Irwin 12/3/14

Name: Zach Guy
Title: Irwin 12/3/14
Location: Kebler Pass Area
Date of Observation: 12/03/2014
Aspect: West
Elevation: Near treeline

Avalanches: 8 airblasts, 2 handshots on several previously untouched West facing paths N/ATL produced no significant results. One soft slab 5” deep, 20 ft wide, running on the Nov 22 facet layer in OL. SS-AB-R1-D1-O

Weather: Brief periods of S-1. Trace accumulation.

Snowpack: On west facing aspects near treeline: Snowdepths 70-120 cm deep. Mostly faceting midpack across slopes, some isolated slabbier feeling areas particularly behind tree fences. Nov 22 facet layer is 6-12” deep, appeared to be more preserved behind shading trees. Varying CT results, No ECT results on this layer. Nov 2 depth hoar layer is moist, rounding. No results on this layer. Several layers of melt-freeze crust and rime crust near the surface, with some rounding facets in between.

Tracking the Persistent Slab Problem in Paradise Divide

Name: Zach Guy
Location: Paradise Divide Area
Date of Observation: 11/30/2014
Aspect: North, North East
Elevation: 9,500 ft – 12,400 ft

Avalanches: No recent slides. The crown investigated was a NE aspect at 12,300 ft on Mt. Richmond. HS-N-R2-D1.5-O that likely failed about 5-6 days ago. The slab was 50-100 cm deep, 1F hardness. It failed on a thin layer of ~1mm rounding facets (Nov 12 interface) over a 2 cm meltfreeze crust (late October layer), which caps a thicker layer of 2-2.5 mm faceted crystals (October layers). Stability test above the crown was ECTN 25 Q3 on the Nov 12 facet layer

Weather: High, thin overcast, warm temps, and moderate NW winds

Snowpack: Below treeline: Snowpack is entirely faceted; no concerning structures. Still supportive on skis but trending towards trap-door. Surface is fist-hard near surface facets.

Near and Above treeline: Snowpack is quite variable. Most areas (~70% of terrain) hold a shallow snowpack (<80 cm) due to wind erosion. The snowpack there is faceting from the top down, with easy pole plants to the ground and lacking a concerning structure.  Specific windloaded features, such as gullies and below convexities, are still harboring slabs up to 130cm thick and 1F in hardness. Several targeted stability tests in these suspect areas showed poor propagation potential on the basal weak layers (ECTN, ECTX on October and early November facets, 4F to 4F+, .5 mm up to2.5 mm in size). One of these pits was dug at the crown of a persistent slab avalanche that failed an estimated 5-6 days ago. The Nov 22 interface was consistently indistinct and produced no results in stability tests. We jumped around on numerous small test slopes and traveled on steep terrain with no signs of instability. The surface is mostly soft, wind-rippled near surface facets with pockets of firm windboard.

I quickly poked onto a steep South aspect at 12,300 feet. The surface is a supportive melt-freeze crust roughly 2″ thick.

20141130 Richmond Crown

Crown profile from older slide on Mt. Richmond. NE Aspect ATL

11/30/2014

Location: Paradise Divide Area
Date of Observation: 11/30/2014
Aspect: North East
Elevation: 12,000

Avalanches: No recents signs of instabilty .

Weather: Partly cloudy with winds from the SW gusts from 10-15 mph

Snowpack: Windloading on NE slopes above treeline .

Irwin Obs 11/29

Name: Irwin Guides
Title: Irwin Obs
Location: Kebler Pass Area
Date of Observation: 11/29/2014
Aspect: East, West
Elevation: Near and above treeline

Snowpack: Overall tracking two interfaces: Nov 12th & Nov 22nd . The November 22nd is the more suspect and made up of a thin sun crust that seems to be becoming less distinct depending on aspect and elevation. The November 12th is on the Ground in many areas but on a facet layer anywhere the Nov 3rd storm did not melt away.

East: Skied and dug test profile on Binge (ESE 11,800’). No signs of instability, HS 60-80cm. Very thin crust on surface. Nov. 22nd interface very indistinct. Uniform snowpack. Ski pen 15cm.

