Lawinenlagebericht

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Haines Avalanche Center
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Lawinengefahr

Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The avalanche danger is MODERATE above 2,500' and LOW at elevations below. An ongoing inversion has caused above-freezing temperatures combined with solar radiation to increase the likelihood of wet avalanches on south faces up to 6,500ft. Weak snow interfaces exist in the snowpack and remain possible for human triggering on slopes greater than 30 degrees.  Stable weather can build confidence quickly, now is the time to pay close attention from one decision point to the next.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2.5

    Sunny and warm weather in coastal regions can make us lose sense of it all, but right now it's important to pay attention. Slopes that may be inviting could have buried persistent weak layers and a poor snowpack structure. Signs of instability could be clear such as large whumphs and collapses, or non-existent. Known weak layers include buried facets, surface hoar, and melt-freeze layers. 

    Remain suspect of unsupported slopes and shallow areas in the snowpack, where you could most easily initiate a slide. Even smaller avalanches could be dangerous enough to have high consequences. Weak layers may be more or less apparent in certain areas which makes it tricky when mapping the problem. Utilize cautious route-finding and minimize exposure by traveling one at a time. 

    Beware of cornices and wind lips that could be sensitive due to the warm temperatures and solar radiation. Last weekend's storm had strong south winds that produced recent cornices on W-NW aspects. We should give these a wide distance for safety and minimize our time spent near them.  Cornice failure can be a large natural trigger for an avalanche.

    (2/14/2024)

    January 10-11th storm cycle had strong south winds that formed cornices along ridgelines. Cornice failure can trigger persistent layers in steep terrain below.

    Photo: Haines Avalanche Center

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Warm temperatures in the alpine and strong sun could cause wet loose avalanches on solar aspects. The third day of an inversion will bring above-freezing levels up to 6,500ft. It is also possible that upper elevations did not see a hard overnight freeze that would increase the possibility. Sunshine and warming temperatures cause surface snow to lose cohesion.

    Wet-moving snow can entrain heavier snow that is more difficult to escape from. They can also break into deeper snow layers to cause persistent slabs (see Problem 1). Pay close attention to signs that the snowpack is warming which include point releases, pinwheels, and roller balls. Keep tabs on outside air temperature in sunny terrain with slopes greater than 30 degrees.

    Point releases, or roller balls that fan out down the slope are indicators of wet loose avalanche activity. Often this occurs area shallow areas or cliff bands.

    Photo: Sawtooth Avalanche Center

Avalanche Discussion

The people you go out with, how you communicate, and how you practice risk reduction as a team throughout the day are equally important as the conditions. Always practice safe travel techniques and terrain management- only exposing one person to a slope at a time, avoid grouping up in run-out zones, and re-consider islands of safety to truly limit your group's exposure. Carry radios, first-aid, and a two-way emergency communication device. Take an avalanche course, and practice companion rescue often with your riding group. Every scenario is different, so it pays to be prepared.

 

Recent weather history and snowpack layering:

  •  Feb. 13-16th - An inversion brought freezing levels as high as 7,000ft. Sunlight and melt-freeze are weakening the new snow surface via recrystallization and surface hoar growth at-and-below the treeline.
  • Feb. 10-11th - Low pressure returned with strong southeast winds, increasing temperatures, and 1-1.5" of snow water equivalent (SWE). This storm produced a natural avalanche cycle on persistent weak layers.
  • Feb 7-8th - Cold temperatures and calm winds produced surface hoar and near surface faceting.
  • Feb 2-3rd - Light snow over our regions with the highest accumulations near town with 3-5".
  • Jan 31st-Feb 3rd - An intense northerly outflow event brought W-NW-N wind through the region. This was accompanied by another sharp drop in temperature with a maximum low of -15F at the Haines Pass. Another flip-flop weather event saw temperature increase between 25-40 degrees Fahrenheit.
  • January 27-29th - A two-pulse pineapple express event with ~6" total SWE. During the first wave, Jan 26-28th, 2-3" of SWE fell as temps climbed, with freezing levels peaking up to 5,000'. This was when a D3.5 slid over the Haines highway at 21 miles.  In part two of the event on Monday, Jan 29th, there was another 2-3"+ of SWE, but in 24 hours, it was colder with 2,500-3,000' freezing levels and moderate to gusting strong S-SE winds. Both these events helped create the current widespread melt-freeze surface crust nicknamed the late January Pineapple Express crust. 
  • January 2024 - Cold temperatures most of January faceted and accelerated the weakening of persistent snow grains throughout the snowpack: at the surface, below wind slabs, near melt-freeze crusts, and on the ground, especially in areas with a shallow snowpack. Three major temperature dips occurred around Jan 11th, Jan 19th, and Jan 22nd.
  • December 29th - The end of the year (EOY) melt-freeze crust is from when above-freezing temperatures  ~3,000ft- 4,000ft or higher caused the formation of a thick ( 1" +/-), widespread melt-freeze crust down 20-50cm. The cold weather in mid-January faceted and weakened snow around the crust. The "late-January pineapple express" had avalanches that released EOY instabilities in some areas but inconclusive in others.

 

 

Help us gather information about weather, snowpack, and avalanche activity by reading and submitting field observations. Useful observations can be anonymous and include: 

  • Avalanche Activity: Natural or human-triggered
  • Signs of Instability: Cracking, collapsing, or whumping
  • Red Flag Weather: Precipitation, wind loading, warming temperatures and rain-on-snow
  • Persistent Weak Layers: Surface hoar growth, snow depth, persistent weak layers, etc
  • Snow Pits: Stability test results, layers of concern, total snow depth, location, elevation, aspect, etc 

 

Were you caught, carried, injured, or buried in a slide? We are all human and can benefit from anonymous lessons learned. Please report incidents to Haines Avalanche Center staff confidentially.

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