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Avalanche Advisory for 2016-11-14 10:37:48
- EXPIRED ON November 15, 2016 @ 10:37 amPublished on November 14, 2016 @ 10:37 am
- Issued by Jon Dove - Shasta-Trinity National Forest
Bottom Line
The Mt Shasta Avalanche Center is eagerly awaiting the 2016-2017 winter season. We will begin issuing daily avalanche advisories in December. Winter like conditions are currently present on Mt Shasta. This means that there is snow coverage from just below treeline to the summit. This, in turn, means that any new snow will affect the avalanche danger considerably. Any sojourn onto Mt. Shasta will require the proper equipment, thoughtful route finding, and snow pack evaluation. Possible avalanche concerns listed below.
Avalanche Problem 1: Storm Slab
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Character ?
The snow that drapes the mountain's flanks is getting the opportunity to set up as we have seen several days of mild fall temperatures and plenty of sunshine. What this is creating is a possibly firm bed surface for new snow to sit on top of. Any significant amount of new snow that falls has the potential to form storm slabs that will be sitting on top of this older snow surface. Storm slabs are a release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. There are several factors that impact how quickly new snow will bond with the old snow surface. If you choose to travel up on the mountain and enter into avalanche terrain take time to evaluate the terrain and snowpack, especially if there is new snow present. Storm slab problems usually last between a few hours and a few days depending on weather conditions.
You can reduce your risk from storm slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Avalanche Problem 2: Wind Slab
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Character ?
Pay attention for wind slab formations. Wind slabs form both during a storm and during high wind events. They are typically found on leeward sides of ridge tops, moraines, gullies, rock outcroppings, tops of chutes, etc. Snow deposited onto leeward terrain is often smooth and rounded and sometimes sounds hollow and can range from soft to hard. Wind slab problems typically last between a few hours to several days. Wind slabs can develop even on days that it is not snowing, such as the day after a storm when the skies turn blue. So, just like in the winter it is best to give the snowpack ample time to adjust to the new wind load.
You can reduce your risk from wind slabs by waiting a day or two after a storm before venturing into steep terrain. Wind slabs are most dangerous on slopes with exposure to terrain traps such as gullies, cliff bands, abrupt transitions, trees and rocks in the run out zone, etc.
Forecast Discussion
THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season) through April 17th, we have received 37.61 inches of water, normal is 37.16 inches, putting us at 101% of normal. For the month of April we've received 0.88 inches of water, normal is 1.70 inches, putting us at 51% of normal, and finally... for the year of 2016 we've received 28.12 inches of water, normal is 21.95 inches, putting us at 101% of normal.
Recent Observations
SPRING STATEMENT 2016:
During spring weather, the avalanche danger is generally lowest during the night and early morning hours when the surface snow refreezes due to heat loss to the surrounding atmosphere. During the day, sun effects and warm air temperatures can rapidly melt and weaken surface snow layers and produce increasing avalanche danger during the late morning and afternoon. Loose wet avalanche activity generally starts on east and southeast facing slopes during the afternoon. Therefore the safest time to cross potential avalanche terrain is during early morning hours before the surface snow begins to warm and weaken.
This daily melt-freeze cycle is strongly affected by any cloud cover during the night since clouds at night limit cooling and may prevent re-freezing. Lack of a thorough surface re-freeze may allow melt water to affect and weaken progressively deeper layers in the snow cover. Snowpack weakening is maximized when warm days are followed by warm overnight temperatures and overcast skies. Backcountry travelers should exercise particular caution under these conditions as it may increase the wet snow avalanche potential.
Backcountry travelers and climbers should also be aware that spring storms might quickly produce avalanche conditions. Although precipitation may fall as rain at lower elevations, substantial new snow may be deposited at higher elevations. This new snow may form a poor bond with an old crusted snow surface. Rapid rises in temperature following the storm due to intense solar effects may quickly warm and weaken any recent snow, which may need little or no disturbance to slide. While subsequent loose wet slides may start small, they can entrain more snow as they descend and could trigger larger wet slab slides as well.
Be aware of hazards overhead regarding cornices and rime ice formations that were formed in late winter and spring. Cornices become more unstable and likely to fail during warm weather. Also, cornice fall may trigger loose wet or wet slab avalanches on slopes below.
Rain may also increase the likelihood of avalanches. Rain falling on an already wet snowpack causes water to quickly percolate through the snowpack and weaken progressively deeper snow layers. If the water encounters a crust or ice lens it may flow along this layer and lubricate it, making avalanches increasingly likely within the snow above.
No matter what the season, backcountry travelers and climbers should avoid slopes of questionable snowpack stability. Remember that small avalanches may be dangerous.
Finally, we extend a giant thank you to all who have helped support the Mt Shasta Avalanche Center. Your observations, donations, feedback and general support are very much appreciated. The climbing rangers will continue to update the website for climbing conditions throughout the spring. Thanks for the great season and we will see you back here next winter!
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The Five Red Flags of Avalanche Danger any time of year include: 1) Recent/current avalanche activity 2) Whumphing sounds or shooting cracks 3) Recent/current heavy snowfall 4) Strong winds transporting snow 5) Rapid warming or rain on snow.
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LOCAL AREA ROAD, NORDIC, AND SNOWMOBILE PARK STATUS:
The Sand Flat cross country ski trails are still covered in snow. A little bit of fresh snow has them in better shape currently, though they have been a little crusty before this last storm. Tree wells are beginning to show. These are backcountry routes marked with blue diamonds on trees. Trails are not groomed. Snow shoers, please blaze a parallel trail to cross country skiers staying out of the skin track. These trails can be accessed via the Everett Memorial Highway. Thank you, and enjoy!
The Mt. Shasta Nordic Center is CLOSED for the season. http://www.mtshastanordic.org
The Pilgrim Creek & Deer Mountain Snowmobile Parks are open, however there is currently no snow at these locations. One had to drive down the 19 road (Military Pass) to get to consistent snow before unloading. Head to our "Education" tab on our website and find the snowmobile section for trail information, grooming status, and other sledder resources.
The Castle Lake Road is OPEN. The Everett Memorial Highway is OPEN to Bunny Flat. The gate at Bunny Flat is open from July 1st to November 1st, regardless of snow conditions. The Castle Lake and Everett Hwy are plowed year round to the trailheads. The roads are not always first priority, so your dawn patrol powder mission might be ceased if the plow has not made it up yet. Siskiyou County does a great job keeping the roads clear. Be respectful of the plow drivers if you encounter them. If you get to Bunny Flat before or during when the plow is there, please park on the uphill, LEFT side of the parking lot as you drive in. This is uphill and lookers right of the bathrooms. Thank You!
Weather and Current Conditions
Weather Summary
Please check our 'Weather' tab at the top of the page for our weather station information, NWS discussions and spot/recreational forecasts.
ALWAYS check the weather before you attempt to climb or recreate on Mt. Shasta. Continue to monitor the weather as you climb. Becoming caught on the mountain during any type of weather can comporomise life and limb. Please be prepared!
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| New snowfall in the last 24 hours: | -- inches |
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Two Day Mountain Weather Forecast
Produced in partnership with the Medford NWS
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