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Avalanche Advisory for 2016-12-11 06:55:57
- EXPIRED ON December 12, 2016 @ 6:55 amPublished on December 11, 2016 @ 6:55 am
- Issued by Nick Meyers - Shasta-Trinity National Forest
Bottom Line
Three days of strong west/northwest wind continues today on Mt Shasta. Expect overall MODERATE avalanche danger above treeline and LOW danger below treeline. Near treeline, LOW danger overall with pockets of MODERATE will exist. Aspects N-NE-E-SE-S facing and >37 degrees will be most suspect for triggering small to medium sized wind slabs. Other areas remain scoured and icy making the slide for life possible. Maintain sharp observational skills and safe backcountry travel techniques.
Avalanche Problem 1: Wind Slab
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Character ?
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Aspect/Elevation ?
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Likelihood ?CertainVery LikelyLikelyPossible
Unlikely -
Size ?HistoricVery LargeLargeSmall
While I don't think we'll see large scale wind slab avalanches today, expect isolated pockets of wind deposited snow in the form of small to large wind pillows and riblets. This avalanche problem is confined to mostly above treeline but may be found in some near treeline areas. Much of the snow seems to be sublimating off the mountain, but Mt Shasta hosts a lot of low lying, undulating terrain that can easily pile up wind transported snow. Non-traditional avalanche starting zones come into play with high winds, potentially loading terrain features mid-slope. As of this morning, west/northwest winds have been blowing steady since 12/8. That's three full days of high winds. They'll crescendo this weekend before finally decreasing early next week. Bottom line: that is a long period of time with consistent wind...somewhere within the forecast area, I suspect at least a few areas to host a wind slab or two, small to potentially large. Triggering said wind slabs by human or mechanized vehicle could be stubborn to sensitive. Recent avalanches are one the best clues of instability!
Use your own observational skills to assess where wind slabs, pillows, and wind riblets might exist. Great topography to host this avalanche problem include rock outcrops, narrow couloirs, ridgelines and the upper portions of bowls. Also pay attention to non-traditional mid slope starting zones. Wind slabs should be most suspect on slopes steeper than 37 degrees. Westerly winds will load mostly NE-E-SE slopes, but not limited to. Other wind scoured areas remain icy and smooth, so climbers and skiers beware of the slide for life problem as well. An ice axe and crampons is always a good idea if getting into the steeps on Mt Shasta.
Forecast Discussion
A couple of hold over days for us in Mt Shasta consisting of partly to mostly cloudy skies. Our next best chance of precip remains for Monday night. High winds continue on zee mountain for the remainder of the weekend, west/northwest in nature. The thick rain crust near and below treeline seeks out fresh ACL's and other stretchable and tearable body parts. Scoured, firm and icy sections dot the landscape above treeline. Lighter snow that has filtered down into gullies and depressions could put a smile or two on backcountry riders today. Wind riblets, wind pillows and the occasional wind slab could be encountered as well and leads the charge for our problem of the day. Pay attention to this problem on above treeline, N-NE-E-SE-E facing slopes steeper than 37 degrees where said wind deposits are observed.
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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
Observations were made from Bunny Flat and in the Old Ski Bowl yesterday. The backcountry chatter yesterday was two fold. The first thing we heard was just how horrible the breakable crust was for skiing. The second was, at what elevation does the rain crust cease to exist!? By personal observation, the rain crust is present on Mt Shasta up to about treeline, or 7,700 to 8,000 feet. Above treeline, westerly winds blew for the entire day and a lot of snow transport was visible. One larger natural avalanche was observed below Redbanks, south facing (12,000 ft) in Avalanche Gulch. Another smaller natural came off Casaval Ridge, east facing (9,200 feet). Yesterday was the first time in several days that we've been able to view the mountain and venture above treeline. We are unsure when those avalanches occured, likely within the last couple days. Snow surface conditions vary with areas of scoured, icy old snow, pillows/ribs of wind deposited snow and of course the breakable rain crust. Near and below treeline, a few found a couple hundred feet of nice snow where our recent new snow and some light wind deposit made for good turns. Some low lying areas above treeline, like gullies and depressions, host some decent skiing as well. Rain runnels are visible on the snowpack up to near treeline.
