...STRONG WIND THROUGH THIS AFTERNOON...

TODAY...RAIN IN THE MORNING...THEN CHANCE OF RAIN IN THE AFTERNOON. SNOW LEVEL 800 FEET. HIGHS AROUND 39. SOUTHEAST WIND 15 TO 30 MPH WITH GUSTS TO AROUND 45 MPH.

TONIGHT...COLDER. RAIN AND SNOW IN THE EVENING...THEN SNOW SHOWERS LATE. SNOW ACCUMULATION 1 TO 3 INCHES. LOWS 24 TO 30. SOUTHEAST WIND 10 TO 20 MPH BECOMING SOUTH 10 MPH LATE.

Back to winter. We have had 37mm of water fall as snow in the alpine since this storm began. By itself that would be almost a half meter of snow, but there has also been significant wind loading. Winds jumped up about 4pm yesterday and are just starting to show signs of coming back down now. They have been out of the SSE which is primarily cross-loading for the urban start zones.

This storm has had a steady increase in temp for it's duration which is forecast to continue today. This means that the light fluffy dry snow is on the bottom right above the solid melt-freeze crust and steadily warmer denser snow sits above it.

Yesterday there were small naturals on almost every small roll on Douglas between 1500 and 2200 ft. The high alpine there, and around town (when it was visible), seemed to have far fewer slides but it is the same snow stratigraphy.

It is already rain on snow in town, and while rain is not forecast at this time for our start zones, if the rain does rise that high it will lead to numerous natural slides.

Fortunately the total accumulation has not been large enough yet that these slides are likely to pose problems for structures or road ways. However even powder clouds can be destructive and great care should be taken by walkers particularly along Thane Rd and the Flume/Perseverance areas.

Natural Avalanches are possible becoming likely if the rain level rises high enough, but sizes are still of a smaller nature for the urban slide paths.

Human triggered avalanches are certain particularly on E-N-W aspects above 1500.

PRECIPITATION & TEMPERATURE
Precipitation

In the assessment of an avalanche threat, the amount of precipitation in combination with wind, temperature and the existing old snowpack constitute a central factor. Whether the amount of snow in a snowfall period (1-3 days) is to be assessed as critical or rather unproblematic, depends on the conditions during and immediately after the snowfall.

An amount of 10-20 cm of fresh snow, fallen with strong wind exposure at low temperatures on an old layer of melt-freeze crust can have a highly critical impact. On the other hand, fresh snowfall of 30 cm fallen on a wet layer with no wind and at a temperature of around 0?C at the beginning constitutes no significant increase in risk. Altitude and temperature profile during the precipitation have different effects on the avalanche situation, so this must be critically assessed.

Temperature

One of the basic conditions to be observed during and after the snowfall is the temperature. Cold, hot air and sunlight considerably affect the transformation processes in the snowpack and thus also the avalanche situation. Both the exact temperature itself as well as the temperature trend affect snow bonding in either a positive or negative way.

Considerable warming leads to very critical situations, but its impact can be well assessed.
Considerable warming
--

Slow, moderate warming promotes the settling of the snowpack and therewith the binding between the layers.
Slow, moderate warming
+

Warming during the day and cooling at night causes an ideal solidification of the snowpack, but an aggravation of the avalanche situation must be taken into account due to solar radiation during the day from E to W.
Warming during the day, cooling at night
++

Cold preserves existing hazards and delays the settlement.
Cold
-

Persistent, severe cold promotes the formation of floating snow (ball bearing effect) and surface hoar (covered by a critical weak layer of snow), resulting in a worsening of the situation.
Persistent, severe cold
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