Upper East River Basin/Gothic

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/28/2017
Name: Steve Banks/Mike Soucy
Subject: Upper East River Basin/Gothic
Aspect: North East, East, South East, South, South West
Elevation: 9000-11100

Avalanches: About 10″ of new snow since yesterday morning. Lots of small, localized collapses underfoot throughout the day on all aspects travelled on. 1 test profile showed HS 230 cm with 35 cms of newer snow over crust facet sandwich. ECTX but prying with the shovel popped the slab off on 1cm thick .5 mm facets between 2 crusts.
Remote triggered a D2 and a small D1 on the NE slopes of Snodgrass skiers left of the low point of the saddle. Triggered from a small bench about 200′ away from the slope. 200′ wide running about 600 vertical with a crown of up to 53 cms. Weak layer was buried near surface facets. 35 degree slope at 10,400′ Crown investigation showed CT 21 SP failing on the same NSF.
Also noted a large D2.5 off of the East face of Gothic initiating just below the very large cornice on the summit ridge and running to about 10,200 just above the valley floor.
Watched a release out of very steep terrain, East facing above Copper Creek likely windslab and maybe D2. Noticed 2 other pockets, mid elevation roughly 10,600 with minimal propagation and D 1.5.
Peak of instability seemed to come around 3 pm today. Surface snow became noticeably stiffer in the afternoon.
Weather: S-1 most of the day with periods of S3. Increasing winds through the day as snow decreases with strong gusts in the afternoon. Winds from the West and high temp of -7.
Snowpack:

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Irwin Tenure

CB Avalanche Center2016-17 Observations

Location: Kebler Pass Area
Date of Observation: 02/28/2017
Name: Irwin Guides
Subject: Irwin Tenure
Aspect: East, South, West
Elevation: 10,000-12,000

Avalanches: numerous cracking and shallow windslabs. one natural overnight in Sonic from heavy wind loading, D1, 12″ deep, 30′ wide. Explosive work did not produce significant results, despite large shots (5-12£)
Weather: Heavy snow at times during morning, gradually tapering after lunch, but still moderate snow showers. West winds 20 G60, especially in afternoon, cold temperatures with highs at ridge barely reaching 10Âo and temps at 10k topping out at 19Âo.
Snowpack: Storm total as of 1500 sits at 18″ with 1.5″ SWE. 9% density overnight, with slightly lighter snow today, created widespread slow stuffing in terrain steeper than 33Âo, shallow windslabs developing with ideal westerly winds blowing 20 G 50. New snow is variable across terrain due to wind, some places scoured to crust, others 3ft deep. BTL, snow is uniform and deep, with ski pen 30-40cm.

photo on drive down Kebler of North facing Coal Creek.  Suspected surface hoar near creek bottom.  notice no fracture very close to trees, no surface hoar development there due to constant longwave radiation.

5am Gothic Townsite Snow Obs

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/28/2017
Name: billy barr
Subject: 5am Gothic Townsite Snow Obs
Aspect:
Elevation: 9300

Avalanches:
Weather: Strong, steady wind until nearly 3 a.m. with driven, dense snow. Wind becomes light as snow picks up though still dense with 4½” new by 5:30 a.m. and water of 0.53″ (water is from instrumentation not official but probably very close). Snowpack back to 89½”, just 1½” below winters deepest. A nasty night, nasty morning and nasty winter (these views are those of the Gothic weather station and in no way reflect those of the greater CB area- even if they are correct).

Currently moderate snow and light, steady SW wind with obscured cloud cover. Temp. overnight ranging only from 22 to the current 19ºF. billy
Snowpack:

Mountain Weather 2/28/2017

CB Avalanche CenterWeather

Date: 02/28/2017

Snow will continue through much of the day, before tapering off toward sunset. Moderate to strong west winds will continue most the day, before lessening tonight as the jet stream over head moves eastward. Temperatures and windchills will remain bitter, with highs at 11,000ft only reaching the upper teens. Today’s storm will clear out for generally sunny skies the rest of the week, and light northwesterly winds by Wednesday morning and beyond.

Windy Schuylkill Ridge

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/27/2017
Name: Travis Colbert
Subject: Windy Schuylkill Ridge
Aspect: North East
Elevation: 11,400

Avalanches: Remotely triggered a cornice break skier’s left side of Yogi’s that triggered a small soft slab avalanche 12+ inches deep. Skier triggered a few small pockets on isolated convexities. Some sloughing, that toward the end of the day was exhibiting almost soft slab-like movement.
Weather: Strong SW wind (30+ mph) and snowing.
Snowpack: 12+ inches of soft, non-cohesive snow becoming noticeably more cohesive over the course of the day. Skied Snakey, Thanksgiving Bowl and Birthday Bowl. Massive cornices along the entire ridge due to several days of strong W & SW winds. Amazing skiing with particular caution at the wind-loaded entrances. Snowfall and winds were increasing as the day progressed, and I expect these slopes to be touchy in the days ahead.

