Snow Surface and Structure

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 03/05/2016
Name: Evan Ross
Subject: Snow Surface and Structure
Aspect: North East, East, South, South West
Elevation: Mostly BTL/NTL

Avalanches: No avalanche problems observed
Weather: Broken skys or partly cloudy to mostly cloudy during the day. Still strong solar/warming snow surfaces and warm temps. Was at ridgeline only for about 20min and winds were light from the south to southwest.
Snowpack: Snow surfaces are highly variable through terrain and across slopes. The most concerning surfaces where on sheltered shady slopes that had near surface facets. Otherwise snow surfaces range from wind packed to some forms of ice lens, or melt form. Many of these surfaces are also wind rippled. See pictures for more details.

NE, 11,250, 25 degree slope. Wind packed particles over striated facets. HS around 100cm.

NE, 11,250, 25 degree slope. Wind packed particles over striated facets. HS around 100cm.

 

NE, 11,200, 32 degree slope. Just 50 feet below the above picture. Wind effected snow surface with mostly wind packed particles at the surface, but some small NSF in very small pockets between the wind effect and on the surface. This soft wind crust was resting over some faceted particles but the overall snowpack structure was generally not to concerning. Big variability from concerning structure to non concerning structure is the take home.

NE, 11,200, 32 degree slope. Just 50 feet below the 1st picture in this post. Wind effected snow surface with mostly wind packed particles at the surface, but some small NSF in very small pockets between the wind effect and on the surface. This soft wind crust was resting over some faceted particles but the overall snowpack structure was generally not to concerning. Big variability from concerning structure to non concerning structure is the take home.

 

Protected NW aspect, 10920', Slope 35, HS 165, boot pen 30cm. 1cm NSF over over a mostly rounded snowpack and generally structureless down to observed depth of 60cm.

Protected NW aspect, 10920′, Slope 35, HS 165, boot pen 30cm. 1cm NSF over over a mostly rounded snowpack and generally structureless down to observed depth of 60cm.

 

Dusty snow surfaces on south easterly facing slopes. Structure: At 10750', SSE aspect, HS 90cm, 5cm boot pen at 12:45pm. A 22cm MFcr was over 4F moist snow below. Isothermal throughout structure. At 9,700' SW aspect, HS 55, slope 34 degrees, boot pen 5cm. 34cm P+ hard MFcr over F hard wet snow below.

Dusty snow surfaces on south easterly facing slopes.
Structure:
At 10750′, SSE aspect, HS 90cm, 5cm boot pen at 12:45pm. A 22cm MFcr was over 4F moist snow below. Isothermal throughout structure.
At 9,700′ SW aspect, HS 55, slope 34 degrees, boot pen 5cm. 34cm P+ hard MFcr over F hard wet snow below.

 

Southeast aspect NTL, wind effected snow surfaced turned to melt forms. Isothermal snowpack.

Southeast aspect NTL, wind effected snow surfaced turned to melt forms. Isothermal snowpack.

 

Dusty snow surfaces ATL on easterly and north easterly terrain in the paradise divide zone.

Dusty snow surfaces ATL on easterly and north easterly terrain in the paradise divide zone.

 

Shinny snow surfaces on north easterly NTL terrain.

Shinny snow surfaces on north easterly NTL terrain.

Mountain Weather 3/5/2016

CB Avalanche CenterWeather

Date: 03/05/2016

Our weather continues to remain warm and dry today with high clouds overhead. Believe it or not, there is a change in this weather pattern coming tomorrow, as a low pressure system moves towards the west coast. This system will be pushing moisture over the western US bringing us increasingly cloudy skys on Sunday and the chance for some snow. Temperatures Sunday remain mild so we’ll likely not see much snow accumulation until a cold front arrives sometime around Sunday night. With southwest flow, increased available moisture, and decreasing temperatures we should have some new snow accumulations to talk about on Monday morning. Snow showers will decrease on Monday before stormier weather returns around Tuesday.

Mountain Weather 3/4/16

CB Avalanche CenterWeather

Date: 03/04/2016

We’ll see a mix of partly cloudy skies and warm temperatures over the next 24 hours as a weak ridge passes overhead. It now looks as though the dry and clear slot will pass overhead tonight, and clouds will begin to thicken tomorrow morning ahead of the next system, putting a damper on Saturday’s corn harvest. A large Pacific trough moves onshore on Sunday, but unfortunately it closes off and the energy splits around Colorado. Our best shot at snow is a shortwave trough leading this system. We’ll see potential for light snow showers developing on Sunday at the front end of the shortwave, followed by a boost in snowfall on Sunday night into Monday as the associated cold front sweeps through. We could see 4-8″ by Monday evening, although we’ll refine those numbers as this system gets closer.

