Hatcher Pass
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The Bottom Line
Strong to extreme winds have built and will continue to build LARGE WIND SLABS above 3000′ throughout the day.
Wind slabs 12 to 18 inches thick, and growing in size throughout the day, will be likely to human trigger on southwest to west aspects and cross loaded features at upper elevation on slopes steeper than 35º.
Persistent slabs, 2 to 4 feet thick will be likely to human trigger on south to west aspects at mid and upper elevation on slopes steeper than 30º.
Natural avalanches are possible.
Avalanche hazard, blizzard conditions, treacherous driving, and very cold temperatures are good reasons to not go into the mountains today.
Blizzard Warning in effect from December 22, 08:00 PM AKST until December 23, 08:00 PM AKST
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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. |
| 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 |
Wind slabs 12 to 18 inches thick, and growing in size throughout the day, will be likely to human trigger on southwest to west aspects and cross loaded features at upper elevation on slopes steeper than 35º.
We expect winds to increase throughout the day, transport more low density snow onto leeward aspects, and build larger wind slabs. It will be possible by end of day for wind slabs to step down and fail at the ground in the basal facets on southerly aspects.
Winds are increasing on Marmot 4500′
Wind texture on Thursday on Skyscraper ridge. 4000′
A visual clue of strong winds and drifting snow is flagging or pluming at ridgelines.
Wind slabs are typically easy to identify but not today because of blizzard conditions. 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 more likely throughout the day to human trigger on south to west aspects at mid and upper elevation on slopes steeper than 30º.
Natural avalanches will be possible.
As winds increase and drift snow, this avalanche problem will become larger and more reactive.
The persistent slab that we have been talking about all season consists of the entire snowpack and has the potential to fail in the basal facets at or near the ground.
Shallow locations in the snowpack will be more likely locations to trigger the persistent slab.
Avalanche behavior may be difficult to predict.
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.
