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Avalanche Advisory for 2016-12-13 06:32:42
- EXPIRED ON December 14, 2016 @ 6:32 amPublished on December 13, 2016 @ 6:32 am
- Issued by Andrew Kiefer - Mt Shasta Avalanche Center
Bottom Line
For today, LOW avalanche danger exists on all aspects and elevations. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features steeper than 35 degrees where a lingering wind slab problem may pose risk to backcountry travelers. Incoming storms will bring new snow and high winds to the advisory area this evening and throughout the rest of the week. Be sure to watch for changing conditions and travel accordingly.
Avalanche Problem 1: Wind Slab
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Character ?
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Aspect/Elevation ?
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Likelihood ?CertainVery LikelyLikelyPossible
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Size ?HistoricVery LargeLargeSmall
Both natural and human triggered wind slab avalanches are unlikely today. Steady northwest winds with strong to extreme gusts have blown for the past several days. All this wind has redistributed the snow from last week unevenly throughout the terrain. In most places near and above treeline, the snow is scoured down to a firm and icy bed surface and hard, wind sculpted snow features exist.
Wind slab development continued beyond our storms from last week. At this point, with widespread scouring, firm and icy snow surfaces, and a rain crust capping the snowpack at lower elevations, the amount of snow available for transport has diminished. Backcountry travelers are most likely to encounter the wind slab problem on isolated terrain features above treeline where firm pockets of loaded snow 1-2ft deep may exist. However, it will be difficult for skiers and riders to trigger wind slab avalanches today. Watch for unstable snow on isolated terrain features steeper than 35 degrees like convex roll overs, unsupported slopes near and above cliff bands, slopes below ridgelines, rock outcrops, and narrow gullies.
Forecast Discussion
Generally safe avalanche conditions exist in the backcountry. Snow surfaces are variable and potentially challenging for skiers, riders, and climbers. Breakable crust is widespread near and below treeline. Firm and icy conditions prevail on steep slopes above treeline and will likely warrant the use of an ice axe and crampons. Use caution in areas of loaded snow as these are the locations where the skiing and riding may be best, and also where wind slab avalanches are most likely today.
Even though the avalanche danger is LOW right now, conditions are looking to change quickly. By tomorrow, and as the week progresses, our forecast area is expecting quite a bit of new snow and high winds. We know all too well this recipe for avalanches, and we will have to closely monitor conditions as they change.
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LOCAL AREA ROAD, NORDIC, AND SNOWMOBILE PARK STATUS:
The Sand Flat cross country ski trails are in good shape still and ready for your cross country skis and snow shoes. 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 time being but will be opening soon! The trails are covered in snow and they are working on getting things going this month. http://www.mtshastanordic.org
The Pilgrim Creek & Deer Mountain Snowmobile Parks are open, however there is no snow at these locations currently. One must drive down the 19 road (Military Pass) for several miles to get to consistent snow before unloading. Private industry is logging out there so watch out for log trucks. 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. 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!
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.
Recent Observations
Moderate northwest winds with strong gusts continued to howl through the upper elevation terrain within the forecast area yesterday. The most noticeable evidence of this has been scouring of windward slopes and exposed terrain features. These steady winds over the past 5 days have created firm, icy snow surface conditions near and above treeline. In lower elevation terrain, a stout rain crust caps the snow surface. Variable and challenging conditions exist for backcountry travelers.
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Have you seen our new, BIG BLUE buttons on our website? Yep, thats them, just up and to your left! You can use those and absolutely should. No more email, no more text, no more messing around! So cool. Please submit your observations by clicking either 'snowpack' or 'avalanche' observation and follow the template. Just a photo? Great! Snowpit profile? Awesome! Video, notes, weather...you name it, there is a place for it. It's simple, easy and fun and extremely useful for us and other users. We also have a drop down menu within the obs template that allows you to submit observations from "out of the forecast area". Heading to Crater Lake or Mt Lassen? Submit some obs! This will help us create the BEST possible avalanche advisory AND provide a great place for peeps to go for checking backcountry conditions. Saddle up!
