Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

The daily wet loose cycle is on, and isolated but very large slabs continue to be reported. Give yourself plenty of extra room, well away from larger slopes and looming cornices in the chance one does release.  Chances remain to trigger a small, soft wind slab at higher elevations with a round of easterly winds drifting snow at ridgetops.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    With 4-6" of newer snow resting on a crust and warming temperatures, loose slides may run during the heat of the day as snow surfaces melt. Watch for roller balls and tree bombs as indicators that the snow is becoming moist. For the most part, these should be small, but in larger terrain they could entrain more snow than you'd want to mess with. Exercise caution near terrain traps like steep slopes above cliff bands and tight gullies.

    With the warming trend, cornices are beginning to warm, and could break off during the daytime. Stay out from underneath any large cornices off ridgelines.

    (3/15/2023)

    Large wet loose avalanche that likely ran on March 13 or 14th.

    Photo: Matt Primomo

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–3

    Small, soft wind slabs could be triggered in isolated areas on Friday. Easterly winds on Thursday were observed transporting snow near high ridgelines in the zone. Look for drifting patterns and textures, and feel for slightly stiffer snow as you gain elevation. Look for signs of instability like cracking  and use small test slopes to check for instability.  Steer around drifts on steep and/or unsupported wind drifted features.

    The monsters in the basement warrant a special note. A few isolated, but very deep (up to 10ft deep) slabs have been observed over the past week. While the chances of actually triggering one of these is probably very small, large loads like snowmobiles, big cornice failures, or perhaps a warming event could potentially still do it. If any very large slides did occur, they would run much further than you might expect, so best to add in lots of buffer room well away from large steep slopes while your out in the mountains.

    (3/15/2023)

    NE aspect at appx 5,300ft east of the Swath. This pocket was estimated to have occurred March 10th or 11th.

    Photo: Matt Primomo

Avalanche Discussion

Expect sun and warmer temperatures to become the main influencer of our snow and avalanche conditions going into the weekend. Temperatures are on the rise for, and sun should melt snow surfaces on all aspects except for northerlies. On Wednesday I found up to 6" of new snow resting on a supportable sun crust on SE to SW aspects on Lichtenberg. Wind had drifted some snow on the exposed shoulder, but drifts were soft I didn't observe much cracking. Observers reported natural wet avalanches to size D2 on steep, sunny slopes and some cracking in wind-stiffened snow near and above treeline on Tuesday. Another 6-8" of snow fell on Monday with snow level up to 3,500ft, and Brooke and I observed a natural wet loose cycle occuring during the day. Some notable large slides occurred off the south side of Lichtenberg and Rock Mountain. 

Another very large, deep slab release was noted from the West Face of North Chiwaukum on Thursday. This may have run  during a similar time frame as the others below on the 10th or 11th. Observers reported a couple of very notable avalanches over the weekend. A very large D3 natural avalanche occurred on the north side of Rock Mtn, likely on the 10th.  The crown was at 6,750ft, NE-NW, estimated at 6-10ft deep, 500ft wide and it ran approximately 1800 vertical feet. Two similar D3 avalanches were reported from NW aspectsabove treeline on Cannon Mtn in the neighboring East Central zone. These were suspected to have run on the Valentines Day Crust, buried in mid February but we haven't been to a crown to confirm. Between 2/28-3/6 we received reports of triggered avalanches that likely ran on the Valentines Day crust. On March 7th, I dug a profile on an adjacent slope to one of these slides on a SSW aspect below Skyline Lake. This crust is now 3-6 feet below the surface and triggering of an avalanche on it would be difficult, but could be very large and destructive.

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