10 Apr 2012

Even the winds from Sunday help to get cornices looking like this.                  R. Bougie Photo

At 2280 meters the temperature was 0, winds are 10-25 KPH from the ESE as of 06:00. At 1550 meters the temperature was +2, 70 % relative humidity, and the barometer is dropping slightly. No new snow, and in the valley it was 0.

For the Latest Avalanche Advisory click here: Avalanche Advisory

Speed kiting and ski cutting,  who would have thunk: Avalanche Control on the Fly

Urban Avalanche in Scotland: Roof Avalanche

Jeeps and Avalanches: Jeep Commercial

After the wild winds on Sunday thought I should bring up the topic of Anabatic and Katabatic Winds:

An anabatic wind, from the Greek anabatos, verbal of anabainein meaning moving upward, is a wind which blows up a steep slope or mountain side, driven by heating of the slope through insolation.[1][2] It is also known as an upslope flow. These winds typically occur during the daytime in calm sunny weather. A hill or mountain top will be radiatively warmed by the Sun which in turn heats the air just above it. Air at a similar altitude over an adjacentvalley or plain does not get warmed so much because of the greater distance to the ground below it. The effect may be enhanced if the lower lying ground is shaded by the mountain and so receives less heat.
The air over the hill top is now warmer than the air at a similar altitude around it and will rise through convection. This creates a lower pressure region into which the air at the bottom of the slope flows, causing the wind. It is common for the air rising from the tops of large mountains to reach a height where it cools adiabatically to below its dew point and forms cumulus clouds. These can then produce rain or even thunderstorms.[2]

katabatic wind, from the Greek word katabatikos meaning "going downhill", is the technical name for a drainage wind, a wind that carries high density air from a higher elevation down a slope under the force of gravity. Such winds are sometimes also called fall winds. Katabatic winds can rush down elevated slopes at hurricane speeds, but most are not that intense and many are on the order of 10 knots (18 km/h) or less.
Not all downslope winds are katabatic. For instance, winds such as the FoehnChinook or Bergwind, are rain shadow winds where air driven upslope on the windward side of a mountain range drops its moisture and descends leeward drier and warmer. Examples of true katabatic winds include the Bora (or Bura) in the Adriatic, the Bohemian Wind orBöhmwind in the Ore Mountains, the Mistral, the Santa Ana in southern California, the Tramontana and the Oroshi in Japan.

Yesterday I had mentioned the slide on Overlord, here is some information and pictures from Andre Charland. 

Location Description
Bottom of Overlord Glacier
Mountain Range
Coast Mountains

Backcountry Skiing
Skier traversed from flatter ridge heading skiers left into the middle of a moderate pitch convex slope that was wind loaded. A stiff slabbed release and the skier was able to ski out of it to the skiers right. It appeared to have released above the skier and step down a layer. Debris was large blocks up to 2m and very dense.

Date/timeSizeTypeTriggerElevationAspectSlab widthSlab thickness
2012-04-08 22:16 2SS1900w75m50cm 

Present TempMax TempMin Temp24hr TrendWind SpeedWind DirectionSky ConditionPrecipitation Type & Intensity
Weather comment
Very strong winds the night before from the east.
Snowpack24hr SnowStorm SnowStorm Date
Snowpack comment
Wind pack, however was blower the day before in none sun affected aspects.