Lawinenlagebericht

Southeast Mountains

Crested Butte Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Snowfall overnight and today will bring 5 to 12 inches to the Southeast Mountains and could create dangerous avalanche conditions, particularly on drifted terrain features.  The most concerning terrain faces west to north to east where buried weak layers exist around 2 - 3 feet below the surface; avalanches could break into old snow creating large avalanches.  On sunny slopes, the new snow is falling on thick crusts and avalanche concerns are anticipated to remain in the storm snow.  Collapsing and cracking are clear indications that buried weak layers are primed to avalanche.  Use caution around all steep terrain particularly drifted terrain, and choose lower-angled slopes where you find 8 inches or more of new snow.

Lawinenprobleme

  • Persistent Slabs

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

    You can trigger slabs 2 to 3 feet thick that fail on a layer of faceted snow buried below the storm interface (the February "sand box" weak layer).  This problem is can be found on west through north through east slopes.  The new snow will likely awaken this weak layer and create dangerous avalanche conditions.  Slopes that avalanched a week ago remain highly suspect (see this observation for 'repeat offender' potential).  Persistent Slab avalanches can be triggered remotely from below or adjacent slopes.  Collapsing and cracking are clear signs that this weak layer has been overloaded and primed to avalanche.  Use caution on slopes facing the north half of the compass.  

    This photo from Cement Creek illustrates how persistent slabs can be triggered from a long ways away from the start zone.  The avalanche was remotely triggered by a snowmobile on 2/27.

  • Wind Slabs

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

    With less snow in the southeast mountains, storm snow instabilities are more likely to be found in drifted terrain features at upper elevations.  Look for active transport and scoured areas adjacent to leeward features to clue you into fresh wind-drifted slabs near and above treeline.  You can anticipate finding them below fresh cornices, below ridgetops, and cross-loaded into gullies. 

    An example of a wind-drifted slab immediately below a ridge top.

Avalanche Discussion

A storm system is increasing the avalanche hazard and creating dangerous conditions.  Storm totals in the Northwest Mountains range from 6 to 12 inches as of 6 am and 3 to 7 inches in the Southeast Mountains.  Mother nature will add to these totals with another 3 to 6 inches during the day.  The snowfall is favoring areas in the Northwest Mountains and you should expect to find the most dangerous conditions there.  Areas in the Southeast Mountains that border the Northwest Mountains may become dangerous as well.

The new snow is creating the greatest concern on slopes facing the north half of the compass.  On shady slopes, the concern is for avalanches to break 2 to 4 feet deep on the "February drought" layer.  The "drought" facet layer was initially buried over a week ago and produced a widespread avalanche cycle during last weeks storm and resulted in many human-triggered avalanches.  Unfortunately, this layer was thick enough that it was not destroyed or removed by natural avalanche activity and remains a worrisome problem even on slopes that avalanche during the last storm.  If you are venturing into terrain with any northerly component dial back your slope angles and anticipate human-triggered avalanches to be likely with natural avalanches possible during periods of heavy snowfall.  Avalanches breaking on the February facet layer will be big enough to bury you in many locations.

On southerly-facing terrain, the new snow is falling on melt/freeze crusts and avalanches are expected to remain in the storm snow.  Expect drifted, sunny terrain features to be more dangerous as southwest to west winds transport the new snow into thicker slabs on leeward terrain.  Take the time to inspect the bonding between the storm snow and the old crust before you commit to avalanche terrain on sunny slopes.

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