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Today’s avalanche problems are Storm Slab, Persistent Slab and Dry Loose. Storm slabs 6-8″ thick and Persistent slabs 1-3 feet deep will be possible to trigger at all elevations and all aspects. Small to large dry loose will be possible to trigger at upper elevation on all aspects.
We received approximately 6” of snow overnight and are excepting 2” today with 16″ of new snow since 2/24.
Join us on Zoom Sunday, February 28th at 7:00pm to meet the HPAC founders and forecasters! You’ll learn about the current state of the snowpack in Hatcher Pass. This is a great opportunity to gain a better understanding of the current conditions, and get to know the folks who help keep us informed about backcountry conditions. Sign up is required, click here to register.
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. |
Hatcher Pass received approximately 10″ of new snow on 2/24 and 2/25. Natural storm slabs, winds slabs, and dry loose were observed within 24hrs after the storm on all aspects and mostly at mid and upper elevation.
One isolated persistent slab was remotely triggered on 2/25. See OBS 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 |
Storm slabs approximately 6-8″ thick will be possible to human trigger today on all aspects at all elevations on slopes 35° and steeper. Natural avalanches are unlikely today. We anticipate seeing many natural storm slabs from last night. Newer dense snow over lower density snow will be easy to identify with pole tests and hand shears. Storm slabs instability will improve within 24-48 hours.
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, 1-3 feet deep will be possible to human trigger today on all aspects at all elevations on slopes 35° and steeper. We have received 16″ of new snow since 2/24. This snow is sitting on a thin, buried layer of rounded near surface facets. Below this layer, there is a near surface facet layer in the mid pack. Near the base of the snowpack there is depth hoar. Overall, the snowpack has poor structure with weak layers teetering between dormancy and activity.
In the last storm cycle on 2/24 we received about 1” of water (SWE). Immediately following this moderate load, we saw some small and large natural activity. Most of the natural slab avalanches failed in the mid pack, and a few failed near the ground in isolated locations.
Yesterday and last night’s storm brought a similar amount of water weight (.8-.9” SWE) with only 6″ of snow, due to the warmth of the storm. We should expect to see some similar activity from overnight in the persistent weak-layers near the surface and in the mid pack, and for the potential for a few isolated deeper slabs releases.
Since we are teetering on the balance point and have some level of uncertainty, we recommend starting your day out assessing the new snow load in safe locations before stepping it up into larger pieces of terrain and steeper slopes. If visibility allows, scan the landscape for fresh avalanches and evidence of this problem. Shooting cracks and whumphing are bulls eye clues for this problem. Instability tests on representative slopes, such as the Extended Column Test, should provide good information for propagation potential and today’s risk.
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 |
It will be possible to trigger small to large dry loose sluffs today in terrain steeper than 35º at upper elevation on all aspects. 16” of new snow has accumulated since 2/24, including 6” overnight. Sluffs at upper elevation have the potential to entrain a lot of snow making an exit challenging or taking you somewhere you don’t want to go. This week’s new and mostly dense snow will be challenging to get to move at mid and lower elevations. The good news is sluffs are predictable and avoidable.