Location: Crested Butte Area
Date of Observation: 12/16/2018
Name: Joey Carpenter

Subject: NE CB Zone Obs
Aspect: North East, South, South West, West
Elevation: 9200-12200

Avalanches:

1 small windslab that ran earlier in the week S of whiterock. SS-N-R2-D1
E face of Baldy. SS-N-R1-D1. Earlier in the week and observed from very far away.
Multiple point releases from steep SE facing terrain, also earlier in the week. A few did pick up enough snow to knock you of your feet.

Weather: Clear, calm and warm.
Snowpack: NE BTL. Too many collapses to count. All relatively small as the slab below 9.5k on NE facing terrain is eroding. Isolated terrain features did produce 20-50 foot cracks under a skiers weight. Overall in this area, at this elevation band, there is minimal slab structure and a weak, unconsolidated snowpack. However, it does seem seem possible to produce avalanches in isolated terrain features BTL where the slab is more resilient.

S, SW, W BTL spx is thin <50cm and weak. Steeper isolated features that received windloading last week did produces small whumpfs and cracks. Barely enough coverage to move through terrain below 10k. NTL collapses on isolated terrain features became more pronounced. The overall snowpack in this area averaged 60cm except on slopes steeper than 30 degrees that are predominantly S facing. The spx on these solar aspects steeper than 30 degrees was surprisingly thin and weak. Overall in the NTL elevation band the slab structure is intact but weakening. N/ATL (~12.2k) spx averaged around 75cm excluding scoured terrain. Collapsing near the ridgeline was substantial and propagating well away from our skintrack. Stability tests produced: CT12SCQ1, ECTPV14Q1 x2 on 2-3mm facets that made up the bottom 15cm of the spx. The slab resting on the facets was 1F in hardness and still very much intact. Failures were quick and clean. Newer snow near surface F hardness.

Photos:

Location: Kebler Pass Area
Date of Observation: 12/15/2018
Name: IG

Subject: Irwin Cat Ski Obs
Aspect: South West, West
Elevation: Below and near treeline terrain

Avalanches:

Lone Wolf- Shallow wind slab did not run down to the 11/22 interface

Castle Valley Left- Averaged an 80cm crown. Down to the facets near the ground. Took out the 11/22 interface.

Lone Wolf SS-AE-R1-D1.5-O FC (25cm x 15m x 175m)
Castle Valley Left SS-AE-R2-D2-G FC (80cm x 20m x 250m)

Weather: Clear, Calm winds down low with moderate gusts up high out of the west. High temps 34 @
10,200′ & 24 @ 12,000′.
Snowpack: PS structure still present in UUWW. Shallow snowpack on average less than 90cm. Single
hand shots are effective to ground in the upper upper west wall in most places.

Photos:

Location: Crested Butte Area
Date of Observation: 12/15/2018
Name: Steve Banks

Subject: Gothic Obs
Aspect: East, West
Elevation: 9,500->10,600

Avalanches:

No new avalanches observed. Some small WL dribblers steep SW slopes ATL

Weather: Mostly clear skies with warm temps and calm winds. Some high cloud passage from 11-12:30 accompanied by light westerly winds. High temp hit +2 C.
Snowpack: Morning surface hoar destroyed by sun but preserved and up to 4mm on shady slopes. SE-S-SW slopes BTL have a crust up to 3 cms thick. On these aspects we also found a thin, soft crust 6-10 cms below the surface with near crust facets above and below. This layer showed clean shears with shovel tilt tests.
Several large collapses BTL on West and East facing aspects between 9,600-10,000’ on low angle slopes. Some cracks went to the ground/basal facets. HS 55-70 cms.
On East aspects near 10,000’ snow pits revealed Persisten Slab structure with 4F to 1F slabs resting over 4F to F hard facets near the ground (14 cms of 3-4 mm facets) with ECTP 16 SP in a pit with HS of 78 cms. A pit in an adjacent slope got repeated ECTX scores with 100 cm snowpack. However on this location, prying on the column showed a very clean shear down 45 cms on the interface moving from 4F to 1F with small .5 mm facets.
In a nut shell: the persistent slab problem is there on shady slopes below treeline and is becoming difficult to trigger in some places, easier in others.

