Gothic PM weather update

CB Avalanche Center2018-19 Observations

Location: Paradise Divide Area
Date of Observation: 01/06/2019
Name: Billy Barr

Subject: Gothic PM weather update
Aspect:
Elevation:

Avalanches:

Weather: Since 7 a.m. sweep this morning there was 7½” new snow with water0.46″ and snowpack at winters deepest of 39″ (there was an additional 2″ snow 0.15″ water from 3-7 a.m. today). At sunset wind kicked up after being calm all day and is now moderately strong with little snowfall any more. When wind started I could hear slides running off Gothic Mountain.

Snowpack:
Photos:

Coon Basin Slide

CB Avalanche Center2018-19 Observations

Location: Crested Butte Area
Date of Observation: 01/04/2019
Name:

Subject: Coon Basin Slide
Aspect: South East
Elevation:

Avalanches:

Coon basin slide seen from lower red lady ridge. Already reported but just another interesting angle showing the skin track that triggered the slide.

Weather: Sunny, temps around 25-30 degrees

Snowpack: Wind&sun affected layer on top of a soft layer.

Photos:

Large slab avalanche and weak layers

CB Avalanche Center2018-19 Observations

Location: Kebler Pass Area
Date of Observation: 01/05/2019
Name: Zach Kinler

Subject: Large slab avalanche and weak layers
Aspect: North, North East, East
Elevation: 10,000′-10,600′

Avalanches:

See picture below of suspected snowmobile triggered D2 slab avalanche from this morning. The avalanche was in part of the path of a larger natural slide that occurred on 12/5. The crown appeared 3-4 ft deep from a distance and ran ~250-300ft. It broke in old snow.

Weather: Increasing clouds with high ~0C, moderate WSW winds on a quick trip up to Scarps Ridge. Light and variable winds below ridge top.

Snowpack: Punched a couple holes on an East and North aspect below tree line to test our mid December weak layers before our next loading. These Surface Hoar and Faceted Crystal layers are clearly visible while excavating the pit and produced fractures in long column tests with no propagation within the standard test. Additional loading steps and prying of the slab produced planar fractures in all tests. The overlying slabs are still very soft at F- 4F- which may be limiting propagation at this point. See pictures below with a few test results.

Surface conditions were 5 mm SH laying flat on East and 10 mm upright SH on North which look to get buried tomorrow.
Photos:

PP obs

CB Avalanche Center2018-19 Observations

Location: Paradise Divide Area
Date of Observation: 01/05/2019
Name: Joey Carpenter

Subject: PP obs
Aspect: North East, East, South East, South
Elevation: 9800-11500

Avalanches:

Multiple loose snow avalanches observed throughout the valley, especially on steep solar aspects. Photo of debris from 3 loose snow avalanches on steep SW facing terrain. R1D1.5. Not big enough to fully bury but certainly enough to carry.

Weather: Prior to sun making it to valley bottoms, inversion held temperatures below 0F. Rapid warming quickly brought temps into mid 30s. Low, flat clouds filtered in throughout the day. Winds went from calm to ~10mph by 2pm. No snow transport observed.

Snowpack: 2-3mm surface hoar observed between 9800-10800ft on all aspects we traveled. Intense solar radiation cooked SE, S off by midday. E, NE preserved and will presumably be buried by incoming storm. HS @ 11.5k E aspect 160cm. S, SE aspects held solid 2cm crust from yesterday even near upper elevations. During intense morning sun, the crust began to moisten and refroze as clouds moved in throughout the day.

Photos:

BTL Loose Dry

CB Avalanche Center2018-19 Observations

Location: Crested Butte Area
Date of Observation: 01/04/2019
Name: CBPSP

Subject: BTL Loose Dry
Aspect: North
Elevation: 10,300′

Avalanches:

Weather: Clear calm wind, with temperatures in the high 20’s.

