Avalanche Advisory Archive Pre-2016
| Date Issued: | 2014-01-23 |
|---|---|
| Danger: | 1 |
| Trend: | 3 |
| Probability: | 0 |
| Size: | 1 |
| Problem: | 0 |
| Discussion: | The National Weather Service Forecasts- TODAY...RAIN. HIGHS AROUND 49. SOUTHEAST WIND 15 TO 25 MPH TONIGHT...MOSTLY CLOUDY. AREAS OF FOG. CHANCE OF RAIN. LOWS 36 TO 42. EAST WIND 10 MPH. FRIDAY...DECREASING CLOUDS. AREAS OF FOG IN THE MORNING. HIGHS AROUND 43. SOUTHEAST WIND 10 MPH SHIFTING TO THE NORTHWEST IN THE AFTERNOON. Temperatures continue to remain quite warm. Temperatures have remained essentially above freezing at the Mt Roberts Tram Summit since 1/13/14. Temps have dipped below freezing but only for a few hours here and there. The Eaglecrest Summit has been above freezing 5 out of the last 8 days. Since the temps warmed on the 13th we have received 8.6\" of rain at the Mt Roberts Tram Summit and the drainage channels are now well established in the snowpack. We have lost nearly 80cm of snow since that time at the Tram Summit Wx Station. Small wet avalanches remain possible but should not be large enough to pose a threat to the urban enviroment. Glade rates have accelorated and we have seen a number of glide avalanches in the region. Be increasingly cautious is you choose to play in terrain that has evidence of snowpack gliding above it. Look for open glide cracks to give you a better idea of areas to avoid. These avalanches are very hard to predict yet be aware that during these continued warm temps danger is lingering in those areas. |
| Tip: | Recognize and Survive Wet Snow Avalanche Conditions. Two primary types of avalanches are slab avalanches and loose-snow avalanches, which begin at a point source and can occur with wet or dry snow conditions. Wet loose-snow avalanches, or wet avalanches, are encountered more frequently in spring and summer conditions as temperatures warm up and saturate the snowpack with water. Wet avalanches can move slowly down a slope from its trigger point, usually spreading out in an inverted V configuration. But wet avalanches become even more dangerous when they load a snow-covered slope and then cause its underlying slab to give way. For this reason, a wet avalanche may lead to a larger and more dangerous slab avalanche. Recognize Wet Snow Avalanche Conditions As with other types of avalanches, knowledge of the Avalanche Triangle is important in helping you to evaluate avalanche danger. The Avalanche Triangle includes the key factors leading to avalanches: snowpack, weather, terrain, and human interaction. Whereas dry snow avalanches occur when additional stress is put on the snowpack, wet avalanches occur as the snowpack strength decreases. Wet snow avalanche conditions develop when the snowpack is loose and saturated or moist with water. Water keeps the snowpack from consolidating in a stable manner; instead, snow becomes loosely associated and has a higher chance of sliding. Spring weather contributes to wet avalanche conditions, especially when a storm causes rain instead of snow to fall on snow slopes. Rain adds weight to the snowpack, and it can also warm up the snow, causing additional melting. Rain can also saturate the snow, lubricating the layers, and making it easier for an avalanche to occur. Wind is one of the most important weather factors to consider when evaluating dry avalanche danger since wind causes snowdrift and snow loading. But rain, melting caused by prolonged sun exposure, and warm temperatures are the more important weather factors to consider when evaluating wet avalanche potential. Terrain variables including slope steepness, slope configuration, and slope aspect are important to consider when evaluating avalanche hazards, in general, but also consider how these variables contribute specifically to wet avalanche hazards. Slope aspect, or the direction a slope faces, is an important factor to consider in spring or summer conditions. South-facing slopes receives more sun; therefore, south-facing slopes will be more prone to wet snow avalanches even though they are often considered to be more stable in the winter. Slope aspect considerations change significantly from winter to spring, so check local avalanche forecasts carefully. Survive a Wet Snow Avalanche Wet avalanches are most often triggered naturally, and they are more difficult for humans to trigger. In contrast, most of dry avalanches are caused by the avalanche victim or someone in the victim?s party, with some statistics citing human involvement in 90 percent of dry avalanche cases. Prepare for wet avalanche conditions as you would prepare for other avalanche conditions by carrying essential avalanche gear including a beacon, a shovel, and a probe. As you are traveling into an area with avalanche potential, look carefully for recent wet avalanches. Often, if you see one, you?re in an area where conditions are right, and you?re likely to see more. In wet snow conditions, an avalanche may slide down on victims traveling below it, making it seem as if victims are simply in the wrong place at the wrong time. For this reason, it?s even more important to consider terrain features and terrain traps when deciding where to travel. If you are the victim of a wet snow avalanche, you are more likely to die from being crushed in the process of the avalanche, or you will suffocate quickly if you are buried. However, people are caught in wet avalanches less frequently than in dry avalanches. As the victim, follow other avalanche survival advice, and do the following: ?Make sure that you and all others in your group are carrying essential avalanche gear. |
