Wet snow obs below treeline

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/14/2017
Name: Zach Guy
Subject: Wet snow obs below treeline
Aspect: North East
Elevation: 9,000 – 9,600 ft.

Avalanches: See photos. A number of shallow loose snow avalanches (both dry and wet), skier and natural triggered on southerly aspects, initiated by solar warming. D1 in size, involving just the recent storm snow. One D2 slab avalanche on NE aspect above treeline of Mt. Axtell, probably ran towards the end of the last storm.
Weather: Clear, calm, mild temps.
Snowpack: On NE aspects BTL, we found a drying, refreezing, stabilizing snowpack. See photo.
At 9,000 ft. Water front had advanced 30 cm and had percolated to, pooled, and now refrozen on an interface 55 cm deep (1/19 interface?). The upper 20 cm is now refrozen clusters or dry storm snow, leaving about 10 cm of very wet grains insulated 20-30 cm deep and capped by a refreeze that won’t break down on this shadier aspect.
At 9,600 ft, there were no wet grains remaining in the snowpack; a series of soft melt-freeze crusts in the upper snowpack.
The biggest concern at both of these locations is the thin layer of low density stellar dendrites above the soft melt-freeze crusts at the surface. This layer will quickly facet into our next weak layer over the next few days on shadier aspects where it doesn’t get cooked.

D2.  NE aspect ATL of Mt. Axtell
NE aspect at 9000 ft.  Wet grains refreezing.
Skier triggered D1 wet loose, S/SE near treeline.
Loose snow avalanches off of Mt. Belleview.  S aspect ATL

Mountain Weather 2/14/2017

CB Avalanche CenterWeather

Date: 02/14/2017

It froze! #itreallybelowfreezing! That may be the first hashtag in CBAC’s weather forecast but I’m really excited about his. Crested Butte is in the single digits this morning while 11,000ft temperatures are in the teens. This will be the theme the week as a high pressure ridge builds. We’ll likely see valley inversions each morning and dry weather through Thursday. Today, wrap around flow from a low pressure moving southeast of Colorado is helping drag in some colder air from the north. Helping shield us from what could be a rapped warm up. Winds look to remain light out of the northeast with mostly clear sky today.

Leve 2 Class

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/12/2017
Name: Evan Ross
Subject: Leve 2 Class
Aspect: North East, East
Elevation: 9,500-10,200

Avalanches:
Weather: Sky: obscured in morning, overcast through the midday and obscured again in the afternoon.
Precip: S-1 to S1 in the morning, no precep in during the midday and S1 again in the afternoon.
Temp: 9,500ft 10:30am Tair 3c Sur 0, T20 -1, 2:30pm Tair 1c, Tsur -.5 T20 -.5
Snowpack: See form

snod

I saw a mosquito

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/13/2017
Name: Evan Ross
Subject: I saw a mosquito
Aspect: North East
Elevation: 9,400-11,200

Avalanches: Big roller balls on a few steep ENE slopes. Think these mostly fell out of trees rolling to larger size as the moved down the hill. These didn’t entrain any more snow. New snow to thick?

Debris piles below the east face of Gothic. Couldn’t see any slabs or crowns on the face, though light could have been better.
Weather: Sun poking through the clouds in the early morning, then overcast sky for the rest of the day. S1 snowfall began at about 4pm. Calm winds
Snowpack: Very little signs to instability, traveling across several steep slopes to 40 degrees. Snowpack was pasted in above 10,500ft with an inch or two of fluff form last night. Minimal sluffing in 40 degrees terrain. Above this elevation the 2/10 interface was down 25cm and dry with some graupel in the mix. No CT results on this layer or results while skiing. In the same area on a 35 degree slope, 1/19 SH was down 90cm. CT27 SP on the SH. SH is still 2-3mm tall but looks to be filled with rounded grains between the feathers.

Below 10,500ft the snowpack became very thick. Very northwest feeling shmooo. Bet it was still 0c through the new snow as observed in previous days down below the 1/10 interface that is moist, going on borderline wet for about 5cm. Hand pits produced more non-planner breaks. Ski tests showed no signs to instability.

Viewd a number of glide cracks across the valley at low elevations and on small terrain. This one stuck out a litle more. East aspect 9,500ft.

IMG_2742

Moist borderline wet 1/10 interface at 10,000ft on ENE aspect.

IMG_2741

Dry 1/10 interface on NE aspect at 10,500ft. 1/19 SH down 90cm.

