Avalanche Advisory Archive Pre-2016

Date Issued:2014-04-12
Danger:1
Trend:2
Probability:0
Size:2
Problem:0
Discussion:

TODAY...MOSTLY SUNNY. HIGHS AROUND 52. LIGHT WINDS BECOMING SOUTHEAST 5 MPH IN THE AFTERNOON.

TONIGHT...PARTLY CLOUDY. LOWS AROUND 28. LIGHT WINDS.

SUNDAY...PARTLY CLOUDY. HIGHS AROUND 54. NORTHEAST WIND 5 MPH IN THE MORNING BECOMING LIGHT AND VARIABLE.

Yesterday temperatures reached 3.3C(38F) at the Tram and 1.1C(34F) at Eaglecrest. All stations reported temperatures below freezing last night with Eaglecrest being the coldest at -14C(6F). Winds were calm at all stations after midnight.

Today looks to be another beautiful spring day with abundant sunshine. Remember on days with strong diurnal warming it is best to travel through avalanche terrain in the morning when the snow has refrozen from the previous days solar warming. With light winds and strong solar warming I expect to see some small wet avalanches in the heat of the day. These slides should remain small in size.

Fieldwork yesterday found many alternating layers of wet and moist snow that was capped by a thin melt freeze crust. With light northerly winds the snow surface remained relatively cool in wind-affected areas. The snow was relatively un-reactive to stability tests.

The avalanche danger today is LOW but may reach MODERATE this afternoon as temperatures reach the mid 40?s in our upper start zones. Remember to minimize exposure in avalanche runouts in the heat of the day when wet slides normally occur.

This is not a backcountry forecast. Backcountry travelers be sure to do your own terrain and snowpack evaluation as spatial variability exits.

Have a great day!

Tip:

Powder magazine?s website has a good article on wet slides in the backcountry.

?Spring is in the Northern hemisphere, meaning the days are longer and the coverage is better. Weak layers from the early season are still around in some remote areas, but most have either gained strength, been scrubbed out by full-depth releases, or are too deep to be triggered by most skiers. It?s time to shift focus towards a new enemy in the backcountry?wet slides. These types of avalanches generally occur after the sun does its work on freshly fallen snow or when we enter extended periods of warm weather and poor refreezing. At this point, remember that everything happens faster at warmer temps.

The anatomy of a wet snow avalanche is very similar to that of a dry snow avalanche. The main difference is that in a wet slide, the weak layer is being further weakened rather than overloaded.

This weakening is the result of free water in the snowpack. It can come from a warm storm where rain falls on snow, or when intense sun bakes the snow. The free water percolates down through the snowpack and saturates the slab, causing it to settle and creep downhill with the force of gravity.?

Find the full article at http://www.powdermag.com/avalanche-education/backcountry-essentials-wet-slides/

Forecaster:Pat Dryer