White Rock Mtn

CB Avalanche Center2015-16 Observations

Location: Paradise Divide Area
Date of Observation: 03/03/2016
Name: Zach Guy
Subject: White Rock Mtn
Aspect: South West, West, North West
Elevation: 9,500-13,400 ft

Avalanches: No recent avalanche activity observed. Plenty of crowns from Feb 1 cycle still visible, and a handful of old wet loose, some reaching D2 in size that gouged to the ground, from our mid-February warm-up on southerly aspects N/BTL above Copper Creek. One D1 wind slab on a crossloaded N aspect above treeline on White Rock that probably ran around 2/23.
Weather: Warm temps. Light westerly winds. Thin few clouds this morning increased to thin overcast by late afternoon.
Snowpack: W/NW slopes near treeline were all weak facets, ski pen occasionally to the ground. Thin, unsupportive melt-freeze crusts emerged on due west NTL. Surfaces are variable above treeline; lots of pencil or knife hard wind board, some soft sastrugi, meltfreeze crusts starting on W aspects and becoming thicker towards SW. Very small surface facets above these surfaces on northerly tilts. A lot of NW facing slopes ATL are blown out to dirt. I jumped onto a SW slope below treeline in the afternoon. The top few inches were very wet, but the snowpack was still supportive. No signs of instability.

Mountain Weather 3/3/16

CB Avalanche CenterWeather

Date: 3/3/16

Beautiful mountain weather is in store for today as a transitory ridge brings sunny skies with a few thin clouds and warm temperatures to the Elk Mountains. Clouds will increase again tonight as another shortwave rides north of our area. We should see a final brief clearing on Saturday morning as we happily wave goodbye to the east-bound high pressure ridge that has reigned supreme over our weather for the past month. The ridge’s departure opens the doors to a more active and snowy pattern. The first decent chance of snow arrives on Sunday.

Facet Sluffs

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 03/02/2016
Name: Steve
Subject: Facet Sluffs
Aspect: North East
Elevation: 11,700-9,400′

Avalanches:
Weather: Broken skies after a brief snow squall between 8 and 9 am. Near but below freezing temps with a cold moderate to strong wind blowing from the SW but swirling and sometimes blowing upslope from the NE
Snowpack: Skier triggered a couple small facet sloughs in steep terrain. Otherwise no avalanche problems found as there is very little strength in the snowpack. Ski pen from 0-20cms. Snowpack depth averaged 120cm, but previously avalanched areas had as little as 35cm.
Not nearly enough new snow to form windslabs. Crusts did not soften even at low elevations.

No significant avalanche problems

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 03/01/2016
Name: Evan Ross
Subject: No significant avalanche problems
Aspect: North East
Elevation: 11,100-9,400

Weather: Scattered to broken cloud cover. Mild temps
Snowpack: skier triggered a few very small facet sloughs in steep terrain. Otherwise no avalanche problems found. Ski pen around 5cm on 99% of slopes traveled. Some snow surfaces were a form of sun/temperature/wind/rain very soft crust, over 4f snow below, while others were just weak near surface facets over similar snowpack structure below. HS dropping, in the 70-80cm range.

No new avalanche observations looking around the range form the Gothic road area. Just brown snow problems.

Mountain Weather 3/2/16

CB Avalanche CenterWeather

Date: 03/02/2016

Shortwave disturbances will continue to pick away and nudge at the dominating Western U.S. high pressure ridge through the rest of the week, attempting to change or stagnant and dry weather pattern. A pattern change now appears to be on its way for next week. For today, the next shortwave will brush to our north, bringing mostly cloudy skies, gusty winds, and the chance for a few snow flurries. Weak ridging rebuilds tonight with enough embedded moisture for some high level clouds tomorrow.

Weak and unreactive snowpack

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 03/01/2016
Name: Zach Guy
Subject: Weak and unreactive snowpack
Aspect: North
Elevation: 10,000-11,800

Avalanches:
Weather: Scattered to broken cloud cover. Mild temps. Moderate winds with no transport.
Snowpack: On a north aspect near treeline, the snowpack was generally shallow (due to wind scouring and/or previous avy activity) and very weak, lacking any persistent slab structure presently, but will be concerning if we get a future load. Facets ranged from 1mm to 4mm in size, mostly fist hardness, capped by a breakable wind crust; trapdoor skiing and pole plants easily to the ground. No signs of instability except minor facet sluffs and a few pizza box wind slabs in gulley features.

Cement Creek after 5 p.m.

CB Avalanche Center2015-16 Observations

Location: Cement Creek Area
Date of Observation: 02/29/2016
Name: ADB
Subject: Cement Creek after 5 p.m.
Aspect:
Elevation:

Avalanches:
Weather: Calm. S-1 snowfall. 2/29/16 5 to 645 pm.
Snowpack: Trace of graupel to <1 cm of new snow