Avalanche Advisory Archive Pre-2016
Date Issued: | 2013-01-21 |
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Danger: | 2 |
Trend: | 3 |
Probability: | 2 |
Size: | 1 |
Problem: | 0 |
Discussion: | The National Weather Service Forecasts- TODAY...RAIN. HIGHS AROUND 40. EAST WIND 10 TO 20 MPH. TONIGHT...MOSTLY CLOUDY. CHANCE OF RAIN IN THE EVENING. PATCHY TUESDAY...CLOUDY. CHANCE OF RAIN IN THE AFTERNOON. HIGHS AROUND 40. EAST WIND 5 TO 15 MPH. We received nearly an inch of rain overnight. But temperatures were very warm. This only left about one inch of new snow at Mt Roberts Tram Summit elevations. The Eaglecrest UAS site which is at a little higher elevation is showing about 4\". The Mt Juneau Station is along the channel at our highest elevation locally and is only showing a few inches of snow as well. Lower elevation snowpacks are above freezing and may have the ability to move on SUPER steep slopes or if human triggered. Upper elevations have just a little new snow that may or may not be bonding well to the old snow surface. At our uppermost elevations you may see some small windloaded pockets that may be able to be skier triggered. Winds ranged from 15-40 during this event and may have developed some windslabs up high on leewasrd slopes facing W to N. Avalanche danger is MODERATE at this time. With not much precip in the forecast natural avalanches unlikely, potentially destructive avalanches unlikely to come near or reach developed areas. Human triggered avalanches remain possible in isolated pockets near summit and ridgeline and at lower elevations. |
Tip: | Compression Test: I love this test (and its cousin, the stuff block test). It's quick, easy to interpret and works for most kinds of weak layers. Start by isolating a column about the same size as the blade of your shovel, in other words, about one foot by one foot (30 x 30 cm). Be sure to completely isolate the column. Then take the blade of the shovel and lay it flat on top. Finally start tapping progressively harder on the shovel blade until the column fails. Start with ten taps by articulating from your wrist, then ten more taps by articulating from your elbow, then ten more from your shoulder using the full weight of your arm. Don?t push your arm into the snow, but let it fall with its own weight. In this way, the test is somewhat quantifiable. In other words it doesn't depend on ?feel? or the opinion of the tester, but it has a reproducible number which is more or less same for most people and can easily be communicated to others. For instance, it failed on an easy tap from the elbow, or it failed on a moderate tap from the elbow or perhaps a hard tap from the shoulder. Since snow stability is dependent on the size of the trigger required to make it fail, this test is especially easy to interpret. Of course, if you have an unusually light arm or an unusually heavy one, you need to take that into account. If the column breaks when articulating from the wrist = Red light If the column breaks when articulating from the elbow = Yellow light If the column breaks when articulating from the shoulder = Green light |