Pittsburgh slab

CB Avalanche Center2016-17 Observations

Location: Paradise Divide Area
Date of Observation: 02/27/2017
Name: Evan Ross
Subject:
Aspect: North East
Elevation: 9,200-10,400

Avalanches: Investigated the crown profile of a human triggered avalanche on 2/26. Test results below. Bed surface averaged 37 degrees and crown averaged 14 inches thick breaking into old snow layers. Debris looked to be D1.5 in size. Could have been larger if the terrain was bigger.

After an additional 4″ of new snow, a ski cut on the skiers left flank propagated another soft slab an additional 240ft wide across the rest of the 37 to 40 degree slope.
Weather: Overcast sky in CB became obscured by S-1 snowfall heading out to Pittsburgh at 10am. snowfall picked up to S2 just after noon and continued as we headed home about 2pm. Light and variable winds below treeline with some stronger gusts.
Snowpack: 10 to 14″ of snow has accumulated during the last week over two different NSF interfaces. 2″ were added last night with another 2″ added by 2pm. These NSF layers are each capped by slightly firmer NSF grains (half step hand hardness). Probably from a temporary period of warming before getting buried. The NSF grains are .5 to 1mm in size and 3 to 6cm’s thick, with weak fist hardness.

Basically no obvious signs to instability while up tracking on slopes up to 37 degrees in steepness, with the current slab being so soft. Hand pits produced sheers at the upper NSF interface. Crown profile had an ECTP 15 SC on the upper NSF and an ECTPN on the lower NSF interface which was the weak layer in this human triggered avalanche.

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Natural slabs ATL

CB Avalanche Center2016-17 Observations

Location: Kebler Pass Area
Date of Observation: 02/27/2017
Name: Irwin Guides
Subject: Natural slabs ATL
Aspect: South East, South, South West
Elevation:

Avalanches: D2 South Owen, D1.5 West Col between Ruby and Owen, D2 NE Owen, D2 E Scarps

D2 Bender: SS-R1-D2-AB-I 38* Wind loaded crown 30cm -70cm deep, flank ~20cms. HST sitting on MFcr (K) very thick. Under the cliffs, stepped down again to crust , cleaning out AM Snow Safety tracks.
Weather: CLR, 0 degrees at Ridgetop 1200. Clouds building in the pm. Increasing winds transporting snow throughout the day. COLD!
Snowpack: The Crust/Facet/Crust combo is much closer on Southerly slopes, crusts separated by 1-2 cms. Further West the separation between crust layers increases to +15cms. Crusts on Western terrain are buried up to 40cms deep. Two collapses in the flats below Swill/Bender. No Cracking East or West. Barker marker basin pit on collapse site: SC 44cm down of FC (very thin layer of F-hard 1mm) just above lower MFcr. Layer above is 4F FC then the top MFcr. The storm snow slab is ~35cm deep of 4f to F on surface.

Natural D2 on South Face Owen

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Explosive triggered D2 Bender: SS-R1-D2-AB-I 38*

Bender

Mountain Weather 2/27/2017

CB Avalanche CenterWeather

Date: 02/27/2017

The cold part of winter has come back, now lets add the snow. Snow showers will slowly increase in intensity this afternoon before peeking Monday night. An upper-level trough of low pressure is dropping southeast to Colorado as a cold front also moves in north of us tonight. The jet stream will further add instability aloft while subtropical moisture increase from the southwest. This combination will add up to a blustery winter storm starting late this afternoon. Snowfall continues through Tuesday, before the flow aloft turns northwest on Wednesday and begins to dry out. We could look at a blanket statement 12-22” of snow out of this storm. Strong winds will also be drifting and redistributing this new snow.

Small soft slab

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/27/2017
Name: Evan Ross
Subject:
Aspect: South East
Elevation: 9,200-11,400

Avalanches:
Weather: Mostly clear sky became partly cloudy in the afternoon. We were mostly protected from winds, but they certainly picked up int the afternoon with plums off the high peaks and swirling snow in the glades above 10,500.
Snowpack: Didn’t travel in avalanche terrain. About 15cm’s of new snow from the last week. At 10,800ft on a south facing 30 degree slope the crust below the most recent snows was stout. On lower angled slopes at 11,200ft the crust facet sandwich was there, but not as concerning looking as seen in other places.

Kicked a cornice off low on coon ridge. It slid down to below the windload and released a small 20ft wide soft slab, 25cms deep, probably on the buried near surface facets. The weakness is there, just needs more of a slab to propagate.

Pittsburg

CB Avalanche Center2016-17 Observations

Location: Paradise Divide Area
Date of Observation: 02/26/2017
Subject: Pittsburg
Aspect: East
Elevation: Below Tree Line

Avalanches: Unintentional skier triggered 8-10″ soft slab on crust (storm snow/wind affected?) breaking on 30+ degree rollover below treeline. Propagated ~60 feet across and slowly ran down slope behind skier ~300′ before stopping on bench. East/Northeast facing slope to skiers right of Pittsburg proper.
Weather: Cold, sunny most of day with light clouds moving in midafternoon, light wind with stronger gusts visible transporting snow above treeline, no precipitation.
Snowpack: Boottop creamy snow skied great.

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