Calm Before the Storm

Location Name: 
Williams Lake Area
Region: 
Williams Lake Area
Date and time of observation: 
Sat, 01/20/2018 - 12:02
Location Map: 
United States
36° 32' 56.6124" N, 105° 25' 45.3648" W
US


Red Flags: 
Obvious avalanche path

Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Went for a walk before the storm tonight and tomorrow.  Another week of high pressure has done a lot leaving snow just on northerly aspects above 11,000' . Most of the terrain is back to bare ground.  It sounds like a broken record but we just haven't been able to build up a base on solar aspects.  Did a lot of walking and quick digging to see what the different types of snowpacks look like.  Right now we could describe it as a very thin, weak and highly variable snowpack on northerly aspects.  Near treeline has mostly cohesion-less facets with no slab on top.  These depths range anywhere from 2" to 16" . Above treeline we have snow lingering since November.  A shallow snowpack and cold temps have really driven the faceting process and we have well developed depth hoar (sugar-like) snow on the ground that has some form of wind slab on it from previous wind/snow events.  These depths typically range from 1 to 3' and have an incredibly poor snowpack structure.  Often times we are getting failure on isolation when conducting stability tests.   We did not observe any cracking or collapsing, but I expect that to change tomorrow when we add more weight and stress to the snowpack.  

The tricky part will be that with snow in forecast and fresh coat of white tomorrow, it's not going to be obvious where the existing snow was.  Fortunately we don't have many continuous snow slopes with persistent slabs.  However, with our spatial variability we have a lot of likely trigger points that won't be so obvious.  

Photo 1: A cross-loaded gully that has a up to 4' of snow in it.  We have a supportable slab in spots that is sitting on top of weak layers.  Notice that you would be more likely to trigger an avalanche where the slab is shallower on the left hand side.  Right now it is obvious where it is shallow, but with the potential of over a foot of new snow that won't be so obvious.

Photo 2: A 2' deep snowpack with the obvious depth hoar on the bottom and slab on top.  We got an ECTC with failure on isolation.

Photo 3: The concern tomorrow will be where the new snow is falling and accumulating on the old snow.  Here's an example of chute that is holding snow on the skiers right side but not the left.  

Photo 4: A shallow mostly faceted snow pack.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Light
Air temperature trend: 
Warming
Wind Direction: 
Southwest
More detailed information about the weather: 

Pretty incredible that it's T-Shirt weather and we'll be in a winter storm warning tonight at 8PM.  Although temperatures were warm, we are still not getting above freezing above 11,000' keeping the snow cold.  There is a drastic difference between the sun and shade right now.