Photos:

Location: Crested Butte Area
Date of Observation: 12/15/2018
Name: Zach Kinler

Subject: Bustin’ out of that Inversion
Aspect: North, North East, East, South East, West, North West
Elevation: 9,000′-11,000′

Avalanches:

No recent avalanches observed.

Weather: Splendid, cold in the valley, quite pleasant above 10,000′ with high temps at or just above freezing, lots of sun with only a few passing high clouds. Calm winds with no snow transport observed.
Snowpack: I travelled up Wolverine Basin to the start zone of Right Chute able to observe many aspects. Was paying close attention to possible Surface Hoar buried in the top of our snowpack as well as Persistent Slab structure in both areas that slid and areas that did have not slid.

Surface Hoar was observed in open areas from shady West-North-East. The most preserved crystals (pictures) were found on North aspects that have remained very cold and were up to 6mm; other aspects that may get a bit of sun were a mix of decomposed SH and DFs with aspects South of East having a mix of Melt Forms and decomposed SH. As the slope tilted to SE, this layer was 1cm breakable crust with small facets above and below. This layer was only 6-7 cm from the surface in this zone so it is hard to say what may happen between now and our next storm.

Although I consistently travelled on snow that presented as slab over weak, I experienced no cracking or collapsing, even clicking out of skis and punching into the weak layers with my boot in untracked terrain, with no results. Pit (picture) in the Right Chute start zone, N aspect @ 11,000′ revealed 3-4 mm basal facets under a 5cm P+ crust that were still very weak (F hardness) but rounding and not reactive in a long column test(ECTX).

Poked a few slopes that slid after the Thanksgiving cycle and now hold only F-4F- slabs showing no signs of instability in this zone.

Lots of settlement cones(picture) up to 30cm, a result of recent warmer weather.

Photos:

Location: Crested Butte Area
Date of Observation: 12/15/2018
Name: Evan Ross

Subject: Colorado Backcountry Avalanche Level 1
Aspect: North East
Elevation: 9,600-10,800

Avalanches:
Weather: Rather delightful. Few high thin clouds and warmer temperatures climbing out of the valley. Calm winds at our elevations.
Snowpack: The snowpack at lower elevation was simply weak with little structure still intact, HS around 50-60cm. As we got higher in elevation the snow hight increased to about 75cm at 10,600ft. Here strong over weak Persistent Slab snowpack structure was becoming much more obvious as we probed through the snowpack. Just as quickly as the snowpack hight had increased, we had also increased our slope angle to around 35 degrees and observed the snowpack drop in hight to about 50-60cm and the PS structure disappeared. Just looking at the slope it was hard to see any difference, however getting up close and personal with the slope we could tell it had previously avalanched earlier this winter. We saw no obvious signs to instability, but also didn’t push our slope angles where we found the PS structure.

Location: Crested Butte Area
Date of Observation: 12/14/2018
Name: Steve Banks

Subject: Gothic Obs
Aspect: West
Elevation: 9500

Avalanches:

No recent avalanches were observed.

Weather: Clear and Sunny, little to no wind, high temps near freezing.
Snowpack: Mostly travelled on the road to Gothic. Observed small 1-3 mm surface hoar in the valley floor. In untrammeled terrain low in the valley West facing we received multiple loud collapses. There were areas of wind stiffened surface snow and evidence of previous wind drifting and loading (including some scree loading)

Photos:

Location: Paradise Divide Area
Date of Observation: 12/13/2018
Name: Zach

Subject:
Aspect: North East, East, South West
Elevation: 9,000′-11,000′

Avalanches:

One new slide observed on East Cinnamon ~12,000′. Propagated ~150m across the slope and ran 300+ m out of sight.

