Avalanche Advisory Archive Pre-2016

Date Issued:2014-03-28
Danger:2
Trend:3
Probability:0
Size:2
Problem:0
Discussion:

TODAY...SUNNY. HIGHS AROUND 40. LIGHT WINDS BECOMING EAST 5 TO 15 MPH LATE IN THE MORNING. NEAR DOWNTOWN JUNEAU AND DOUGLAS... NORTHEAST WIND 10 TO 25 MPH. HIGHER GUSTS IN THE AFTERNOON.

TONIGHT...MOSTLY CLEAR. LOWS 20 TO 28. EAST WIND 5 TO 15 MPH. NEAR DOWNTOWN JUNEAU AND DOUGLAS...NORTHEAST WIND 10 TO 20 MPH.

SATURDAY...SUNNY. HIGHS AROUND 42. NORTHEAST WIND 10 TO 20 MPH.

Temps remanded below freezing at all three ridge top weather stations in the past 24hours. Moderate to strong NE ridge top winds continue to transport snow in our upper start zones. Fieldwork yesterday confirmed that snow is being both scoured and deposited in our upper start zones. This will continue over the next 24 hours as winds are forecasted to increase this evening.

Main avalanche problems today are wind slabs and loose wet avalanches. Wind slabs will continue to build with the moderate winds forecasted for the next 24 hours. Isolated pockets of wind slab may release throughout the day. Fieldwork yesterday confirmed there are still isolated pockets of the persistent weak layer above the January crust in the urban start zones. These isolated pockets are not continuous enough to constitute a large problem for the urban paths. The sunshine and light winds during the day will allow for some strong solar radiation and may start some small wet slides in our upper start zones. I don?t anticipate these slides to be large at this time.

Please note that we compile this forecast by looking at snow data from all over our local mountain ranges, this forecast is targeted at the slide paths that impact CBJ homes, roads, and trails, and is not a general backcountry forecast. There is a lot of spatial variability out there right now, and our start zones are not representative of many of the areas where people recreate in the backcountry.

Backcountry travelers beware! There were large slides on Douglas this week: one skier triggered slide on Ben Stewart, which occurred after multiple tracks had been put on that slope The slide was believed to have slid on the persistent weak layer (facets) just above the thick Jan Crust.

Avalanche Danger for the urban zones is MODERATE: Natural avalanches unlikely; human-triggered avalanches possible. Small avalanches in specific areas; or large avalanches in isolated areas. The avalanche danger may approach CONSIDERABLE midday as small wet slides may release as a result of light winds and strong solar warming. Watch for updates if conditions warrant.

Tip:

Here is the definition of a loose wet avalanche from the Colorado Avalanche Information Center website.

Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.

Forecaster:Pat Dryer