Snowpack: Went in search of Dry loose avalanches BTL. We were able to trigger some small .5 and smaller slides in steeper terrain features that had not yet been effected by skier traffic. In isolated areas the snow we got to move would entrench the entire snow pack due to its weak nature. The HS was on avg. 60 cm very weak and faceted on N facing terrain BTL.
Photos:

South Surface Hoar

CB Avalanche Center2018-19 Observations

Location: Kebler Pass Area
Date of Observation: 01/03/2019
Name: Will Nunez

Subject: South Surface Hoar
Aspect: South East, South
Elevation: 11,000

Avalanches:

2 small-med loose avalanches in RLB

Weather: Cold in the am, light to mod winds from the N NW, Strong solar gain in the pm. Clear all day.
Snowpack: HS ranged from 80-140Ccm
Surface Hoar is still present on all SES aspect and elevation, with strong solar it could have been melted away forming a sun crust.
Buried surface hoar still exists in the upper layers of the snow pack, reacting and planner to shovel tilt tests. SH 16cm and 30cm down, both reacting and planner. There’s still a PS structure but the basel facets are rounding and non reactive to ECTs and CTs.

Photos:

Loose Dry BTL

CB Avalanche Center2018-19 Observations

Location: Crested Butte Area
Date of Observation: 01/03/2019
Name: Alex Tiberio

Subject: Loose Dry BTL
Aspect: North
Elevation: 11,000

Avalanches:

Loose dry sluffing on every slope slope over 35 that we traveled on

Weather: Bluebird day
Snowpack: Poking around N facing shady terrain in Virginia Basin, Persistent Slab structure present in spots and nothing but weak snow in others spots. Significant surface hoar present

Photos:

Sluffy

CB Avalanche Center2018-19 Observations

Location: Crested Butte Area
Date of Observation: 01/02/2019
Name: Evan Ross

Subject: Sluffy
Aspect: North East, East, South East
Elevation: 9,000-12,000

Avalanches:

Long running loose snow avalanches accumulated mass as the gouged into the weak snowpack.

1 sluff/slab thing that propagated a little wider, D1.5. 10,100ft NE.

Weather: Clear and mostly calm. Some light winds just able to move snow from the north side of the ride to the south side at times, above treeling.
Snowpack: Kicked it off on E ATL. Snow on the exposed ridge was fluffy, how often does that happen? Some sluffing in the new snow otherwise nothing notable. Same slope as in this picture from 12/29. Weak layers are present, but all the ingredients where not there for a slab release on this specific part of the slope. This slope had seen a shallow but fairly wide natural windslab on 12/30 likely failing on the upper most weak layer.

Moved to more SE NTL by 1pm and those slopes had become moist at the surface. The structure on these slopes was fairly simple, with generally soft and faceting snow over a crust over more weak faceted snow. Other then the curst there wasn’t really anything to propagate . Steeper slopes the crusts was stronger of course and lower angled slopes is where the crusts where more brittle and collapsible. Somewhere with more of a slab, like wind-loading on this structure, would have been more concerning.

NE 11,300-9,000ft. Steep, aggressive, mostly open BTL type terrain. Sluffing was the primary issue. Small sluffs where running long distances and accumulated mass as the gouged into the weak snowpack. Skiing a steep ridge feature, the lee side of the feature produced shooting cracks in a couple places that didn’t propagate much. Was able to get a larger D1.5 slab/sluff or slub thing to release at about 10,100ft.

Photos:

Red Coon Basin Remote Trigger D1R1

CB Avalanche Center2018-19 Observations

Location: Kebler Pass Area
Date of Observation: 01/02/2019
Name: Will Nunez

Subject: Red Coon Basin Remote Trigger D1R1
Aspect: South East, South
Elevation: 11,000

Avalanches:

Shooting cracks off the ski tip resulted in a remote triggered D1R1 200 ft away. The crown was 10-30cm, running on the preserved SH Year Years storm interface planer and F 4F. (CBAC Note: Slope estimated at 110 degrees ESE)

Weather: Clear Cold and light to mod wind NW
Snowpack: HS ranged from 60-150cm, 1-3mm SH was present and preserved on all S-SE aspects and elevations.
PS structure was still presented but resistance to hand shears.
Unreactive shallow wind slabs on S-SE Above Tree line 4-10cm.

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Photos: