Avalanche Advisory Archive Pre-2016

Date Issued:2011-02-13
Danger:2
Trend:4
Probability:3
Size:3
Problem:0
Discussion:

The National Weather Service Forecasts-

TODAY...SNOW. SNOW ACCUMULATION 3 TO 4 INCHES. HIGHS AROUND 35. SOUTHEAST WIND 10 TO 20 MPH.

TONIGHT...SNOW. SNOW ACCUMULATION 3 TO 4 INCHES. LOWS 24 TO 30. SOUTH WIND 10 TO 20 MPH.

MONDAY...BECOMING LOCALLY BREEZY...SNOW. SNOW ACCUMULATION 3 TO 5 INCHES. HIGHS AROUND 28. NORTHEAST WIND INCREASING TO 15 TO 25 MPH IN THE AFTERNOON.

MONDAY NIGHT...MOSTLY CLOUDY. LOCALLY WINDY. MUCH COLDER. SLIGHT CHANCE OF SNOW IN THE EVENING. LOWS 6 TO 16. NORTHEAST WIND INCREASING TO 20 TO 30 MPH WITH GUSTS TO AROUND 50 MPH IN THE EVENING NEAR DOWNTOWN JUNEAU AND DOUGLAS. OTHERWISE NORTHEAST WIND TO 15 MPH.

We have seen about 63 cm of snow(over 2') in the last 8 days after settlement. This came during a period of 135mm of moisture. As you can see this new slab of snow is quite dense (over 20% average).

The beginning of the storm started with snows of less than 10% density. During the storm those low density layers have been settling with the additional load on top of them. We have given this new snow layer several days to settle and bond both now.

Temperatures have fallen by several degrees in the last 2 days and are expected to continue falling over the next few days.

Precipitation rates have slowed considerably over the last few days are are expected to remail lower.

Windloading is still heavy out of the SE placing weak slabs on NW slopes and cross loading other areas. wind loading was moderate/strong throughout this entire storm.

There are still areas of weakness for certain but as this weakness gets further down in the snowpack it becomes harder to trigger. As this weak layer has additional time it continues to become stronger.

As the snowpack gains strength we also continue to load mass so the question remains is it getting stronger? Yes. How much stronger? Hard to say as we continue to add mass and create new weak layers with windloading in areas.

During the last week we have seen widespread natural and human triggered avalanche activity. Please be aware this is an obvious sign of a weak layer in the snowpack that is near a state of failure.

Please recognize the mouse trap has been set and even though danger levels have decreased slightly today there is still the ability to trigger avalanches.

As we go through today and into tomorrow with new snows and moderate to heavy windloading look to see new slabs develop on top of the deep slabs already in place. Danger levels are expected to rise during this period.

Avalanche Danger is MODERATE at this time.

Although natural avalanches are unlikely. Human triggered avalanches remain likely in areas.

Heightened avalanche conditions on specific terrain features exist. Please evaluate snow and terrain carefully while identifying features of concern.

Remember- Transceiver, Probe, Shovel, good partner.
Dont head into the backcountry without them.

Tip:

One thing to consider in operating in avalanche terrain is visibility.

While it may be relatively safe to analyze and ski a slope with CONSIDERABLE avalanche danger on a day with perfect visibility, multiple partners, and the proper equipment.

It may be considered much more dangerous to ski a slope where you can not see the entire avalanche path and runout even on a day with MODERATE avalanche conditions.

If you can not see the terrain features below you.

If you can not spot your partner from the top of the avalanche area all the way into the safe zone out the bottom or side.

If you can not see the last point seen once they get carried off in a slide.

If you can not see how far the avalanche area went or the line of travel it carries your partner off in.

Perhaps you should reconsider the level of danger you are operating in???

Be safe and enjoy a great day!