Lawinenlagebericht

Bridgeport Avalanche Center

Bridgeport Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A low-pressure system today brings swirling wind to Sierra ridges and several inches of new snow. Wind-transported snow will create fresh slabs on leeward slopes and human-triggered avalanches are possible. Pay attention to where the wind-blown snow is being transported, heightened caution is recommended in these areas.

Lawinenprobleme

  • Wind Slabs

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

    Mild by Sierra storm standards, the weather system that has begun to impact the forecast area could produce several inches of new snow throughout the day. With a moderate wind shifting to the NE and stronger gusts on ridges, the new snow could produce slab formations of up to a foot or more. Watch the wind and transportation closely, and take notice of which slopes the snow is loading into.  With the right snow speed, snow grains can gently bounce along a ridge and load a leeward terrain feature in its start zone. This 'saltation' effect of the grains occurs during moderately breezy conditions, gently loading up terrain features. 

    (2/6/2023)

    An example of wind blown snow from this week. In this photo the wind is blowing from the East. We had wind blowing from all directions this week, creating slabs on all aspects. 

Avalanche Discussion

Winter weather is back after a sunny week with all types of snow surface conditions out in our forecast area. In one week we transitioned from winter to spring and back to winter again. Solar slopes warmed up as temperatures in the 40's created mild spring-like conditions. Wind from all directions created variable surface conditions across all aspects and redistributed slabs of snow onto the windward side.  Dry loose snow sluffs were observed on wind-sheltered northerly terrain.  The one big question of the week was, what about that PWL? Is it here, is it not here? Several reports indicated that buried surface hoar was present down 40 cm in the snowpack and produced planer results on pit tests. Ski cuts and machine track test cuts did not produce results on this layer. It is possible this layer is out there however its distribution is isolated and would be hard to find.  While PWL's aren't common in the Sierra, we do get our share of cycles where buried surface hoar can remain preserved under the snow and cause problems. Most of the time, this layer gets blasted and broken up by the wind and heavy wet snow. Other times our mild temperatures mixed with settlement cause this buried surface hoar to lock into the snowpack instead of remain like a house of cards. In any event, choose your slopes wisely and dig to confirm the structure of the snowpack in areas you intend to ride. 

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