Avalanche Advisory Archive Pre-2016

Date Issued:2010-12-13
Danger:1
Trend:4
Probability:3
Size:1
Problem:0
Discussion:

The National Weather Service Forecasts- WINTER STORM WARNING REMAINS IN EFFECT UNTIL 4 PM AKST THIS AFTERNOON...

TODAY...SNOW. SNOW ACCUMULATION 4 TO 8 INCHES. STORM TOTAL SNOW ACCUMULATION OF 5 TO 8 INCHES. HIGHS 26 TO 32. NORTH WIND 10 TO 20 MPH.

TONIGHT...SNOW LIKELY. SNOW ACCUMULATION 1 TO 4 INCHES. LOWS 17 TO 25. EAST WIND 10 TO 20 MPH.

TUESDAY...PARTLY CLOUDY. SLIGHT CHANCE OF SNOW IN THE MORNING. HIGHS 23 TO 29. SOUTHEAST WIND 10 TO 20 MPH.

With this last 10 days warm weather, the rain and heavy dense snow from two weekends ago, the snowpack had settled and bonded quite a bit.

There are still multiple weak layers further down in the snowpack but the heavy dense snow above them appears to be supportive at this time. Be cautious as new loads are placed on these already weak layers.

We had several inches of new snow deposited Saturday. This new snow came in during a period where temperatures came up by an average of 5 degrees and there was moderate wind loading. This has placed additional weakness in the snowpack in places with wind deposits.

Look to see continued areas of wind loading as the new snow deposits come in accompanied by winds of 10+ MPH throughout most of this coming cycle.

With very little snow on Mt Juneau in the urban starting zones avalanche danger is LOW at this time.

Please remember this is not a backcountry forecast.

Please be aware that fieldwork continues to show multiple weak layers in the snowpack. Backcountry danger levels could be considerably higher. Especially as this new snow comes in with the wind loading on the questionable weak layers already in place..

Not much snow has accumulated so far in this most recent storm. Forecaster's confidence in the amount of precip is low. But look to see danger levels rise even faster if this new snow starts to add up.

Tip:

Winds change snow stability.

Windward slopes often become packed. This can lead to hard slab avalanches. Yet after long periods of high winds the windward slopes can become scoured of snow leaving them safe for travel.

Lee slopes often see snow deposited from storm winds. This is a common cause of slab avalanches.

If you are seeing winds of 10+ MPH in the forecast you should be thinking of their effects on the slope in relation to aspect and elevation.

Remember during periods of snow fall. Rising temperatures place heavy dense snow above the looser lighter snow that fell at cooler temperatures.

Common signs of instability include rising temperatures throughout a storm cycle.