Avalanche Advisory Archive 2016 – 2018

Date Issued:2017-01-16 06:42:19
Danger:4
Primary Trend:1
Primary Probability:7
Primary Likelihood:3
Primary Size:2
Primary Description:

With 5.5\" of precipitation over the last 5 days and the last half of that coming in the form of rain to our mountain summits...

Be aware that wet slab avalanche activity is possible if not likely depending on slope shape and anchors.

Start to look for glide cracks... these would be tell tale signs of areas of instability. We have not seen many glide cracks around the region this year but I would not be suprised to see new ones opening up today and in the coming days.

Remember areas with glide cracks should be avoided.

Secondary Trend:1
Secondary Probability:6
Secondary Likelihood:3
Secondary Size:2
Secondary Description:

It wont take much snow peeling off trees and rocks to get wet loose avalanches started today. Especially in steep open areas.

Be aware these can entrain a great deal of snow on our longer steeper pitches and should be avoided.

Limit your danger by limiting your exposure to terrain over the next 24 hours. By tomorrow this condition should subside.

Discussion:

The National Weather Service Forecasts-

Today- Windy...rain...heavy at times. Highs 38 to 43 early. Southeast wind 20 to 30 mph decreasing to 10 to 20 mph late morning. South wind 35 mph with gusts up to 50 mph near downtown juneau and douglas.

Tonight- Colder. Rain...changing to snow in the evening. Snow. Snow accumulation 1 to 2 inches. Snow level 900 feet in the evening. Lows 29 to 31. Southeast wind 10 to 20 mph.

Tuesday- Decreasing clouds. Slight chance of snow in the morning. Highs 32 to 38. Southeast wind 10 mph shifting to the north in the afternoon.

Temperatures remain quite warm around the region this morning with Mt Roberts tram summit showing 33f and Eaglecrest showing 32f at their mid mountain gauge. The base area is showing 34f and the summit is at 31f. Temperatures have been mostly above freezing for the last 48 hours in our mountain zones. The starts eating at the bonds in the snowpack.

We have seen a tremendous amount of rain around the region over the last 5 days as well. Typically if you see 1\" or more a day of precipitation that is significant loading to your snowpack. We have seen 5.5\" over 5 days which is very definitely cause for concern. This system started at near freezing temperatures. The snowpack was quite moisture saturated... and with 2.5\" of the 5\" all coming in during the rain to summit our snowpack is now VERY MOISTURE SATURATED.

Winds build some weakness in the starting zones at the beginning of our systems but that snow has mostly all been wetted out and is much like the rest.

The snowpack is starting to get rotten... Especially at mid to lower mountain elevations. Todays forecast calls for another 1.3\" of precip and continued warm temps. Be aware danger today is HIGH.

Natural avalanches are likely and human triggered avalanches are more than likely on steep open convex slopes... Unsupported slopes, large convex rolls, areas with few or no anchors like slabs on rock or grassy areas will be suspect today.

It also wont take much in the way of snow falling off trees or rocks to entrain additional mass as it cleans itself off of the steeper slopes.

As we go into tomorrow temperatures are to fall by 4-6 degrees and the snowpack should start to stabilize over time. Precipitation rates are also falling and this will also help bonding as the snowpack settles, drains, and freezes back up.

Be aware to avoid big exposure today. Its a good day to play it safe and know tomorrow will have better conditions for safety purposes.

Tip:

Wet Snow Avalanche

An avalanche caused by snow losing its strength after becoming damp, moist or saturated with water.

Wet Snow Avalanche:

Most avalanche professionals make a hard distinction between dry snow and wet snow avalanches because they are such different beasts. They are caused by different processes, they fail and fracture differently, they are triggered differently and they move differently down the slope. Really, there is a continuum between wet and dry avalanches and professional workers use the words: dry, damp, moist, wet and saturated to describe the continuum. Wet avalanches cause relatively few avalanche fatalities, consequently, they are studied less and are not as well understood

Forecaster:Tom Mattice