West: Thortons (WSW 11,300’) No signs of instability. HS: 30-80cm and variable surface from crusts on SW to DF and soft on West. Crust was almost supportive in places. November 22nd crust was not continuous though still produced some results. Ski pen 10-20 cm.

Snowpack Ob 11/29

Name: Venn
Title: Snowpack Ob 11/29
Location: Paradise Divide Area
Date of Observation: 11/29/2014
Aspect: North East
Elevation: 11,000

Weather: clear sky giving way to clouds after 3pm. moderate winds on valley floor and on ridge around treeline. however skin track was filled in from blowing snow possibly from day before. winds looked to be stronger up higher as we saw snow blowing over some of the peaks above 12,000 ft.

Snowpack: snow on sunny aspects became very wet and dense early on around 11pm. shady aspects on NE slopes have stiffen. ski penetration approximately 12 inches. noticed some wind slaps forming off of ridge on NE aspects. no signs of instabilities.

11/29 Snowpack Observation

Name: Evan Ross
Title: 11/29/14
Location: Paradise Divide Area
Date of Observation: 11/29/2014
Aspect: North East, South East, South
Elevation: 9,800-11,300

Weather: Mostly clear with a period of overcast sky in the afternoon. Gusty down valley winds that would come and go. Above freezing temps near 40f through the day.

Snowpack: Toured in the near treeline elevation ban on a few south, southeast and northeast slopes. No obvious signs to instability on any slope. Checked in with the 11/22 interface on all slopes and could only get a result on SE. CTM RP on what looked like small NSF and an ECTX. The only slope that wasn’t moist, of the selection, was NE.

Natural Persistent Slab

Name: Evan Ross
Title: Natural Persistent Slab
Location: Paradise Divide Area
Date of Observation: 11/28/2014
Aspect: South East
Elevation: 9,800-11,800

Weather: Mostly clear sky, calm winds with a few gusts at ridgeline and air temperature near or above 40 degrees.

Snowpack: Many slopes from south east to south to west had a moist snow surface at all elevations traveled.. The snow surface has seen lots of settlement over the last few days and become much more dense. Even on a north facing slope at 10,500ft with dense trees where ski penetration was around 10-20cm.

No instabilities were observed on a 36 degree south slope while traveling and skiing around 11,000ft. See attached snowpit profile below.

Avalanches: Observed 2 natural persistent slabs that failed on the 11/22 interface, around noon on south eastern slopes with crown elevations at 11,800ft.

SS-N-R2-D2-O. Crown width about 300ft wide averaging 12 inches deep. See attached profile and pictures below.

SS-N-R1-D2-O. Crown width about 80ft wide averaging 12 inches deep.

Pit dug on a similar slope and elevation to a natural avalanche on 11/28/14. SS-N-R2-D2-O. (Click title to see Profile)

The weak layer. 2mm facets on a 1cm crust.

Natural persistent slab avalanche that failed on the 11/22 interface, around noon on a south eastern slope with crown elevation at 11,800ft. Crown width about 300ft wide averaging 12 inches deep. SS-N-R2-D2-O.

11/26/2014

Name: Evan Ross
Location: Paradise divide area
Date of Observation: 11/26/2014
Aspect: North East
Elevation: 10,000-11,500

Weather: Clearing sky, generally warmer temps then pervious days, west northwest winds gusting strong enough to continue drifting snow at near and above treeline elevations.

Snowpack: Last weekends storm snow was wind buffed and consolidated into a more cohesive slab.  This slab was still fist hard but noticeably more consolidated then previous days. This didn’t seem to affect the outcome of stability tests in the same areas as tests from previous days on the same slopes. Collapsing has decreased from previous days as well, but ECT test still show the potential for avalanching of the persistent slab and week fasted snow on the ground.

Avalanches: 1 natural wind slab within the 48 hours failing on an above treeline cross loaded Southern slope. SS-N-R2-D2

Irwin Snow Obs

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

2014/11/25

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.