Location: Paradise Divide Area
Date of Observation: 12/20/2018
Name: Eric Murrow

Subject: P-Divide sunny alpine
Aspect: South East, South, South West, West
Elevation: 10,800 – 12,450

Avalanches:

One fresh looking avalanche (crown still pretty sharp) on a westerly terrain feature that gets loaded from northerly winds. D1 in size

Weather: Lots of sun with thin high clouds filtering the sunlight. Light winds through late morning and early afternoon; as we left the area around 1pm winds began to blast snow around in the alpine- did not look like much loading just a blustery mess.

Snowpack: On ascent, we crossed a westerly slope near treeline that I had crossed about a week ago and found that it had weakened during this period and didn’t seem to have as much strength – ski pen was deeper than a week earlier. Surface on this west slope was still dry without a sun crust present.

Much of the alpine terrain visible from up high looked scoured and beat up from the previous days wind event.  I bet there were a few small, fresh, thin windslabs out there tucked behind terrain features like the one pictured below. Skied a south facing slope that had 2-4 inches of new snow resting on a semi-supportive crust. Skied through the drifty looking SE facing feature in the area and did not find a windslab. Looks like the wind blew the snow further downslope or into the basin below. At around 11,200 in the basin found a small isolated strip of deposited snow up to about 10″ thick-not avalanche terrain but made for about 10 quality turns.

Photos:

Location: Paradise Divide Area
Date of Observation: 12/20/2018
Name: Evan Ross

Subject: Afternoon Lap. Skook
Aspect: North East
Elevation: 9,000-11,300

Avalanches:
Weather: Clear other than some high thin clouds. Calm wind.
Snowpack: Getting pretty simple out there. Couldn’t find a persistent slab to worry about, and didn’t encounter a wind slab to worry about either in the one line skied. Feeling around on the BTL to NTL skin up, HS increased from about 60cm to 90cm on average. Those numbers are low because just about everything out there in our area had previously avalanched a couple weeks ago. The snowpack is fast and fun on skis, with ski pen around an estimated 20cm. While boot pen is sinking right through most of the pack. Even the trees had wide propagating avalanches from earlier in the winter. The 12/19 interface will be the new layer of concern as we build back the slabs. The NSF at the 12/19 interface is much more pronounced and weaker below 11,100ft, while increasing in elevation above that, the grains start decreasing in size and are not quite as weak. About 2-3″ of new snow on the 12/19 interface overall.

Poked a hole on the edge of some wind-loaded terrain with a great fetch for westerly winds. Wind-loading had come from the west, but also down the ridge from the northwest. Maybe not the best orientation for the biggest wind slabs to develop out or the last 24 hours. Never the less the windslab was only around 4-5″ thick here and tilt test had it fail within the new snow and just above the NSF. This was a P hard slab in the upper 2 inches and 4f below that. HS here was 130cm as it was above the crown from the natural avalanche activity a couple weeks ago. Probing hear had a more pronounced strong over week structure but its total area was very small.

Photos:

Location: Kebler Pass Area
Date of Observation: 12/19/2018
Name: Tyler

Subject: Red Lady Glades
Aspect: South East, South, South West
Elevation: 11,600

Avalanches:

No observed avalanches or signs of instability

Weather: Periods of intense snowfall and windy flurries. Windy in the open and on the ridge, relatively still in the trees. Lots of blowing snow where there was heavy wind. Wind out of the West
Snowpack: Stayed on low angle terrain all day and saw lots of different snowpack make-up. Where areas were highly wind effected and wind scoured there was hardly any new snow where protected areas had large deposits (during one low speed turn I felt new snow reach up to just below my knee while riding above the crust below the new snow). A crust was present beneath the new snow accumulations on most aspects at all elevations. The crust varied in its thickness and strength.

Photos:

Location: Kebler Pass Area
Date of Observation: 12/19/2018
Name: Tom S

Subject: Anthracite Range
Aspect: North, North East, South
Elevation: 10300′ – 11,7500′

Avalanches:

N/O

Weather: The weather Fx was pretty much spot on 4″ of new snow in the Anthracite range. The majority of the snow came early than forecasted with heavier precip. rates between 8 and 10 AM then tappering throughout the rest of the day. The winds were exactly as forecasted steady from the N in the 20mph range and gusting to 40 at noon. Temperatures remained in the teens to twenties throughout the day.
Snowpack: “Little bit of blowing snow.” Windward slopes becoming wind scoured with strong gusts disrupting the surface hoar. Old tracks still visible on all aspects observed there was some small wind slab development on NE aspects but isolated to areas NTL. Not too much wind loading observed on S aspects 3-4 inches of new on top of a 1″ crust. Saw no signs of instability through the day. Dug one PIT N aspect 10,400′ ETCX burping the burping the baby to see the reactivity of the newly buried surface hoar (profile attached). This will be a layer to pay attention to in the future after our last period of high pressure.

Photos:

Location: Kebler Pass Area
Date of Observation: 12/18/2018
Name: Steve Banks & Zach Kinler

Subject: SE-S-SW-W NTL
Aspect: South East, South, South West, West
Elevation: 12,000

Avalanches:

No new avalanches observed, though several shallow soft wind slabs were noted, presumably from the little storm late last week.

Weather: Warm temps around -5 C all day. A thick cloud band passed by late morning, then mostly sunny until 3 pm when clouds built in again. Calm winds increased in the afternoon with gusts into the 20’s and a little moving snow.
Snowpack: We went looking for Persistent Slab structure today and had a harder time finding it on Southerly slopes. Where we did find it it was unreactive to our snowpack tests. Southeast and South facing slopes had a noticeable lack of weak snow at the ground, while Southwest to West slopes still showed this PS structure to some degree. Overall HS ranged from 110 to 70 cms with areas above treeline being in the 20 to 60 cm range.
Non of our snowpack tests produced a result.
Surface conditions are a mixed bag and will be interesting in the future. South slopes had multiple sunbursts in places, while SW had a crust on top and a softer crust just below. All these crusts had small facets above and below. 2mm Surface hoar and 1mm Surface Facets were noted on all aspects and elevations traveled, though the sun and light winds were taking a toll on them.

Photos:

• Indy-Basin-20181218.pdf

• Elk-Basin-2018-12-18.pdf

• Asia-Profile-2018-12-18.pdf

Location: Paradise Divide Area
Date of Observation: 12/18/2018
Name: Evan Ross

Subject: Crusty and Dusty? Crunchy Bread and Soggy Bread? Good and Bad? Hard and Soft?
Aspect:
Elevation: 10,800-12,800

Avalanches:
Weather: Partly cloudy early in the morning, then overcast through noon and bluebird in the afternoon. Light winds at ridgeline with some moderate gusts.
Snowpack: Little bit of everything out there. Don’t need to talk about the crusty south, so how about the snow on east and north. No signs to instability today, but still traveling with the threat of Persistent Slab structure in mind. Spend a good bit of time skiing around on an above treeline northeast to east to southeast facing bowl. The Northeast portion of the bowl was mostly all old avalanche debris with about 20cm of NSF on top of those debris. Felt like skinning in a sandbox. Moving across to east the snow surfaces were not as bad in regards to persistent gains, but still some small faceted grains on the surface. Crusts formed as the slope started having southerly tilt and I didn’t spend time looking at those crusts. HS 100-130 at 12,000ft in this area.

Traveled through a good hunk of BTL north. These were steep upper 30 to 40 degree slopes and just about everything had previously avalanched this winter. HS around 50cm, no slab and weak.

Photos:

Location: Paradise Divide Area
Date of Observation: 12/18/2018
Name: Eric Murrow

Subject: South and Southwest bowls near Paradise Divide
Aspect: South East, South, South West
Elevation: 10,800′ – 12,450′

Avalanches:

Nothing new, but got a photo of a slide that was reported from the east side of Cinnamon last Thursday, This slide likely failed, 12/13 from heavy winds transporting the few inches of fresh snow that fell last Wednesday night, 12/12. This slide propagated across the entire eastern side of the summit terrain feature of Cinnamon.

Weather: Partly cloudy skies turning to mostly cloudy skies by about noon. Light snow started to fall around 2pm, but not hard enough to produce accumulations. Winds were out of the west and picked up with light gusting up to 15mph during the afternoon.

Snowpack: Poked around in two alpine bowls on S and SW aspects.

First, the SW bowl was generally blown off with exposed rocks transitioning to 25 to 40 of weak faceted snow with no Persistent Slab structure Present-some of this area was capped with a soft, weak crust.  This shallow or rocky condition covered 3/5ths of the bowl. As we traversed further into the bowl, north winds from the past week were able to drift snow on to a portion of the bowl because of the western ridge that defines that bowl. This ridge created a drifted seam of snow that ran down the length of the bowl. This seam of snow was a stack of dense wind slabs (1F+ and P- hard) around 100cm deep. Did not observe PSa structure present even in this drifted area but did not dig in the deepest area immediately behind the ridge feature. However, at the surface in this drifted area was a thin,3 to 10cm, wind/suncrust and immediately below was a thin layer of faceted snow. This structure does not currently present much hazard but with future loading could produce a Persistent Slab set up.

On the south bowl, we again found large areas of reduced HS from wind stripping. Probing across and down much of the slope and one quick pit did not showed Persistent Slab structure. Snow surface here was a suncrust around 3cm thick that was supportive to skis on steep slopes. This surface crust was resting on several centimeters of weak faceted snow below. This structure does not present a current hazard but if loaded with a substantial slab in the future it certainly would.

Take away from looking at these south and southwest alpine bowls was that no Persistent Slab structure present with the possible exception of drifted areas from crossloading. If you avoided the drifted crossloaded areas then you would very likely avoid any Persistent Slab structure.

Photos: