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Early spring conditions have dominated HP for the past few days but we still have lots of winter left! It’s been over a week since avalanche cycles produced numerous large and very large avalanches covering and burying the road in an est. 15 to 25 feet of debris.
Although it is becoming harder to trigger a large avalanche, the possibility still exists. It will be possible to human trigger a deep persistent slab 3 to 4 feet deep on all aspects at mid and upper elevation on slopes steeper than 30º.
It will be possible to human trigger a persistent slab 2 to 3 feet deep on all aspects at low elevation on slopes steeper than 30º.
It will be possible to human trigger small wind slabs up to 6 inches thick on west to north aspects at upper elevation on slopes steeper than 35°.
Natural avalanches will be unlikely today.
The HP road remains closed at mile 11. DOT plowed up to Mile 11 on Friday.
AK State Parks issued an executive order on 2/24 to close the Hatcher Pass East Management Area. Page 1, Page 2 and public comment here.
HPAC will continue to provide avalanche information to the best of our abilities using our weather resources and weather stations and limited backcountry access.
We recognize the enormous amount of work required to clear the road and look forward to working with all agencies to get our community back out recreating.
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. |
No recent avalanches have been observed or reported since the Valentines Cycle 2/14-18 and the Presidents Storm 2/21-22.
For avalanche photos related to these cycles see obs here and forecasts here.
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 |
Deep Persistent Slabs up to 4 feet deep will be possible to human trigger on all aspects at mid and upper elevation on slopes steeper than 30°. Avalanches that were touchy last week will be stubborn to trigger this weekend.
Slabs are thicker and weak layers from Dec 26 and Nov are buried deeper at mid and upper elevation where more snow accumulated last week and temps remain colder than low elevation.
Remotely triggering an avalanche above you or on an adjacent slope is still possible. Deep slabs are inherently more stubborn to trigger because of the depth of the weak layer but carry significantly more consequence. Thin spots in the snowpack will be more likely locations to trigger an avalanche.
To identify this avalanche problem use poles/probes to identify the Dec 26th rain crust and weak sugary snow below. Formal stability tests will be challenging and unreliable due to weak layers being buried so deep.
Human triggered and remotely triggered avalanches will be possible days or weeks after a storm.
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 3 feet thick will be possible to human trigger on all aspects at low elevation, on slopes steeper than 30º. Natural avalanches are unlikely today.
Below 2500′ received less snow during the past two storms. In addition, over the past 48+ hours temps have been 33 to 40ºF and the snowpack has settled 8″ since 2/22.
Frostbite station is reporting slightly cooler temps this morning at 29º at 5am.
To identify this avalanche problem use poles/probes to identify the Dec 26th rain crust and weak sugary snow below. Formal stability tests may be challenging and unreliable due to weak layers being buried so deep.
Human triggered and remotely triggered avalanches will be possible days or weeks after a storm.
When the avalanche problems are complex and we have limited snowpack data, it’s time to focus on safe travel protocol. In avalanche terrain, only expose one person to steep slopes at a time, choose safe zones out of the reach of avalanches for grouping up, always have a spotter in a safe location, everyone carries a beacon, shovel, and probe, and are prepared and practiced for companion rescue.
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 |
Small wind slabs up to 6″ thick will be possible to human trigger on west to north aspects at upper elevation on slopes above 35º. Natural avalanches are unlikely.
The Marmot weather station anemometer came back online Friday afternoon. There is some uncertainty as to how long winds blew and the intensity since the station has been rimed for 10 days. A significant amount of terrain appeared wind affected during our flights over the past week.
To identify this avalanche problem, look for smooth wind-drifted snow and rounded lensed shape features. Use hand pits and pole/probe tests to identify stiff hard snow sitting on top of soft low density snow. Whumping and shooting cracks are red flags for this avalanche problem.