wind slabs 3 to 5 inches thick.
Human-triggered wind slabs are possible at upper elevations on westerly aspects and leeward features. These avalanches will occur on slopes 35º or steeper.
Human-triggered persistent slab avalanches are possible in isolated areas at mid and upper elevations on southerly aspects. These avalanches will occur on slopes 30º and steeper.
Natural avalanches are unlikely.
Winds are forecasted to increase in the afternoon, with extreme winds forecasted for Thursday evening thru Friday. Avalanche danger will increase rapidly during this wind event.
| |
|
 |
 |
 |
|
| 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 have been a few small loose dry avalanches triggered in steep terrain in the last week. No human-triggered or natural slab avalanches have been observed since 12/15.
Loose Dry avalanche near Martin Mine 12/20
| 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 |
Overnight winds from the East with gusts up to 27 mph lasted for 6 hours and have created wind slabs 3-5” thick. Human-triggered wind slabs will be possible at upper elevations on westerly aspects on slopes 35º or steeper. Wind slabs will be found near ridge tops and on leeward features. These avalanches will be small in size. Natural avalanches are unlikely.
Wind effect and texture on Sky Scraper 12/21.
Wind texture and effect on Bullion Mountain 12/21.
These freshly formed wind slabs will be sitting on weak sugary faceted snow that formed during recent cold weather. We expect these wind slabs to gain strength very slowly.
To identify this avalanche problem look for smooth wind drifted snow. Hand pits, pole probes, and other traveling tests will help you identify this avalanche problem. Formal stability tests will also help you identify this problem.
Shooting cracks and collapsing will be red flags for this avalanche problem.
| 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 |
Persistent slab avalanches will be possible in isolated areas on southerly aspects at mid and upper elevations on slopes 30º and steeper. These avalanches will be large in size and fail near the ground. Natural avalanches are unlikely.
In areas where the snowpack is shallower, it will be more likely for humans to trigger a persistent slab avalanche. Use your pole or probe to measure snowpack depth as you’re traveling in the mountains.
The snowpack is slowly gaining strength and it has been a week since any persistent slab avalanches have been observed. This avalanche problem will be difficult to trigger and the consequences will be high.
