Bulletin d’avalanche

Banner Summit

Sawtooth Avalanche Center
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Danger d’avalanche

Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 5 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Watch for and avoid fresh wind drifts and slabs. You will find more, and larger, drifts and slabs as you climb from middle to upper elevations. Where rain is falling, steer clear of steep slopes if you are sinking into a wet, mushy snowpack.

We will issue our last daily Avalanche Forecast of the season this Sunday, April 5th. We will issue General Avalanche Information updates through late April or early May.  

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    You could find wind slabs up to 2 feet thick in exposed terrain. Wind slabs are largest and most widespread at upper elevations.

    Recent cornice growth, pillows, and dunes are all clues that wind was at work moving snow. Look for shooting cracks as evidence of fresh wind slabs and a nudge to move to softer snow on more sheltered slopes. These slabs commonly form beneath ridgelines, on the sides of cross-loaded gullies, and lower in cirques below large cliff bands, chutes, and couloirs.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    The rain-snow line is expected to linger around or above 7500' today, and that keeps wet avalanches in the mix. These are most likely on very steep slopes where you find a wet, unsupportable snowpack.

    Climb to higher elevations to avoid tangling with these slow-moving but surprisingly powerful and difficult-to-escape avalanches. Don't spend more time than needed below large avalanche paths where steady rain is falling; rain-driven wet avalanches can release naturally. 

    Large Wet Loose avalanche in the northern Sawtooths near Williams Peak. NE 9000'.

    Photo: Sawtooth Avalanche Center

Avalanche Discussion

Just when we thought winter had punched its timecard and clocked out - April Fools - it's back! With the return of snowfall, it's worth turning our brains back into winter mode and out of the simplified spring-diurnal mindset. Keep your head on a swivel for changing conditions if you're out enjoying the cold new snow, especially in areas where you find more than 6" of fresh snow. Spring storms are notoriously spotty in character, with large amounts of variability in the timing and quantity of snowfall across the landscape. Additionally, convective storms could produce graupel or other snow crystal types that form sensitive mid-storm interfaces. These interfaces make great failure layers for even thin wind slabs that quickly form above them.

Conveniently, the recent warm weather has solidified much of the snowpack below this new snowfall. On steep slopes where new snow is accumulating on firm, hard ice or wind-hammered surfaces, loose snow avalanches (sluffs) could release naturally or be easy to trigger and run faster and further than expected. Given the variety of conditions you may experience in the mountains today, be ready to pull the plug and switch to a more conservative plan B if you see obvious signs of instability or feel the hairs on the back of your neck stand up.

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