The avalanche forecast for Méteo France got it right when they predicated a rating of 3 for today and emphasising that a single skier could possibly set off a slab avalanche especially on steep slopes facing north to north east (the instability is due in large part to a significant weak layer on many slopes made up depth hoar and faceted grains - North facing slopes are especially effected, but just about all slopes above 2800 have a serious weak layer). At about 11.30 on the 21st a group of skiers set a nice one off above Val Claret on the big, NE facing slopes of the Grande Balme. See the tracks going into the slab on upper far right of photo below in the shade (double click on photo to enlarge it). Luckily no one was hurt.. Note the recent avalanche activity all along similar slopes... several other accidental avalanches occurred on similar slopes today without injuries that I know of. Watch out after the storm on Friday to Saturday. We're supposed to get 50 to 120 cm at 2500 metres in the northern French Alps. This will only add to the load on top of the weak layer in the snowpack and will be dangerous if you're not thinking about what you're doing. The clues revealing instability have been flagrant today (again see below).