Weather and Current Conditions
Weather Summary
The last of the dry weather will continue through the morning and early afternoon today as skies become cloudy. Winds will shift to the south as the day progresses averaging 15-20mph, with gusts 30-35mph. By 4pm this afternoon, a significant pattern shift will occur, and our forecast area is expecting unsettled, wet weather through the rest of the week. A warm front lifting northward through the area will bring precipitation beginning late this afternoon. Snow levels will be around 4000ft initially, before rising as high as 7000ft by tomorrow. New snow accumulations of 4-8 inches are expected overnight for areas as low as 6000ft, with steady south winds gusting 35-40mph. Periods of heavy snowfall, mixed with rain at times, will continue through Thursday.
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In Mt Shasta City at 0400, we have a current temperature of 30 F with partly cloudy skies.
On Mt Shasta (South Side) in the last 24 hours...
Old Ski Bowl - 7,600 feet, the current temperature is 26 degrees F. Snow on the ground totals 52 inches with no new snow and little settlement. Temperatures have ranged from 20F to 27F.
Grey Butte - 8,000 feet, the current temperature is 24 degrees F. Temperatures have ranged from 18 F to 25 F. Winds have averaged 10-20 mph out of the west/northwest with gusts to 35 mph.
Mt Eddy Range (West side of Interstate-5)...
Castle Lake - 5,600 feet, the current temperature is 29 degrees F. Temperatures have ranged from 22 F to 34 F. Snow on the ground totals 17 inches with no new snow and little settlement.
Mt Eddy - 6,500 feet, the current temperature is 30 degrees F. Temperatures have ranged from 15 F to 31 F. Snow on the ground measures 22 inches with no new snow and little settlement. Winds have averaged 1-3 mph out of the west/southwest with gusts to 6 mph.
THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 17.50 inches of water, normal is 10.18 inches, putting us at 172% of normal. For the month of December we received 1.03 inches of water, normal is 2.82 inches, putting us at 37% of normal, and finally... for the year of 2016 we've received 50.40 inches of water, normal is 38.18 inches, putting us at 132% of normal.
Always check the weather before you attempt to climb Mt Shasta. Further, monitor the weather as you climb. Becoming caught on the mountain in any type of weather can compromise life and limb. Be prepared.
| 0600 temperature: | 24 |
| Max. temperature in the last 24 hours: | 31 |
| Average wind direction during the last 24 hours: | West/Northwest |
| Average wind speed during the last 24 hours: | 10-20mph mi/hr |
| Maximum wind gust in the last 24 hours: | 35 mi/hr |
| New snowfall in the last 24 hours: | 0 inches |
| Total snow depth: | 28 inches |
Two Day Mountain Weather Forecast
Produced in partnership with the Medford NWS
| For 7000 ft to 9000 ft | |||
|---|---|---|---|
|
Tuesday (4 a.m. to 10 p.m.) |
Tuesday Night (10 p.m. to 4 a.m.) |
Wednesday (4 a.m. to 10 p.m.) |
|
| Weather | snow likely, mainly after 4pm | Snow and Breezy | Rain/Snow and windy |
| Temperature (°F) | 31 | 28 | 37 |
| Wind (mi/hr) | South 15-20 mph | South 20-25 mph | South 30-35mph, gusting 50mph |
| Precipitation SWE / Snowfall (in) | / Trace | / 4-8 | / 3-5 |
| For 9000 ft to 11000 ft | |||
| Tuesday | Tuesday Night | Wednesday | |
| Weather | Windy, slight chance of snow, then snow likely | Snow and windy | Heavy snow and windy |
| Temperature (°F) | 23 | 27 | 28 |
| Wind (mi/hr) | West/Southwest 40-50mph, gusting 60mph | Southwest Trace | West 55-65 mph with gusts 70+ |
| Precipitation SWE / Snowfall (in) | / Trace | / 6-10 | / 15-21 |
