Avalanche Advisory Archive 2016 – 2018

Date Issued:2017-01-14 05:52:11
Danger:4
Primary Trend:3
Primary Probability:3
Primary Likelihood:4
Primary Size:2
Primary Description:

Winds have been howling around the region during this event.

We have seen consistent winds from 30-70+MPH.

This windloading is the primary concern.

This could build great slab depths in those windloaded areas.

Be aware folks this layer will be VERY trigger sensative today.

Secondary Trend:3
Secondary Probability:7
Secondary Likelihood:3
Secondary Size:2
Secondary Description:

Todays warming to above freezing temps makes us start to think of WET SLAB avalanches...

Are these truly wet slabs or are they storm slabs that are becoming moist... we could debate... but it takes a look at the slab at the time of failure to determine...

Simply be aware that as temps warm above freezing all this new snow and bonding comes into question.

Also be aware that as temps go above freezing previously stable layers deeper in the snowpack become questionalbe today. These could be quite large slides in places... Please avoid large avalanche paths with high exposure... also avoid steep convex slopes with increase stress. This is not an avalanche you want to be involved with.

Limit your danger by limiting your exposure.

Discussion:

The National Weather Service Forecasts-

Today- Windy. Rain...heavy at times. Highs around 42. Southeast wind 25 mph decreasing to 10 to 20 mph in the afternoon. Wind gusts up to 40 mph in the morning.

Tonight- Widespread rain showers. Lows 33 to 39. South wind 10 to 20 mph.

Sunday- Very windy. Rain. Snow level 1100 feet decreasing to 700 feet in the afternoon. Highs around 38. Southeast wind 10 to 20 mph increasing to 40 mph with gusts to around 55 mph in the afternoon.

Good morning Juneau Residents... Its a wet one out there. We have received 2.75\" of precipitation in the last 24 hours at the Eaglecrest mid mountain snow site. Mt Roberts is showing a little less with only 1.53\". This delivered a fair amount of VERY WET SNOW. Eaglecrest is showing 7\" of new at nearly 43% densities which is 3-4 times normal moisture content. Mt Roberts is much the same showing nearly 30% densities. This is a tremendous amount of snow and weight load being added to the current snowpack in place.

Also this wet snow creates conditions which are hard to predict. The snow volumes are not that high but the moisture contents are. This free water in the snowpack may bring us that much closer to a natural state of failure with Wet Snow Avalanches.

Winds have been howling around the region during this event from the S/SE. We have seen consistent winds from 30-70+MPH. This windloading is the primary concern. This combination of 2.75\" of precipitation and High winds leads to serious loading in our starting zones. Even though we only have 8\" of new snow this could easily be 2-3+ feet in wind loaded areas near summit and ridgeline.

Temperatures around the region have also risen by several degrees right to the point of freezing. Bringing us that much closer to a natural state of failure with Wet Avalanches.

Be Aware danger around the region is HIGH today. Natural avalanches are likely and human triggered avalanches are more than likely.

With this wet snow and massive new load we could also see previous weak layers come back into play. Be aware should this occur these slides could be VERY large and hard slabs which are very difficult to deal with and very deadly.

Tip:

Here is a great link to an article on Rain on Snow Avalanche Events.

http://arc.lib.montana.edu/snow-science/objects/issw-1988-125-136.pdf

Forecaster:Tom Mattice