Name: Billy Rankin
Title: Irwin Snow Obs
Location: Kebler Pass Area
Date of Observation: 11/26/2014
Elevation: 10,200′
Snowpack: Irwin Storm total was 23″ w. 2.1″ SWE. Storm board was 17″ HS: 29″. There was a widespread rime crust this morning around 3-4 mm thick
Name: Ian Havlick
Title: 2014/11/25
Location: Kebler Pass Area
Date of Observation: 11/25/2014
Aspect: South, West
Elevation: 10,500
Avalanches: n/a
Weather: S1-S3 snow throughout morning. definitely convective and orographic. light variable winds in all but the most open terrain where the local winds were moderate from the WSW.
Snowpack: 27″ settled snow on HS stake. 15″ settled storm total. 6″ new overnight. Stout MFcr on South and West aspects below treeline. couple pits showed failure under moderate loading steps just below MF crust mid-pack. cracking and one major collapse on below treeline, west-southwest facing slope, that was around 34 degrees in steepness.
Location: Paradise Divide Area
Date of Observation: 11/25/2014
Elevation: 9,300-11,300
Weather: On and off snow showers producing about 3” of new snow between 9:30am and 3pm. Obscured sky throughout the day with strong enough NW wind to refill some tracks throughout the day but not strong enough to notice the blowing snow.
Snowpack: Snowpack: Found some wind stiffened snow but didn’t find a wind slab problem on the NE terrain at ridgeline. So the take home observations were, where in the terrain traveled was the persistent slab active? The snowpack needed to be deep enough to have a strong enough mid-pack to produce propagating test results. The mid-pack that has any strength is the 11/13 to 11/15 storm sitting over weak facets from earlier this season. This set up can be found down to 9,000ft west of Crested Butte. In this area, about 10,800ft seems to be the elevation where this mid-pack starts gaining enough strength to produce propagating results in snowpack tests that represent the potential for a persistent slab avalanche. Below that average 10,800 elevation on NE aspects the midpack could collapse and would only produce very small radius cracks, or ECTX test results. Above that elevation a pit dug with a 115cm snowpack and 4f-1f mid-pack produced an ECT21 SC and produced other collapses while touring with large radius shooting cracks. Thus, representing areas that could produce a persistent slab avalanche given the right slope angle and terrain feature.
Weather Discussion: Since yesterday, 2-4” of additional snow fell around area bringing the prolonged storm totals to 15-20” of snow since Saturday, with 1.5 to 1.8” of water equivalent. Westerly winds have continued to remain elevated, with most remote weather stations showing gusts in the 25 mph range over the last 24 hours. Today, snow showers will gradually diminish by early afternoon as high pressure works into the area today, and takes hold through the weekend.
High Temperature: 25-30º
Wind Speed (mph):10 – 20 mph
Wind Direction: West
Sky Cover: Overcast becoming clear
Snow (in): Trace-1″
Weather Outlook: The extended outlook looks mild and sunny through Thanksgiving, but another Pacific storm is taking shape and could bring another round of significant snow early next week.
Tomorrows Temperatures: 20-25º
Tomorrows Wind Speeds (mph): 5-15 mph
Tomorrows Wind Directions: W
Tomorrows Sky Cover: Mostly Clear
Tomorrows Snow (in):0″
Name: Brian Goldstein
Title: Snodgrass Avalanche
Location: Crested Butte Area
Date of Observation: 11/25/2014
Aspect: North East
Elevation: 11,000
Avalanches: Observed an Avalanche on the Northface of Snodgrass in between first bowl and second above the open pillow zone. Propagated 120 feet wide and was much bigger than the anticipated potential. Probably an R3D2.5. Ran approx. 500 feet into the terrain trap below snapping numerous small trees. Almost propagated an additional 40 feet, but stopped with a major crack on a knob above an adjacent gully. We were observing the terrain from sheltered trees about 5 feet from an open area on the ridge above the rock formations/pillows. Aspect was NorthEast. We stomped around above some convexities with no reaction. Deciding the terrain was unsafe we turned around, walked five feet into the trees and the slope was remotely triggered presumably from a small buried tree. Slid all the way to the ground. The storm slab, and slab from last week, slid on the weak faceted layer at the base of the snowpack, taking the entire snowpack with it. One other wumph was observed in the same area prior to the slide. The crown was approx 60 cm. Consistent crown with no obvious wind deposits, although this specific area is subject to wind loading due to its exposure and openness compared to the rest of the snodgrass trees. Slope angle averaged about 38 degrees as the starting zone.
Weather: Light to moderate winds. Moderate temps (21ish?). Snowing S1.
Snowpack: 60-100 cm
Remotely Triggered Avalanche on 11.25.2014
Catagorized : (SS-R2-D2-AS-O/G)
Name: EM
Title: Ob from 11/24
Location: Kebler Pass Area
Date of Observation: 11/25/2014
Aspect: South
Elevation: 11,500
Weather: Weather – Cloudy skies with light snow falling. Air temps were 17 at trailhead and 8 at 11,500. Winds were light with moderate gusting. Observed a small bit of snow being transported by wind, but low visibility didn’t allow for good views in to the alpine. Ski tracks from Sunday were partially filled in at and near treeline.
Snowpack: Snowpack – while traveling off of skin track at treeline small amount of cracking with in the new snow was visible. Jumped on several steep roll overs with out any results. No collapsing either. Snow profile was dug at 11,500 on open, south facing, 32 degree slope. It showed 65cm snow depth. It was comprised of 30cm of 1-1.5mm facets at ground from earlier in november, a 5cm crust the formed from last weeks sunny skies, and then 30cm of new snow since saturday on top. Test results showed reasonable bonding between new snow and sun crust, no results from jumping on steep rolls or shovel shears. CT showed failures below the sun crust on taps from elbow. These were generally Q2. ECT results would not propagate across entire column only about 30cm and were irregular. It appeared as though there may have been a strong temp gradient directly below the sun crust leading to a weakening of the snow directly below it. But battery in thermometer died so no data.
Date of Observation: November 24, 2014
Location: Kebler Pass Area
Aspect (N/S/E/W, etc.): N-NE
Elevation: 9800-11400
Returned to the same zone as yesterday, see WD’s report from 11/23. An additional three inches or so and evidence of strong wind activity overnight. Observed some whoomphing and cracking at the top of the skin track on the ridge where there was lots of wind deposition. Pit at the top of the line we skied confirmed the additional three inches up high. Storm snow was still unconsolidated but ran easily on the old surface, we expected to see loose snow sluffing. Entire pack failed on the ground facets with considerable force. No signs of instability on decent of that line. On the second run wrapping around toward exit trees we observed lots of wind loading and a very defined wind slab of 6 inches or so which failed easily on rollovers.
Forecaster and user submitted snow and avalanche photos from across the Crested Butte Avalanche Center’s forecast area in Elk Mountains of Central Colorado.
Release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. The are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
Predicting the release of Glide Avalanches is very challenging. Because Glide Avalanches only occur on very specific slopes, safe travel relies on identifying and avoiding those slopes. Glide cracks are a significant indicator, as are recent Glide Avalanches.
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind lips of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Cornices can never be trusted and avoiding them is necessary for safe backcountry travel. Stay well back from ridge line areas with cornices. They often overhang the ridge edge can be triggered remotely. Avoid areas underneath cornices. Even small Cornice Fall can trigger a larger avalanche and large Cornice Fall can easily crush a human. Periods of significant temperature warm-up are times to be particularly aware.
