Avalanche Advisory Archive Pre-2016
Date Issued: | 2013-04-17 |
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Danger: | 2 |
Trend: | 2 |
Probability: | 3 |
Size: | 2 |
Problem: | 0 |
Discussion: | The National Weather Service Forecasts- TODAY...RAIN. HIGHS AROUND 43. SOUTHEAST WIND 10 TO 20 MPH TONIGHT...MOSTLY CLOUDY. SCATTERED RAIN SHOWERS. SCATTERED SNOW SHOWERS LATE. LOWS AROUND 33. NORTHWEST WIND 10 MPH SHIFTING TO THE SOUTHEAST LATE. THURSDAY...MOSTLY CLOUDY. ISOLATED SNOW SHOWERS IN THE MORNING. ISOLATED RAIN SHOWERS IN THE AFTERNOON. HIGHS AROUND 48. NORTHEAST WIND 5 MPH. Temperatures cooled off to below the freezing point at the Mt Roberts Tram summit two nights ago. The same goes for Eaglecrest. EC is about -2c and the tram is slightly warmer then -1c. Temperatures are forecast to remain cool today with not much daytime warming and should drop slightly overnight again tonight. We have received 22mm of precip in the last 20 hours which left 20cm or about 8\" of new snow at the Mt Roberts Tram Summit. Eaglecrest mid mountain weather site received slightly less. Windloading was present with strong winds from 15-50mph. Winds were slightly higher on Douglas Island than at the Tram Summit. This traditional loading was out of the SSE. Be aware that the new wind slabs came to rest on what is probably an icy bed surface after last weekends sun. Avalanche danger is MODERATE at this time. Natural avalanches unlikely, potentially destructive avalanches unlikely to come near or reach developed areas. Human triggered avalanches possible to probable in windloaded areas. If you head into the mountains today use extreme caution in windloaded areas. With relatively cool temps in place and not that much precip in the forecast things should start to stabilize over time. Danger levels will fall slightly into tomorrow. Avoid windloaded zones over terrain traps. Give this new snowpack time to settle and bond. Stick to lower angle concave slopes in windsheltered areas and have a great day. |
Tip: | equitemperature (ET) metamorphism - the process of changes in snow texture from complex crystal shapes toward rounded snow (ice) grains in the absence of large temperature gradients. Technically this is known as destructive metamorphism (it destroys crystal shapes), and it results in a strengthening of the ice skeleton and a general rounding of snow grains largely through a preferential transfer of water vapor within the snowpack. |