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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
A break in the action for a few days.... not full sun, but perhaps some solar rays at times in the AM hours today. Otherwise, partly to mostly cloudy skies will serve for our layover days. A brief shower is possible here and there, but not likely. Best chance of more snow is set for Monday night. Most notable for the remainder of the weekend is the cranking wind on the mountain. West/Northwest winds continue to blow, 30-40 mph with gusts likely over 50 mph at mid elevations. On the upper mountain, wind speed and gusts are much higher. Extreme winds will persist through the weekend. Cold temperatures have taken over finally with morning temps 15-20 degrees cooler than yesterday morning. Similar high/low temperatures expected for the near future.
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In Mt Shasta City at 0500, we have a current temperature of 23 F with clear skys.
On Mt Shasta (South Side) in the last 24 hours...
Old Ski Bowl - 7,600 feet, the current temperature is 15 degrees F. Snow on the ground totals 53 inches with no new snow and little settlement. Temperatures have ranged from 13F to 31F.
Gray Butte - 8,000 feet, the current temperature is 13 degrees F. Temperatures have ranged from 13 F to 31 F. Winds have averaged 20-25 mph out of the west/northwest with a gust to 49 mph..
Mt Eddy Range (West side of Interstate-5)...
Castle Lake - 5,600 feet, the current temperature is 23 degrees F. Temperatures have ranged from 18 F to 23 F. Snow on the ground totals 18 inches with no new snow and little settlement.
Mt Eddy - 6,500 feet, the current temperature is 15 degrees F. Temperatures have ranged from 15 F to 37 F. Snow on the ground measures 22 inches with no new snow and little settlement. Winds have averaged 2 mph with gusts to 10 mph, southerly in nature.
THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 17.50 inches of water, normal is 9.69 inches, putting us at 180% of normal. For the month of December we received 1.03 inches of water, normal is 2.33 inches, putting us at 44% of normal, and finally... for the year of 2016 we've received 50.40 inches of water, normal is 37.69 inches, putting us at 133% 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: | 14 |
| Max. temperature in the last 24 hours: | 34 |
| Average wind direction during the last 24 hours: | West/Northwest |
| Average wind speed during the last 24 hours: | 10-20 mi/hr |
| Maximum wind gust in the last 24 hours: | 25 mi/hr |
| New snowfall in the last 24 hours: | 0 inches |
| Total snow depth: | 29 inches |
Two Day Mountain Weather Forecast
Produced in partnership with the Medford NWS
| For 7000 ft to 9000 ft | |||
|---|---|---|---|
|
Sunday (4 a.m. to 10 p.m.) |
Sunday Night (10 p.m. to 4 a.m.) |
Monday (4 a.m. to 10 p.m.) |
|
| Weather | Partly sunny. Breezy | A 10 percent chance of snow showers after 4am. Mostly cloudy. Breezy. | A 20 percent chance of snow showers before 10am. Partly sunny. |
| Temperature (°F) | 30 | 18 | 30 |
| Wind (mi/hr) | North, becoming southwest 10-15 mph | West/Northwest 15-20 mph | North/Northwest 15-20 mph |
| Precipitation SWE / Snowfall (in) | / 0 | / 0 | / 0 |
| For 9000 ft to 11000 ft | |||
| Sunday | Sunday Night | Monday | |
| Weather | Partly sunny. Windy. | A 10 percent chance of snow showers after 4am. Mostly cloudy. Windy. | Partly sunny. Windy. |
| Temperature (°F) | 22 | 18 | 20 |
| Wind (mi/hr) | West 30-40 mph with gusts 50+ | West 0 | West 30-40 mph with gusts 50+ |
| Precipitation SWE / Snowfall (in) | / 0 | / 0 | / 0 |