IMG_2734

Cement Creek

CB Avalanche Center2016-17 Observations

Location: Cement Creek Area
Date of Observation: 02/12/2017
Name: ADB
Subject: Cement Creek
Aspect: South West
Elevation: BTL

Avalanches: On south slope around 35 degrees, triggered a shallow wet slough, that traveled about 150 feet. Must have been slow moving as observed it on second lap. Slope position was an inflection point between concave and convex.
Weather: Obscured skies and mostly calm transitioning to S-1 with calm winds and slowly dropping temperatures.
Snowpack: 4 inches of new dense snow in the last 24 hours.

Gothic Loose avalanche spectacle

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/12/2017
Name: Tim Brown
Subject: Gothic Loose avalanche spectacle
Aspect: North East, East, South East
Elevation: 9,400-10-400

Avalanches: Approximately a dozen natural avalanches (L-N-D1-2) ran on the east side of Gothic within a half hour period as the skies cleared slightly around 1pm. With limited visibility and debris running over cliffs, it is hard to say for sure that that these were loose rather than storm slab avalanches. However, they seemed dry, came out of very steep terrain and didn’t trigger any additional slabs on the aprons below the cliffs.

Also saw a SS-N-R2D1.5 in a cross-loaded shallow gully near treeline that looked a day old
Weather: Temps slightly below freezing all day, snowing lightly (S-1) with a few periods of S1, mostly overcast skies with a few short periods of high thin clouds and strong solar radiation, light winds from the south, no blowing snow observed
Snowpack: 25cm of moist storm snow is settling into a slightly stiffer slab than yesterday over a 5cm thick layer of moist 3mm clustered melt forms, but test slopes and compression tests produced no results on a SW aspect near 10,000′ near Avery. A similar storm slab was much more reactive to hand shears on an east aspect ~9,500′ near the trailhead where it was on a wetter weak layer of similar grains.

Gothic

Mountain Weather 2/13/2017

CB Avalanche CenterWeather

Date: 02/17/2017

The low pressure that was streaming moisture into our area on southwest flow has moved inland over the Mexico border and is now pushing that moisture into Colorado on south flow. South flow is going to leave us mostly high and dry today with mostly cloudy sky. The jet stream and main weather flow is north of Colorado leaving us in the no man’s land between these two weather features. This allows continued calm winds today. That low pressure will continue to move east creating up flow events in areas such as the Front Range. For us, we’ll see a drying trend this evening and a high pressure ridge building for the week.

Wet avalanches onto Hwy 135

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/12/2017
Name: Zach Guy
Subject: Wet avalanches onto Hwy 135
Aspect: East, West
Elevation: 8,000 ft.

Avalanches: Several full depth (~12″ deep) wet loose avalanches came onto the shoulder of Hwy 135, D1 to D1.5, near and north of Almont. Not sure when these ran, but they looked fresh.
Weather: Temperature was above freezing at 10 p.m. Foggy, no current precip.
Snowpack:

Gothic

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/11/2017
Name: Tim Brown
Subject: Gothic
Aspect:
Elevation: BTL

Avalanches: Heard one large natural avalanche rumbling down the East a Face of Gothic around 2pm, but poor visibility all day limited observations. No other cracking or collapsing on short and very soggy tour.
Weather: Intense snowfall over last 24 hours with periods of 1″/ hour (S3), Air temp 3 deg C at 1300, consistently obscured skies and light to moderate northerly winds without significant snow transport in the valley bottom.
Snowpack: 1pm on flat terrain @ 9,600′ w/ HS 230cm and PF 50cm: 25cm of moist storm snow tops 20cm of wet snow over a thin, moist crust and an otherwise nearly homogenous and mostly dry snowpack. Compression tests produced hard PC results down 25cm on 3mm clustered melt forms and down 45cm on a thin layer of .5mm moist facets under the crust. Percolating water is not pooling on the crust here. Found Jan 19th surface hoar layer down 85cm, but CTN on this layer and ECTX 150cm deep. 30cm thick wet slabs failed easily under skies but showed minimal propagation on 35-40 degree small, well-supported test slopes.

Layered

CB Avalanche Center2016-17 Observations

Location: Cement Creek Area
Date of Observation: 02/11/2017
Name: ADB
Subject: Layered
Aspect: South, South West
Elevation: BTL

Avalanches: No instabilities.
Weather: Mostly S1 precipitation with moderate and light winds. Winds didn’t transport ground snow.
Snowpack: Less than 2 inches/24 hours including today’s tour.
Hand pits on SW aspects:
1-2 inches of new snow on 2 inch wind slab. Below windslab, 3-5 inches of F hardness wet crystals on top of 2 inch 1F crust. Below were another 2 -4 inches of 4F snow.

Evidence and magnitude of this weeks winds? 2 to 6 inch snow globules littering some of the open slopes. Source: snow from aspens and spruce.