The National Weather Service Forecasts-

TODAY...RAIN. PATCHY FOG IN THE AFTERNOON. SNOW LEVEL 700 FEET. HIGHS AROUND 38. SOUTHEAST WIND 10 TO 20 MPH WITH GUSTS TO 30 MPH DECREASING TO 10 MPH IN THE LATE MORNING.

TONIGHT...PATCHY FOG. RAIN IN THE EVENING. SNOW SHOWERS LIKELY LATE. SNOW ACCUMULATION TO 1 INCH. SNOW LEVEL 200 FEET LOWERING TO TO THE SURFACE. LOWS 25 TO 31. SOUTHEAST WIND 10 MPH.

SUNDAY...SNOW SHOWERS LIKELY. SNOW ACCUMULATION 1 TO 2 INCHES. HIGHS AROUND 32. NORTHEAST WIND 10 MPH.

We received just over an inch (.26mm) of precipitation in the last 24 hours at the Mt Roberts Tram summit during which time we saw about 8\" of new snow (20cm). This is showing quite a dense snowfall event.

During this same time winds blew from 20-50mph out of the SSE and temperatures rose by about 2c degrees.

This is quite a heavy dense snowfall event driven by high winds with a slight upside down trend.

Look to see slabs on Leeward slopes.

These slabs are coming to rest on a snowpack that still has some heavy dense surface layers overlaying the early season soft cold snow. This creates a weakness in the snowpack. We also have some layers of facets still in place from the early season cold that need to be taken into consideration. We have all the ingredients for an avalanche if you apply a heavy enough trigger.

Avalanche danger is Considerable at this time and falling slightly over tonight into tomorrow as we see some gentle cooling and a reduction in precip rates.

Natural avalanches possible in areas but the trigger is decreasing with less precip and cooling temps.

Remember for human triggered avalanches you are the trigger so the possibility of human triggered slides is always greater than for naturals.

Potentially destructive avalanches are still not likely to come near or reach developed areas. We just dont have enough snowpack on the mountain yet to trigger an event of this nature.

Human triggered avalanches probable especially in windloaded areas near summit and ridgeline.

Be aware of convex rolls, steep unsupported slopes, and terrain traps. Choose your routes carefully.

Trigger:

Most avalanches are ?naturally? triggered, meaning that weather (wind, snow, rain or sun) stress the snowpack to its breaking point.

Like a tree falling in the woods, for the most part, we only care about the ones that affect people. Luckily, in 92 percent of avalanche accidents, the avalanche is triggered by the victim or someone in the victim?s party.

In other words, most avalanche accidents happen by choice, not chance. These are ?human triggered? avalanches. In other words, weather adds stress to the snowpack until it nearly equals the strength of the snowpack. Then, the added weight of a person provides the final thump to initiate a fracture within the buried weak layer. (No, noise does NOT trigger avalanches. It?s a clich? plot device in the movies, but noise is simply not enough force to trigger an avalanche.)

When thinking about avalanche danger consider the Trigger Size Required to Initiate an Avalanche:

Large Cornice?

Explosive?

Human?

Natural?

We can also think of snow stability in terms of the size of trigger required to trigger an avalanche. Notice that when natural avalanches are occurring, the stability meter is pegged out at the top of the scale. That?s why the best sign of avalanche danger is another avalanche on a similar slope.