Observation: White Pine

Observation Date
1/19/2016
Observer Name
Bruce Tremper
Region
Salt Lake » Little Cottonwood Canyon » White Pine
Location Name or Route
White Pine - Spire
Weather
Weather Comments
Clear in the morning with high clouds in the afternoon, thickening towards evening.
Snow Characteristics
New Snow Depth
12"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments

About of foot of powder from yesterday at upper elevations that were not wind affected with about 6 inches of powder at the trailhead. The new snow was quite good--settled to around 10%-- and it was laying on a spongy, denser, rimed layer of snow that was a bit slabby and upside down from the warming temperatures and wind a couple days ago.

We broke trail up to the Spire and skied 3 laps on 3 different aspects, northwest, north and northeast. All were about the same snow conditions.

It was great to be out without the hoards of weekend crowds. There was not too many people in White Pine. All the powder for ourselves, at least where we were.

Red Flags
Red Flags
Recent Avalanches
Red Flags Comments
I saw a number of storm slabs and sluffs within the new snow that came down during the storm yesterday. None appeared to be more recent than yesterday. (See photos below). The snow seemed to have settled quite a bit from yesterday.
Avalanche Problem #1
Problem
New Snow
Problem #1 Comments

I saw a number of storm slabs and sluffs within the new snow that came down during the storm yesterday. None appeared to be more recent than yesterday. (See photos below). The snow seemed to have settled quite a bit from yesterday. I did not get onto anything steeper than about 32 degrees but slope cuts did not produce anything on small rollovers. I saw terrain between the trailhead at 7,000' and the highest elevation around 10,000'. The upper ridge lines above 10,500' were quite wind blasted from the wind at the beginning of the storm yesterday. I'm guessing most of the storm slabs and sluffs came down during the high precipitation intensity and wind events during the storm. I'm uncertain of the weak layers because I'm not nearly as motivated to dig on the fracture lines of avalanches now that I'm retired. (You'll have to take it up with my wife and field partner--good luck with that.)

Avalanche Problem #2
Problem
Persistent Weak Layer
Problem #2 Comments

From the other observations, it's clear that the thin areas and/or repeater slide paths are a whole different animal than what I've been skiing in my conservative terrain choices. I was not in any areas that were probably repeater slide paths but I was across the valley from the Red Baldy shoulder that slid last week and there was no fresh avalanches on it, but there was no one up there provoking it either. I would definitely avoid any shallow areas or repeater slide paths with faceted snow just below all this storm snow. Especially with the added weight forecast for tonight and Wednesday, it might overload many of these fragile snowpacks. But the deeper areas seem pretty settled out and relatively stable, at least the places I've been going this past week. This is not based on snow profiles but just many probe poles and hasty arm pits. With more weight added tonight, it should keep things interesting on Wednesday.

Comments

A number of storm slabs on many of the steep slopes. Most are about 1' deep. Here you can see two of them on a steep, northwest facing slope around 9,000'.

North facing pocket, 9,400'

Quite a large storm slab on the west face of the Spire, around 9,800'. It's about a foot deep, perhaps 100 yards wide. All appear to have come down during the storm yesterday probably during the high precipitation intensity period. I don't know the weak layer but I'm assuming it was the pre-existing snow surface--a low density layer--perhaps slightly faceted.

A side view of the last photo.

Some widespread sluffing during the storm, this on the steep north face of the Spire.

More widespread sluffing on the steep east faces of the White Pine - Red Pine ridge.

The wind damage above about 10,500' along the ridges--this one on the Tri Chutes.

Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Considerable