snow surveys

CB Avalanche Center2014-15 Observations

LOCATION: Crested Butte Area
DATE OF OBSERVATION: 02/24/2015
NAME: ADB
SUBJECT: snow surveys
ASPECT:
ELEVATION:

 

AVALANCHES: Numerous slides observed on Axtell and Happy Chutes. Most of the slides were soft slab. Damage scale was mostly D1 with some D2. Aspects where activity occurred was from NE to E.

WEATHER: Mostly sunny. calm. Hot

SNOWPACK: Snow survey depths for Red lady Glades: 25 to 35.5 inches for 5 measurements.
Snow Survey depth for Butte: 25 to 42.5 inches for 12 measurements

UPLOADS:

Gothic snow and avalanche obs

CBAC2014-15 Observations

Only 1″ new snow with very light snow Monday morning and after dark, then clear and cooler than it has been (-03ºF).  Snowpack settled from 48″ to 45½” now.

There were a number of point releases off steep slopes but also 4 one  foot fractures on Snodgrass starting at various elevations, all small but a couple running about 400 feet or so.

Recent Natural Avalanches along Kebler Pass Road

CB Avalanche Center2014-15 Observations

LOCATION: Kebler Pass Area
DATE OF OBSERVATION: 02/24/2015
NAME: Zach Guy
SUBJECT: Recent Natural Avalanches along Kebler Pass Road
ASPECT: North, North East, East, South
ELEVATION:

 

AVALANCHES: Good view of recent avalanche cycle from the weekend’s storm. About a dozen soft slabs, D1 to D1.5’s, failing at the storm interface on northwest to east-northeast aspects. (Several on Mt. Axtell, Carbon Peak, East bowl in the Anthracites, Northwest bowl in the Anthracites, above Coal Creek, and in the Anthracite Range). Most of these were near/below treeline, and two were above treeline near Ohio Peak. Two notable slides had larger crowns, and looked to have failed on older, deeper layers, several feet deep and D2 in size. One was a heavily crossloaded slope on Mt Axtell, NE aspect below treeline. The other was a north facing bowl below Ohio Peak. I think the latter failed today. There were dozens of dry loose avalanches, D1 in size, on various aspects, and a number of natural wet loose avalanches ran today on southerly aspects, but didn’t see any slab avalanches on these aspects in the Ruby Range or Peeler Basin.

WEATHER: Clear skies. Calm winds. High of 32 at 10k.

SNOWPACK: Snow surfaces became moist on E through S through W aspects today.

UPLOADS:

Red Coon Glade

CBAC2014-15 Observations, Avi Blog

NAME: Evan Ross
DATE: 2/23/15
LOCATION: Red Coon Glade
ELEVATION: 9,000-11,700ft
ASPECT: SE

WEATHER: Overcast sky was breaking up in the afternoon. A frew s-1 snow showers through out the day. Strong solar through thin clouds was creating a green housing effect. Calm wind throughout the day.SNOWPACK/AVALANCHE OBS: Green housing and some solar warmed the snow surface and created a 1-2cm crust by the afternoon. Had pits along the way found generally good bonding between the new/old snow interface as well as the new snow lacking a cohesive slab. HST at 11,000ft was 40-45cm. BTL south facing slopes grater then 30 degrees and below 10,000ft where bare of snow before this storm.

Ski cuts on a small shaded slope BTL that was about 35 degrees produced small storm slab avalanches on the old snow surface about 15 feet wide.
Observed several loose snow avalanches on a steep easterly slope near treeline that looked to set down into the facets below. These D1.5 sloughs may have failed naturally or where skier triggered from the ridge above.

Natural and skier triggered avalanches in Slate River Basin

CB Avalanche Center2014-15 Observations

LOCATION: Crested Butte Area
DATE OF OBSERVATION: 02/23/2015
NAME: Zach Guy
SUBJECT: Natural and skier triggered avalanches in Slate River Basin
ASPECT: North, North East, East, South
ELEVATION: 9,000 -11,400 ft.

 

AVALANCHES: Observed ~10 natural soft slab avalanches failing on the storm interface (near surface facets) mostly below treeline and a few near treeline slopes on North and Northeast aspects. Slabs were generally 40 to 150 feet wide, 12″-16″ deep, and ran a couple hundred vertical, not large enough to bury someone. Observed slides in Schuykill Ridge, Climax Chutes, Happy Chutes, and Peeler Basin. (SS-N-R1-D1-I). One exception was a wider and longer running slide on Schuykill Ridge, maybe 300-400 feet wide and ran 1,000 vertical, D2 in size.

We skier triggered about 15 similar slides, all BTL on N/NE aspects on Schuykill Ridge. D1 in size on relatively small terrain features. Slides behaved like storm slabs in that they didn’t propagate beyond the steep rollovers and wouldn’t trigger remotely.

WEATHER: Overcast to broken skies. Calm winds. Very light snowfall (S-1) tapered by 10:00 a.m. Mild temperatures.

SNOWPACK: 12″ to 16″ of fist hard storm snow, zero wind affect. Formed a soft slab over widespread near surface facets on N/NE, thin crust over facets on E, and thick crust on S. Storm snow was very reactive anywhere that it was on near surface facets. Widespread shooting cracks up to 100 feet, some collapsing, and anything over 36 or 37 degrees was almost a sure bet it would slide. No signs of instability on south aspects and got one collapse on an east aspect, under the thin crust. Below the storm slab, the snowpack was faceted throughout, and didn’t feel persistent slab structure, even near ridgetop. However, we didn’t poke around under the large, windloaded start zones that are likely to be holding stronger mid or upper pack.

