Bulletin d’avalanche

Mount Shasta

Mount Shasta Avalanche Center
Voir sur la carte

Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
Open full map
Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Today is a good day for the deep, no doubt, but NOT the steep. Avoid steep terrain due to multiple avalanche hazards. Over a foot of new snow and moderate SW wind is expected in the next 24 hours. Temperatures will remain cold. Additional hazards include poor visibility, deep snow travel, and hazardous tree wells. 

Remember, if the snowpack is in question, terrain is the answer. If you're not in avalanche terrain, you can't get buried by an avalanche. Slopes 30–45 degrees is avalanche terrain. Being able to identify and avoid avalanche terrain is one of the most crucial skills for backcountry travelers. 

Problèmes avalancheux

  • Storm Slabs

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

    Over a foot of new snow is expected in the next 24 hours. Be especially cautious on slopes with strong slab characteristics. This hazard typically lasts a few hours and may peak later today or overnight during the storm’s climax. Watch for shooting cracks on small test slopes as a key warning sign. A storm slab occurs when a cohesive layer of new snow breaks within the storm snow or at the interface between new and old snow.

    Yesterday, slab characteristics were poor below treeline, but today could be different. It's up to you to evaluate in the field. Slopes steeper than 35 degrees will be most suspect.

    Example of a storm slab in near treeline terrain

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–3

    Recent observations near and above treeline have been challenging, but wind slabs could be several feet deep, resting on a firm bed surface. Large cornices formed during recent storms may remain weak and unstable as well. Winds have predominantly blown from the west/southwest, averaging 13 mph with gusts up to 42 mph over the past three days. Wind slab hazards are confined to windy areas near and above treeline, forming in predictable locations such as leeward ridges, bowls, and cross-loaded gullies. These slabs vary in hardness and thickness, often appearing smooth, rounded, and sometimes sounding hollow. Watch for blowing snow and cracking in drifted areas—key warning signs of instability. To avoid this hazard, stick to sheltered or wind-scoured terrain.  

     

    Example of wind slab avalanche in above treeline terrain

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    A weak layer of sugary (faceted) snow has been steadily loaded by several feet of new snow. This issue was most prominent in the Eddy Mountains, particularly on north-facing terrain near and below treeline. Last weekend, natural avalanches and multiple signs of instability were observed three days after the weak layer was buried. Since then, signs of instability and the likelihood of triggering have decreased.  

    This remains a low-likelihood, high-consequence hazard. We will continue monitoring it for one more day before likely removing it from consideration. To assess reactivity, dig to locate this layer and conduct stability tests.

Avalanche Discussion

Winter conditions are in full force. While a recent cycle of high avalanche danger has passed, another round of heavy snow and strong winds is expected in the next 24 hours.

A poor visibility tour of below-treeline terrain yesterday revealed no glaring red flags, but conditions near and above treeline remain uncertain. Avalanche danger persists, even without obvious warning signs—stay alert. Our 28-day January dry spell ended last weekend, and since then, at Bunny Flat (6,950 feet), new snow on top of the old measured 42 inches. At our Old Ski Bowl weather station near treeline (7,800 feet), storm total measures 58 inches. At Castle Lake, 34 inches and Mt Eddy, 38 inches.

Deep snow is a serious hazard. These conditions have led to 911 calls from "stuck, soaked & stranded" snowmobilers. Choose your partners wisely and match terrain and conditions to skill level. Skiers, beware—tree wells are man-eaters right now and extremely dangerous: deep, hollow, and potentially fatal.

Avalanche risks remain elevated and the recipe is there. Stay vigilant!

🚧 Everitt Memorial Highway and Castle Lake roads are CLOSED with no estimated reopening.

Régions couvertes