Avalanche Advisory Archive Pre-2016
Date Issued: | 2013-12-23 |
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Danger: | 2 |
Trend: | 2 |
Probability: | 0 |
Size: | 2 |
Problem: | 0 |
Discussion: | The National Weather Service Forecasts- TODAY...RAIN AND SNOW SHOWERS. SNOW ACCUMULATION UP TO 2 INCHES. HIGHS 34 TO 38. SOUTH WIND INCREASING TO 10 TO 20 MPH IN THE MORNING WITH HIGHER GUSTS TO 30 MPH. TONIGHT...NUMEROUS SNOW SHOWERS...MIXING WITH RAIN IN THE EVENING. SNOW ACCUMULATION UP TO 2 INCHES. LOWS 28 TO 32. SOUTH WIND 10 TO 20 MPH DIMINISHING TO 10 MPH IN THE EVENING. TUESDAY...MOSTLY CLOUDY. CHANCE OF SNOW SHOWERS IN THE MORNING... THEN CHANCE OF SNOW IN THE AFTERNOON. HIGHS AROUND 33. LIGHT WINDS BECOMING NORTHEAST 10 MPH IN THE AFTERNOON. Early last week we received 8+\" of light dry snow. At the end of this period we received a bit of water to cap it off with an ice layer. The thickness varied throughout our region but it was mostly present everywhere. Thursday night into Friday it was cold and clear leaving behind a small layer of faceting on this ice crust. These two layers create the potential for problems. The thin ice and facet combo will probably not support the new load all that well. The ice layer is on top of lighter density snow that may collapse at some point. The ice itself may break propagating a fracture across a starting zone. The new snow may not bond all that well to the ice crusts and facet as well. This most recent 36+ hour storm came in quite warm which should help its ability to bond and yet the rate of precipitation may be an issue. We received 48mm of precip in about 36 hours. That is nearly 2\" of snow water equivalent (SWE). This is a fair amount of new load for a short period of time. This 48mm of precip only created 20cm of very high density snow over 20% density at the Mt Roberts Tram Summit Elevations. At higher elevations there may be additional snow but either way the old icy snow surface is feeling the weight of this new load. Winds during the beginning of the storm were quite strong ranging from 13-35mph with gusts well into the 40's. This could have build substantial slabs in the starting zones on the lee aspects to the NNW. This new very wet heavy snow will settle and bond very well over time but it needs time with cooler temperatures for that to happen. The forecasted precip amounts are smaller for today. This should help in the stability trend slightly over time. Temperatures for today are still near the freezing point in our mountain starting zones. Tonight they will start to drop which will help a little with long term stability. Moderate winds are expected to continue. Natural avalanches remain possible during this warm spell with additional load being placed on the snowpack. Slides would not be too large should they occur in the urban environment. Continue to avoid the Flume and Perseverance Trails today. Minimize your exposure to avalanche danger by staying away from this avalanche prone area today as danger remains CONSIDERABLE. Human triggered avalanches remain possible in areas. be cautious in wind loaded areas. Be aware of super steep unsupported slopes. Be cautious of terrain traps. |
Tip: | Special thanks to everyone who came out for Saturdays Avalanche Awareness Course. When your doing your last minute Christmas shopping think of safety items for your ski partners. Do they need a new shovel? A Probe? Do they have a good first aid kit? A bivy sack? A good space blanket? Christmas is a great time to make sure your ski partner had the gear to take care of YOU! |