Hatcher Pass
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The Bottom Line
WIND SLABS up to 2 feet thick will be LIKELY to human trigger on SOUTHEAST to WEST aspects at all elevations, on slopes steeper than 35º. Head’s Up! It will be possible to trigger a wind slab on steep slopes at low elevation like the road run. Natural avalanches are possible.
PERSISTENT SLABS 2 to 4 feet thick will be LIKELY to human trigger in specific locations on all aspects on slopes steeper than 30º. Natural avalanches are unlikely.
Remotely triggering an avalanche should be on your radar today.
Many large avalanches were observed on Friday including one on Marmot that came close to hitting the road.
The Matanuska wind has radically changed conditions over the past 24 hours.
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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. |
Numerous natural wind slab and persistent slab avalanches were observed on all aspects, but primarily on SE to W, at all elevations on Friday as a result of strong to extreme wind gusts for 20 hours.
12.23 Archangel 2, Natural SE 4000′
12.23 Debris lower Marmot 1 gully near road
12.23 Road cut near Gateway to Hatcher Pass, Natural SE 1200′
12.23 Sunnyside of Hatch, Natural SE 4400′
12.23 Above archangel trail, Naturals SE 4200′
12.23 Marmot Death Gully, Natural SW 4000′- photo Dan Amyot
| 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 gusting E/ENE 30-71 mph for almost 20 hours yesterday have radically transformed the mountain landscape at Hatcher Pass.
As of 3am this morning, winds have finally died down.
Wind slabs up to 2 feet thick will be likely to human trigger on southeast to west aspects at all elevations, on slopes steeper than 35º.
Natural avalanches are possible.
Expect wind slabs to have bonded poorly with near surface facets and or surface crusts that were exposed during the wind event.
Wind slabs may step down into the persistent slab, increasing the size and consequence of any avalanche.
12.23 Marmot 1, Natural SE 3800′. Multiple avalanches can be seen here that all funneled into gully #1 and came close to the road. This avalanche occurred around 12:30pm .
12.23 Marmot 1 Natural. Same avalanche as previous picture.
A visual clue of strong winds and drifting snow is flagging or pluming at ridgelines.
Wind slabs are easy to identify. Look for hard snow sitting over weaker snow, smooth and rounded or lens shaped features. Shooting cracks or whumping are signs of instability and indicators of this avalanche problem.
Expect the wind slab problem to improve within 24-48 hours after winds subside.
| 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 slabs, 2 to 4 feet thick will be likely to human trigger at all elevations on slopes steeper than 30º. Natural avalanches are unlikely.
This problem will be found primarily where yesterdays wind built new slabs, overloading the weak basal facets near the ground, on southeast to west aspects.
Shallower locations in the snowpack , on any aspect, will be possible locations to trigger the persistent slab.
The persistent slab consists of the entire snowpack and has the potential to fail in the basal facets at or near the ground.
12/23 Stairstep Bowl near Banana Chutes, Natural, E 3900′
In addition to larger terrain, it will be possible to trigger an avalanche in smaller terrain we usually do not focus on such as the road run, fishhook creek gully side walls or the slope above the sledding hill. Much of this terrain funnels into terrain traps which will compound the risk of an avalanche.
12.23 Marmot Death Gully, SW 4000′
12.23 Government, Natural NE 4400′. Peak 4600′ Lowers, Natural NE 3600′
Avalanche behavior may be difficult to predict especially as slabs get thicker and weak layers get buried deeper on leeward aspects.
We observed numerous large persistent slab avalanches on Friday.
Pole/probe tests and formal stability tests will help you identify this problem. Whumping and shooting cracks will be red flags for this avalanche problem but may not be present prior to triggering an avalanche.
If you head into avalanche terrain today, utilize strict safety travel protocols, travel one at a time from safe zone to safe zone, only have one person on slope at a time, ensure all members of your party are carrying and know how to use beacons, shovels and probes, and avoid slopes with terrain traps.
