Avalanche Advisory Archive 2016 – 2018

Date Issued:2017-03-30 06:10:54
Primary Trend:3
Primary Probability:6
Primary Likelihood:3
Primary Size:1
Primary Description:

With new snow at mid to upper elevations and diurnal fluctuations bring up the mid day temps to above freezing in places expect to see small wet loose avalanches as trees and rocks clean themselves off.

This near freezing snowpack will snow signs of near surface instability throughout the day at increasing elevations as we see warming.

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

The persistent weakness remains in the region.

All this new snow and rain at lower elevations continues to add load to the snowpack keeping us near a state of natural instability.

Any little wet loose slide, human triggers, more snow, rain, windloading.. can all be enough to trigger this deeper instability in the region.

Yesterday natural avalanches were sighted again on this weak layer. These are becoming quite large slides.

Limit your exposure to extreme terrain and recognize this instability remains.


The National Weather Service Forecasts-

Today- Cloudy. Scattered rain showers. Highs around 42. Southeast wind 10 mph.

Tonight- Rain. Lows around 41. Southeast wind 10 to 20 mph.

Friday- Rain. Highs around 44. Southeast wind 10 to 20 mph.

Good Morning Juneau. Avalanche Danger remains CONSIDERABLE today. Both Natural and Human triggered avalanches are possible.

Temperatures remain very warm around the region. The Mt Roberts Tram summit is 33f this morning. It has only been below freezing 3 hours since Sunday morning. Eaglecrest is 34 at the base, 31f mid mountain and 30f on top.

We picked up a fair amount of moisture yesterday. Eaglecrest is showing 21mm (.8\") and Mt Roberts is less with around 15mm.
Eaglecrest received 7cm of snow at that elevation and more at higher elevations. The Tram was warmer and picked up 4cm. This snow was 30+% density. It was very wet and heavy.

Winds were moderate over the last day blowing 15-25 on Douglas. and slightly less along the channel.

So with several days of warming the lower elevation snowpack especially along the channel is becoming quite warm and moisture saturated, increasing the risk for wet loose avalanches. At elevations with new snow the snow will bond well to the old snow surface... yet with diurnal fluctuations and daily temps increasing higher and higher on the mountain you will see this new snow falling off trees, rocks, and cleaning itself off... this can easily trigger wet loose avalanches in these areas.

At higher elevations where you have more snow you have a different animal building. We have seen several small storms over the last few days including wind at times. Look for windslabs on N to W aspects.

All this is also adding continued load and stress to the persistent weak layer in place. Natural avalanches occurred again yesterday in our region on this deeper instability. These remain quite large hard slab avalanches now. Be careful in steeper terrain in places that have not recently slid. Remember although low probability these are high consequence slides.

All this adds up to a snowpack that has the ability to move... and its important to recognize any activity... even small wet loose sluffs can be enough to trigger the deeper instability.

With temps that have not gone below freezing in several days along the channel best to avoid foot traffic on the Flume trail today.

The forecast calls for light moisture early in the day then increasing heavily overnight. This will rapidly increase danger levels. Tomorrow temps are forecast to rise to a new spring high for us. Large volumes of rain are also predicted. Avalanche danger will rise additionally tomorrow.

Be safe out there and have a great day.

Forecaster:Tom Mattice