Avalanche Advisory Archive Pre-2016

Date Issued:2010-02-06
Danger:1
Trend:3
Probability:1
Size:1
Problem:0
Discussion:

The National Weather Service Forecasts- TODAY...CLOUDY. A 20 PERCENT CHANCE OF RAIN AND SNOW IN THE AFTERNOON. HIGHS AROUND 37. EAST WIND INCREASING TO 15 MPH IN THE AFTERNOON.

TONIGHT...MOSTLY CLOUDY. A CHANCE OF RAIN AND SNOW IN THE
EVENING...THEN A CHANCE OF SNOW LATE. LOWS 26 TO 32. EAST WIND 15 MPH. CHANCE OF PRECIPITATION 50 PERCENT.

WEDNESDAY...SNOW AND RAIN LIKELY IN THE MORNING...THEN RAIN
LIKELY IN THE AFTERNOON. SNOW ACCUMULATION UP TO 1 INCH. SNOW
LEVEL 1000 FEET IN THE AFTERNOON. HIGHS AROUND 38. EAST WIND
15 MPH. CHANCE OF PRECIPITATION 60 PERCENT.

With very little new snow in the last week and the cooler temperatures in place, things are farily stable at this time.

We have seen more above freezing temperature on Mt Roberts and Mt Juneau than below freezing temperatures in the last week. This was slowly weekening the snowpack. We have seen cooler temperatures in the last 48 hours which is starting to solidify the snowpack in place

As long as rain or snow comes in slowly or not at all danger levels should remain Low.

Currently at lower elevations the bottom 2/3 of the snowpack is moist, warm, and rotten. There is some bonding and bridging above this layer. Yet the weakness is quite present and needs quite a bit of time at below freezing temperatures if it is to resolidify 100%.

Do to the continued rains and above freezing temperatures we are starting to be concerned with free moinsture in the snowpack. This moisture continues to eat at the bonds in the snowpack. Areas on steep open slopes are becoming more suspect. Thin snow cover on rocks in places may start to clean off as well. Also watch slopes with glide cracks as the prolonged temps can cause rapid glide activity which will add increased stress to the slabs in place. Backcountry danger may be higher in places. The cooler temperatures last night have started to freeze the pack back up a bit more.

Tip:

Below freezing temperatures are like the glue that helps to hold the snowpack together. During periods of above freezing temperature the bonds that have formed between the crystals erode and disappear. The longer the period of warm temperature the more the snowpack tends to weaken.

Rain has this same effect by rapidly warming the snowpack as well as eating away at the corners of the flakes and the bonds holding them together.

Once the snowpack warms it takes a tremendous amount of time and energy to bring it back down in temperature.

The most recent snow came in as rain and slowly turned into snow. This warm snow sticks well to the old snow surface. Today we will start to again see warmer temperatures. Look to see avalanche danger levels rise as the temps start to warm back up during periods of continued rain.

As we move towards tomorrow with continued cooling things will start to stabilize more..