Weather: Long underwear and a down jacket were greatly appreciated. Sunny skies, Cold with NW to NE winds, light-moderate with gusts and enough to transport small amounts of snow from time to time below tree line. Light loading off of larger peaks and ridge lines.
Snowpack: See picture of weekly profile from the Elkton Study Plot for a snapshot of that location.

On a search for Surface Hoar, Shovel Tilt tests at the plot site and at two NE open slopes BTL revealed easy results @ 10cm on Preserved Stellars(picture), No Surface Hoar found in any of these locations.

On Anthracite Mesa, very little windslab growth as strong NE winds were scouring snow in the open bowls and depositing it on the flats at ridgeline. No collapses or cracking was observed as the PS structure remained quiet today.

Photos:

Location: Kebler Pass Area
Date of Observation: 12/13/2018
Name: Eric Murrow

Subject: Kebler Pass Buried Surface Hoar
Aspect: North, North East, East, South East, South
Elevation: 10,000′-11,500′

Avalanches:

Two fresh avalanches were visible on Mt Owen. Could not see crowns, but presume them to be wind slabs. Estimate to be D1.5.

Weather: Brrrrr it was a cold morning out there . Winds were light with moderate gust out of NW at treeline. Small amounts of transport were happening during tour.

Snowpack: Kept moving through out the tour to stay warm, but performed at couple quick test at surface. In two locations, on at 10,600 and 11,000, both NE aspects and open meadows I found buried surface hoar about 10cm down.
Other notable finds were drifts up to 14″ deep immediately below ridge top on south/southeast aspects. Stomping just below ridge top produced minor cracking, approx. 5 feet. Ski cut same slope on way down without any result. Drifts dissipated quickly as you moved down slope. There were several large drifts at the ridge top that were 18″ deep or more, got one to collapse with three people standing on drifted whales at ridge top which caused a small fresh cornice to break onto a southeast slope.

Photos:

12/13 Fresh slides on Mt. Owen

Location: Crested Butte Area
Date of Observation: 12/13/2018
Name: billy barr

Subject: Gothic Townsite 7am Obs
Aspect:
Elevation: 9400

Avalanches:
Weather: Light snow Wed. afternoon with 1½” with 0.10″ of water and was looking OK but then wind came late day and shut off snow with just 1″ snow and 0.07″ water overnight while clearing. Wind stopped around 4 a.m. and it has dropped to -03F so far. Snowpack at 23½” and has been holding steady with the light snow. Now clear and calm. billy
Snowpack:

Photos:

Location: Cement Creek Area
Date of Observation: 12/11/2018
Name: Evan Ross

Subject: Cement Creek Check In
Aspect:
Elevation: 9,000-12,000

Avalanches:

Plenty of old avalanches to be seen from earlier this season at ATL/NTL/BTL elevations. Though, those avalanches are getting covered up and more difficult to detect with more recent snow and wind. Old Persistent Slab avalanches could be seen on west to north to easterly aspects. Southern aspects only had some old, smaller Wind Slab avalanches in the alpine.

Weather:
Snowpack: Traveled Cement Creek Rd to the end of the valley at 12,000. Not enough snow to want to get off the road via snowmobile and by the looks of things the skiing options were slim too. No signs of recreational travel this season in the upper Cement Creek area. In the lower Cement Creek drainage there wasn’t really enough snow for skiing in avalanche terrain. Moderate avalanche danger would hold for the area given heightened avalanche danger on specific terrain. That specific terrain would be wind-loaded areas. On the lee sides of ridgelines and in cross loaded terrain or gully features. Given what we know about the weather history and observations in other parts of the CBAC forecast area, these wind loaded terrain features would be suspect for the Persistent Slab avalanche problem as is currently highlighted on the avalanche bulletin.

Photos: