Storm observations from Upper Slater River Valley

CB Avalanche Center 2018-19 Observations

Location: Paradise Divide Area
Date of Observation: 11/23/2018
Name: Eric Murrow & Evan Ross

Subject: Storm observations from Upper Slater River Valley
Aspect: North East, East, South East
Elevation: 9600′ – 11100′

Avalanches:

We skier triggered 4 Storm Snow avalanches, one of which was remotely triggered and was likely a D2 in size. Poor visibility and trees prevented viewing the debris.
A group riding earlier the morning in same terrain triggered a D1.5 as well.
We also saw two natural avalanches, D1.
All observed avalanches failed at the new/old interface and where easterly to northeasterly facing.

Spoke with a group of skiers, that ascended a ridge just adjacent to our up track, that said Purple Palace terrain had avalanched in multiple places. I did not view this terrain, but based on the slope size in this area these avalanches were likely close to D2 in size.

Weather:

Skies were overcast with light snow from 10am to 3pm, generally S1 snow with brief periods of S2. On our below tree line tour, winds were light with occasional moderate gusts. Visibility was poor but did see small amounts of snow transport.
Snowpack:

On the way out Slate River Valley, we stopped at Pittsburg, 9400′, at 1050am to measure the new storm snow and found 10″ of new snow with .8″SWE. On the way out we stopped back at Pittsburg at 315pm and measured 11.5″ storm total with .95″SWE. Much of the new snow was rimed particles with some graupel present.

On our tour we found new snow totals ranging from 10″ to 15″. The new snow was resting on very weak old snow on any aspects with even the slightest bit of north to it. The new snow was very reactive to the weight of a person. We triggered 4 slides, saw one other human triggered slide, and two natural slides. Mostly D1.5 in size, given the generally small terrain features we were on. I imagine that on larger slopes avalanches would have reached D2 in size (large enough to bury a person). Several of the avalanches were triggered remotely from 75′ to 100′ away; impressive for storm snow that was fist dense(very soft). We descended east facing terrain back to snowmo’s and saw cracking within the new snow on descent that wasn’t present while ascending. The storm snow was sitting on melt/freeze crusts  and large facets on this east aspect.

At the end of the day, we rode machines part way up Paradise Divide road until we were shut down by soft, large drifts up to 4′ thick on the road surface. On our tour we saw minimal evidence of loading below tree line, but riding up the road through the open the impact of the wind was obvious.

Photos: