Avalanche Advisory Archive 2016 – 2018

Date Issued:2016-12-30 07:25:48
Danger:3
Primary Trend:3
Primary Probability:3
Primary Likelihood:3
Primary Size:2
Primary Description:

Two days ago Chop Gulley on Mt Juneau slid... this natural avalanche shows there is a weakness present in the snowpack in our region. The only question is does this weakness exist where I choose to recreate... and what additional load will be required for it to release? New Snow, Wind, or YOU as the trigger...

Todays forecast calls for a few inches of snow then heading into a wind event... be aware this windloading will bring that weak layer that much closer to failure.. we could see some natural avalanches out of this... but we definitely will be much closer to widespread human triggered slides if we see the windloading as expected.

Secondary Trend:3
Secondary Probability:4
Secondary Likelihood:3
Secondary Size:2
Secondary Description:

We have a persistent slab problem with this new snow resting on a layer of facets in places... when doing your own field assessments look for this weak layer in your tests... see if it is gaining any strength... but recognize this weak layer may exist for some time to come. Keep an eye out for it in the areas you choose to recreate.

Discussion:

The National Weather Service Forecasts-

Today- Becoming windy. Rain and snow developing. Snow accumulation to 1 inch. Highs around 38. Southeast wind 10 to 20 mph increasing to 20 to 30 mph with gusts to 45 mph in the afternoon.

Tonight- Widespread rain and snow showers diminishing late. Snow accumulation to 1 inch. Lows around 28. East wind 10 to 20 mph shifting to the north 15 to 25 mph late.

Saturday- Partly cloudy. Highs around 31. North wind 15 mph in the morning becoming light and variable.

Temperatures have remained fairly stable throughout the region over the last 24 hours with near freezing temps in place.

Eaglecrest saw a daily high of -2.5c while the tram came up to -1.1c. Currently Eaglecrest is showing -3c ant its -2.1c at the tram... Temps are supposed to fall over the next 24 hours in general... it will warm up early today with the precipitation but by early evening will begin falling. Temps should drop several degrees over the next 24 hours.

Precipitation remained light around the region yesterday giving the snowpack time to settle and bond a little bit... but its important to remember the faceted layer we started building from earlier this week with well over a foot of snow on that weak layer now in places. If this layer still exists where you are you will find a persistent weakness in the snowpack that may take time to heal... or may not heal at all depending on upcoming weather... Remember this is probably our greatest concern now... not so much new precip. The forecast calls for light precipitation over the next 12 hours delivering less than .5\" of water and less than 4\" of new snow even at upper elevations.

Winds have been fairly calm around the region but we did see periods of teens yesterday with some higher gusting... be aware that windloading has occurred on that storm slab... that is sitting on facets in places. This is a concern... especially as we see increased winds this afternoon into tomorrow. Wind forecasts for today call for 10mph winds increasing to 30+ out of the N tonight into tomorrow. This will bring a lot of additional loading to our urban environment and should be taken into consideration.

Currently danger is really more Moderate... but as we see new load and wind danger will build tonight to CONSIDERABLE.

Natural avalanches possible; human-triggered avalanches likely.

Be increasingly cautious in or under steeper terrain and in avalanche zones. Monitor avalanche forecasts.

Tonight and tomorrow are probably great times to avoid walking your dog in the gated areas above the Berhands Neighborhood.

Limit your exposure by limiting your time in Avalanche Terrain.

Tip:

To understand a persistent weak layer and to identify if one exists in the area you choose to play it is important to conduct periodic snow tests.

Here is a link to Snowpit Tests from the National Avalanche Center you should be aware of how to conduct these tests.

Forecaster:Tom Mattice