Date of Observation: 12/24/2022
Name: Phill Ott
Zone: Northwest Mountains
Route Description: AMR
Observed avalanche activity: Yes
Avalanches: An old hard slab in the Playground. Likely ran during the extreme wind event.
Photos:
5794
Date of Observation: 12/25/2022
Name: Zach Guy, Sierra Bishop, and Jack Caprio
Zone: Southeast Mountains
Route Description: Mount Emmons to 11,300′. We targeted southerly facing terrain in Racoon Basin and northeasterly facing terrain in Climax/Happy Chutes area.
Observed avalanche activity: Yes
Avalanches: We skier-triggered a pair of avalanches in Climax Chutes that started as facet sluffs but propagated wider as soft slabs once they started moving, entraining the entire snowpack (about 30 cm) to the ground, D1 and D2 in size. This path ran naturally around 12/6, so the old persistent slab structure was gone. We were surprised to see how wide the slabs propagated given that there was only 3″ or 4″ of soft, wind drifted snow above the faceted bed surface.
Weather: Partly cloudy skies, light winds, no precip.
Snowpack: In short, the snowpack is weak and ripe for another cycle with the forecasted storm. The snowpack is exceptionally weak on bedsurfaces of slopes that ran in early December: 2mm chained facets. We already got evidence of how touchy this layer will be from the slabs that propagated fairly wide today under only a few inches of soft, wind blown snow (4F). On southerly aspects, we got propagating results on the crust facet layer (12/20 layer) buried by a few inches of soft, windblown snow. We got a couple of collapses and shooting cracks near valley bottom on southerly aspects where recent wind drifting formed thin, hard slabs over these layers. On northerly slopes below treeline that haven’t already avalanched, slabs have faceted out and are unreactive in tests (ECTN M). Depth hoar is 4-5mm in size below a fist to 4F hard faceted midpack (1mm).
Photos:
5793
Date of Observation: 12/25/2022
Name: Evan Ross
Zone: Northwest Mountains
Route Description: NW Mountains, various aspects, BTL/NTL
Observed avalanche activity: Yes
Avalanches: While jumping around on a ridge, I triggered an estimated D2 avalanche off the NE side of the ridge. This avalanche released in early December facets and above the November facets. This appeared to be an old/hard wind whale at the top of the slope that would have been formed earlier this month during more southwesterly wind events. The entire snowpack in the crown was in various forms of the faceting process, except for the most recent 4″ on top. Despite the faceted snowpack, it was still 1F to 1F+ hard through most of the crown. Just slightly downhill of the crown, the snowpack was mostly weak and shallow, with just a little 1F left in the mid-pack. This was represented in the avalanche flank, and in recent travels on similar terrain. I suspect this old wind whale released and then flushed to the ground through the weak snowpack below.
Snowpack: Over the last few days traveling mostly in wind sheltered below treeline areas, there hasn’t been anything notable to report.
Photos:
5792
Date of Observation: 12/24/2022
Name: Zach Guy and Eric Murrow
Zone: Southeast Mountains
Route Description: Cement Creek and Upper Brush Creek near Pearl Pass, up to 12700′ on various aspects.
Observed avalanche activity: Yes
Avalanches: A handful of previous hard slab avalanches from the arctic blast, D1 to D2, on heavily drifted slopes, generally E to S NTL.
Weather: Calm to light ridgetop winds. Mostly cloudy with periods of light snow. 1″ to 2″ of new snow since yesterday.
Snowpack: The Cement Creek valley floor was not as heavily wind impacted as what I’ve seen in the East River and Slate River corridors. The snow surface remains soft and weak below treeline, ~1mm facets. Once we climbed to near and above treeline, the snowpack got blasted. Snow surfaces are heavily wind affected, ranging from sastrugi to wind board to hard slab. The inch or two of fluffy new snow with no wind affect is a notable potential weak layer to monitor, especially if it facets over the next few days. It’s very low density resting on top of firm, wind hardened surfaces and there was minimal wind drifting it around, so it’s widespread at the moment.
No signs of instability today, though we weren’t messing around on the most suspect, windloaded slopes.
Photos:
5790
Date of Observation: 12/23/2022
Name: Irwin Guides
Zone: Northwest Mountains
Route Description: Irwin Tenure, East Barkmarker to Sunny Shoulder zone.
Observed avalanche activity: Yes
Avalanches: Triggered two additional D2s w/ HE. Same character as yesterday, running on 6-8″ of FCs.
Hollywood & Vine HS-AE-R2-D2-O FC (35cm x 20m x 100m)
Land of the Lost HS-AE-R2-D2-O FC (35cm x 15m x 75m)
Photos:
5789
Date of Observation: 12/23/2022
Name: Harry Von Longshank
Zone: Southeast Mountains
Route Description: Toured from 9200′ to around 11,400′ in the SW end of the SE forecast zone. Traveled on mainly easterly aspects all day.
Observed avalanche activity: Yes
Avalanches: Well, as this particular area is relatively shallow, most of the observed avalanches occurred on leeward features on E/SE aspects which were loaded during the recent wind event (surprise, surprise). A couple crowns were still fairly sharp and easily visible from a distance, which leads me to believe most of them ran towards the end of the wind-loading. Most appeared to have only been the wind slabs failing somewhere mid-snowpack but I did observe one on a very sparce and rocky N aspect ATL which failed to ground and seemed to have carried virtually all the available snow about 800′ down into the basin.
Weather: Pleasant. Light winds at best and mostly sunny. Temps probably somewhere in the high teens and low 20s.
Snowpack: 40cm down low, ramping up to around 100cm at higher elevations in protected areas. Wind stiffened and slightly textured in the open. Ski pen was roughly boot top all the way up. It was talkative in open meadows and clearings in the trees. I was able to get some surprisingly loud rumbling collapses traveling through most low angle, open terrain.
Photos:
5788
Date of Observation: 12/23/2022
Name: Eric Murrow
Zone: Southeast Mountains
Route Description: HWY 135 avalanche obs on Whetstone
Observed avalanche activity: Yes
Avalanches: Three natural avalanches from the wind event above treeline.
Weather:
Snowpack:
Photos:
5787
Date of Observation: 12/23/2022
Name: Zach Guy
Zone: Southeast Mountains
Route Description: Roadside obs near CB.
Observed avalanche activity: Yes
Avalanches: D1 to D1.5 wind slabs in Racoon Basin and on small slopes near town from the wind event. See photos.
Photos:
5786
Date of Observation: 12/23/2022
Name: Zach Guy
Zone: Northwest Mountains
Route Description: Baxter Basin and Cascade Mtn, traveled on north, east, and south aspects to 11,700′
Observed avalanche activity: Yes
Avalanches: Nothing new today. A handful of small wind slabs at all elevations and one potentially larger avalanche off of the Shield on Emmons appear to have run during the arctic blast.
Weather: Few clouds, light winds, mild temps.
Snowpack: As is often the case with these extreme wind events, the terrain got ravaged and there appears to be far more wind erosion than loading from Wednesday night’s event. Lots of sastrugi and raised tracks on all aspects. Winds eroded down to the early December graupel layer in areas, which was buried about 50 cm deep a few days ago. Of course, there are some terrain features that caught the drifting snow and formed hard slabs, most commonly abrupt concavities or rollovers. Ski cuts and snowmobile cuts on numerous of these suspect features produced minimal signs of instability; one slope cracked. Probably the best news from all the devastation is that the near-surface facet layer that was quite weak and soft on the surface a few days ago has been destroyed in many areas because of the wind event. I found it still preserved in very sheltered trees below about 5″ of recent snow, and below sun crusts on southerlies where the winds hadn’t stripped the crusts away.
Photos:
5785
Date of Observation: 12/22/2022
Name: Eric Murrow
Zone: Southeast Mountains
Route Description: visible natural avalanches from town of Mount CB
Observed avalanche activity: Yes
Avalanches: Natural avalanche on East Bowl of Gothic and two on southeast aspects of Avery Peak.
Weather:
Snowpack:
5784
