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Avalanche Advisory for 2016-12-21 06:17:48
- EXPIRED ON December 22, 2016 @ 6:17 amPublished on December 21, 2016 @ 6:17 am
- Issued by Nick Meyers - Shasta-Trinity National Forest
Bottom Line
MODERATE avalanche danger exists on all aspects above treeline. Natural avalanches are unlikely, however human triggered avalanches remain possible above 8,500 feet. Evaluate snow and terrain carefully, and identify features of concern. LOW avalanche danger exists near and below treeline.
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
Transport of snow and wind slab development can occur for several days following the end of a storm. Variable winds have blown and redistributed snow, loading leeward slopes and cross loading alpine terrain features. Old and new wind slabs may remain unstable in isolated areas above treeline on all aspects. Evidence of recent instability has been limited and thus triggering a wind slab is unlikely today, but not impossible, especially for upper elevation terrain.
Travel techniques become sloppy when the avalanche danger is lower. Remember some simple backcountry rules that should be followed every time: ski or ride only one at at time on a slope, make sure your safe zone is SAFE, don't group up in runout zones.
Forecast Discussion
Today is a douldrum day. Overall calm wind and sun should host backcountry skiers and riders. One will encounter a wide range of skiing and snow surface conditions. The past couple days of warmer temperatures softened the snow up considerably below and near treeline and some above treeline slopes. We did not see any loose wet related instability but did observe moist surface layers. Sub-freezing temps this morning has likely created a firm snowpack. Daytime warming should help soften sunny aspects today.
The avalanche concern for today is confined to leeward slopes and cross-loaded terrain features above treeline. These are the specific areas where the wind slab problem may still exist. A couple days of warmer temps has helped consolidate the snowpack and heal sensitive wind slabs. This does not rule out the possibility of a human triggered wind slab, especially at higher elevations on Mt Shasta where temperatures have remained cooler. Signs of avalanche instability will be elusive and backcountry users may find themselves taken by surprise. Continue to use caution in alpine terrain.
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LOCAL AREA ROAD, NORDIC, AND SNOWMOBILE PARK STATUS:
The Sand Flat cross country ski trails are in good shape 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 OPEN for the season! Take advantage of this wonderful venue. Groomed trails accomodate both classic and skate skiing styles. Rentals available. Visit their website for more details. 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
Yesterday, Mother Nature threatened but did not deliver. Clouds, wind and a "wintery mix" of precipitation blew in for a short period. As we've been saying for several days now, variable is the word. Scoured surfaces, wind sculpted snow features, firm and icy slopes, and chalky powder may be encountered in upper elevation terrain. Areas of wind-loaded snow has been recently observed throughout upper elevation terrain on Mount Shasta. Easterly aspects were especially subject to wind loading due to steady westerly winds. That said, no recent signs of instability have been observed below, near or above treeline within the forecast area.
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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
Skies are clearing and today should be very nice with temperatures near normal. Some low level fog may linger in the valleys, but expect sun to shine for most of the day! Winds remain light on the mountain. Tomorrow, a strong frontal system moves into Siskiyou County brining increasing winds and precipitation. By Friday, all areas should see the impacts of the storm. We could see upwards of .75 inches of water by Saturday morning. Snow levels will start near 6 to 7,000 feet and lower as the storm passes. More on this later. For today, get some Vitamin D and exercise!
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In Mt Shasta City at 0500, we have a current temperature of 29 F, two degrees cooler than yesterday at this time.
On Mt Shasta (South Side) in the last 24 hours...
Old Ski Bowl - 7,600 feet, the current temperature is 31 degrees F. Snow on the ground totals 68 inches with 1 inch of settlement. Temperatures have ranged from 30F to 40F.
Grey Butte - 8,000 feet, the current temperature is 31 degrees F. Temperatures have ranged from 30 F to 37 F. Winds have been blowing out of the NW averaging 20 mph, with gusts as high as 49 mph until 1500 when they switched to ENE, 10-20 mph, gusts to 49 mph.
Mt Eddy Range (West side of Interstate-5)...
Castle Lake - 5,600 feet, the current temperature is 30 degrees F. Temperatures have ranged from 28 F to 43 F. Snow on the ground totals 17 inches with little settlement.
Mt Eddy - 6,500 feet, the current temperature is 25 degrees F. Temperatures have ranged from 25 F to 40 F. Snow on the ground measures 24 inches with no new settlement. Winds have averaged 2-3 mph with gusts to 12 mph, SE to SW.
THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 20.25 inches of water, normal is 12.32 inches, putting us at 164% of normal. For the month of December we received 3.78 inches of water, normal is 4.96 inches, putting us at 76% of normal, and finally... for the year of 2016 we've received 53.15 inches of water, normal is 40.32 inches, putting us at 131% 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: | 25 |
| Max. temperature in the last 24 hours: | 41 |
| Average wind direction during the last 24 hours: | NW to ENE |
| Average wind speed during the last 24 hours: | 15-20 mi/hr |
| Maximum wind gust in the last 24 hours: | 40 mi/hr |
| New snowfall in the last 24 hours: | 0 inches |
| Total snow depth: | 33 inches |
Two Day Mountain Weather Forecast
Produced in partnership with the Medford NWS
| For 7000 ft to 9000 ft | |||
|---|---|---|---|
|
Wednesday (4 a.m. to 10 p.m.) |
Wednesday Night (10 p.m. to 4 a.m.) |
Thursday (4 a.m. to 10 p.m.) |
|
| Weather | Sunny | Increasing clouds | A 10 percent chance of snow after 4pm. Partly sunny. |
| Temperature (°F) | 39 | 27 | 38 |
| Wind (mi/hr) | East/Northeast 5-10 mph | East 5-10 mph | Southeast, becoming southwest 10-15 mph |
| Precipitation SWE / Snowfall (in) | / 0 | / 0 | / 0 |
| For 9000 ft to 11000 ft | |||
| Wednesday | Wednesday Night | Thursday | |
| Weather | Sunny | Increasing clouds. Breezy. | A 10 percent chance of snow after 4pm. Partly sunny. Windy. |
| Temperature (°F) | 24 | 24 | 26 |
| Wind (mi/hr) | North/Northeast, becoming East/Southeast in the afternoon 10-15 mph | West/Southwest 0 | West 20-30 mph |
| Precipitation SWE / Snowfall (in) | / 0 | / 0 | / 0 |