UPLOADS:

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Schuykill Ridge. NE aspect  SS-N-R1-D1-I

 

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Schuykill Ridge, NE aspect.  SS-N-R2-D2-I

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Skier triggered soft slab.  Schuykill Ridge. N or NE aspect BTL

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Skier triggered soft slab.  Schuykill Ridge. N or NE aspect BTL

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Skier triggered soft slab.  Schuykill Ridge. N or NE aspect BTL

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Skier triggered soft slab.  Schuykill Ridge. N or NE aspect BTL

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Natural soft slabs on Peeler Peak.  SS-N-R1-D1-I

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Skier triggered soft slab.  Schuykill Ridge.  NE aspect BTL

Snodgrass

CBAC2014-15 Observations

NAME: Jeff, Donny

DATE: 20150222

ACTIVITY: Avy L2

LOCATION: Snodgrass
ELEV: 10,000
ASPECT: E/NE
WEATHER:  OVC, S1, Calm throughout the day, + < 0.5MM
AVALANCHE / SNOWPACK OBS:
No signs of instability until 13:30 w/ ~4.5″
@ 13:00
SS-ASi- R1-D1-O  NE @ 9,700 slope Angle ~37*  very small moved only a couple feet before losing momentum
@ 14:00
SS-ASi-R1-D1-O  NE @ 10,600 slope angle 40*  slow moving slough in forest @ ridgetop, no prop, stepping down into older facets 6-10″
SS-ASu-R1-D1-O    NE @ 10,200  slope angle 36*  30x45ft ran very slowly, 4.5″ of stormslab bonded to old snow, failing in old facets 6-10″ down & then gouging down entraining more facets like a slough
SS-ASi-R1-D1-O  @ 37* bordering alongside  same dimensions
SS-ASi-R1-D1-O     @ 37* (immediately next to previous) but running as a fan shaped loose dry.
Snowpack: large collapse with only 1 skier, immediately before these three small skier triggered on flats 80 feet away.  facets collpasing under a 2cm crust with storm slab stuck to crust.  Slight drop in elevation from ridge resulted in noticeably denser snow.  HS 100cm
on the 21st we obsereved a similiar collapse @ 10,000ft  (HS 100cm on 5 degree W slope) but with a group of 7 close together.  no cracks so weak layer could have been the facets failing under the 2cm breakable crust.  Or the still intact SH layer we found ~20cm down.
Bonding tests:
@ 13:00 @ 10,200 ECTP2  SC  (15cm down in facets covered by 2cm crust & storm snow)
No signs of surface hoar layer being reactive in 3 different pit sites (8 seperate pits) in Snodgrass saddle zone between 10,200 -10,500ft.  Only faint traces of it remaining in 1 pit, otherwise unseen.
Dec 13 layer very visible to the eye & producing CTM to CTN results but no propagation.

Gothic Morning Update

CBAC2014-15 Observations

Date: 2/23/15

Light snow during the day Sunday but steady moderate snow overnight, becoming light near sunrise.  The 24 hour totals are 13″ new with 0.87″ water and now at the winters deepest snowpack of 48″. Thankfully no wind.  Currently overcast and calm with very light snow and mild- between 16 and 18ºF overnight. billy bar

Coneys, Washington gulch

CBAC2014-15 Observations

GUIDE(S): Alex &Evan
DATE: 2015-02-22
LOCATION: Coneys, Washington gulch
ELEVATION:9,400′-10,900′
ASPECT: N-NE
WEATHER: Overcast, snowing S1 throughout the day with periods of s2-3 around 1600. No snow transport at ridge top, calm winds, G10 tops. Temps in the mid 20s.  
 
SNOWPACK/AVALANCHE OBS: No signs of instabilities throughout coneys bowl. 6″ new snow made for soft turns over supportable crust skiing. The new snow seemed to be bonding well to old snow surface, no new slab formation with no results via hand pits. All aspects with an easterly tilt had a noticeable crust below new snow. 

 

Purple Palace

CB Avalanche Center2014-15 Observations

LOCATION: Paradise Divide Area
DATE OF OBSERVATION: 02/22/2015
NAME: Zach Guy
SUBJECT: Purple Palace
ASPECT: North, North East, East, South East
ELEVATION: N/ATL

AVALANCHES: None, except minor sluffing.

WEATHER: Steady S1 through the day, increased to S2 around 4:00. Calm winds. Overcast. Mild Temps

SNOWPACK: By 4pm, 8″ of storm snow at ridgeline and 4″ of snow at valley bottom; no wind affect. About 2-3″ of new through the day. New snow was too shallow and incohesive for slab formation; no storm slab concerns (yet). Falling on near surface facets on North/Northeast aspects. On these slopes, the snowpack felt almost entirely faceted in many places, except as we got higher near treeline, where some lingering stronger midpack prevailed. 5 pits, never saw surface hoar, but fist hard facets in every pit in the upper snowpack. The only pit with propagating results was a windloaded feature where a shallow, persistent slab from recent wind events was over near surface facets. On East and Southeast aspects, the new snow is on meltfreeze crusts. Warm snow seemed to be bonding decently, but there were a few slopes with thin crust /facet/crust sandwich (Feb 20th and Feb 16th crusts), and these produced small, localized cracking. Bottom line – plenty of weak layers out there under this storm snow, just need more snow/wind loading.