Avalanche Advisory Archive Pre-2016

Date Issued:2014-02-28
Danger:2
Trend:3
Probability:0
Size:2
Problem:0
Discussion:

... STRONG WIND THROUGH SATURDAY MORNING ...

TODAY ... CLEAR ... LOCALLY WINDY. HIGHS 35 TO 43. NEAR DOWNTOWN JUNEAU AND DOUGLAS ... NORTHEAST WIND 15 TO 25 MPH WITH GUSTS UP TO 40 MPH. ELSEWHERE SOUTHEAST WIND 5 TO 15 MPH.

TONIGHT ... CLEAR. LOCALLY WINDY. LOWS 15 TO 23 ... EXCEPT AROUND 9 ABOVE IN WIND SHELTERED AREAS. NEAR DOWNTOWN JUNEAU AND DOUGLAS ... NORTHEAST WIND 25 MPH WITH GUSTS TO AROUND 40 MPH. ELSEWHERE ... LIGHT WINDS.

SATURDAY ... SUNNY ... LOCALLY WINDY. HIGHS AROUND 32. NEAR DOWNTOWN JUNEAU AND DOUGLAS ... NORTHEAST WIND 15 TO 25 MPH WITH GUSTS UP TO 40 MPH IN THE MORNING. OTHERWISE NORTHEAST WIND 5 TO 15 MPH.

No new precip. Winds have held steady out of the SE. Temps finally dropped back below freezing at the Tram around 2am last night.

Surface hoar is likely to be forming in wind sheltered areas tonight. The Crust/Facet combo responsible for our last avalanche cycle still persists above Pittmans ridge on Douglas.

Hazard remains at Low for the Urban zones, except for the chance of warm, wet, point releases above the Flume and Perseverance area which still have the potential to step down into either wind slabs or the faceted layer just above the big Melt-Freeze Crust.

So, the hazard is MODERATE today: Natural avalanches unlikely; human-triggered avalanches possible. Use caution in or under steeper terrain and in avalanche zones. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Tip:

SETTLEMENT AND SINTERING:

A newborn, snowflake that falls out of the sky doesn't stay that way for long. As soon as it lands on the snow surface it begins a rapid process of change. Just like people, as a snowflake ages, its beautiful, angular shape becomes progressively more rounded through time and it forms bonds with its neighbors. In people, it's called growing up; in the snowpack it's called \"sintering\"--forming bonds with neighboring crystals to create the fabric of the snowpack.

As sintering progresses, the snow becomes denser and stronger, which we call \"settlement.\" Sometimes you will hear people incorrectly use the term settlement to describe the catastrophic collapse of a snowpack that often makes a giant \"whoomph\" sound, as in, \"Hey, did you hear that settlement? Maybe we should get out of here.\" Instead, we call these collapses or \"whoomphing\", which, believe it or not, is actually the technical term for a collapsing snowpack. It sounds funny but it's a great description. Settlement is the SLOW deformation of the snow as it densifies and sags under the influence of gravity.

New, fluffy snow settles relatively quickly, within minutes to hours and it settles much more quickly at warm temperatures than in cold temperatures. We often think of settlement within the new snow as a sign of stability (at least within the new snow) because it means that the new snow is rapidly becoming stronger. When new snow settles, it forms \"settlement cones\" around trees and bushes where the snow bonds to the bush which props up the snow, like a circus tent.

Forecaster:Chris Eckel