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Avalanche Advisory for 2014-02-14 07:30:21

  • EXPIRED ON February 15, 2014 @ 7:30 am
    Published on February 14, 2014 @ 7:30 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest

Currently, the avalanche danger is LOW for all aspects and elevations. Be careful of shallow buried objects!
Rockfall is still a hazard on Mt. Shasta until we receive significant snow. Climbing is not recommended on select routes. Be sure to check the climbing advisory if you still choose to climb.


Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Avalanche Problem 1: Wet Slab

  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Very Likely
  • Size ?
    Very Large

A very wet layer of snow sandwiched between two crust layers about 23 to 42 cm deep in the snowpack is trapping water seeping into the snow. This layer is saturated and greasy and proved to be the weakest layer in the snowpack yesterday. More rain on snow and snow at times could increase the instability of this layer.

All aspects and wide open slopes >35 degrees with smooth bed surfaces should be most suspect. Rain on snow will add weight to snowpack.


Recent Observations

We've had a mixed bag of rain and snow over the week with fluctuating snow levels. All elevations below Bunny Flat (6,950 ft) received mostly rain with some mixed snow and very wet.

I dug several pits yesterday in the Old Ski Bowl, and numerous aspects on Gray Butte. On average, Mt Shasta has received 17-20cm of new snow over the work week. Snow fell down to as low as 5,400 feet over the week, 2-4cm and wet. The most noticeable snow accumulation occured 7,000 feet and above however.

View pit profile below. This profile is representative of much of what I saw yesterday in the snow above 7,000 feet. We have about 18-23cm of new snow on top of a 1cm crust. Bump down 18cm, and you will find another 1cm crust. Below this crust and taking us to the ground is older, 1 finger hardness snow. What is happening right now, due to rain on snow and fluctuating snow levels, is the rain/moisture is seeping down through the top layer of new snow, hitting the first crust layer and slowly percolating into the snow layer in between the two crusts. This percolating water has completely saturated this mid 18cm of snow and is quite greasy in nature. It proved to be the weakest layer in the snowpack. I received test scores as follows: CT16/Q3 @ 32cm, CT12/Q3 @ 25cm, ECTN11@32. 

We still have a shallow snowpack with good anchoring terrain (rocks, bushes, trees, forest debris) and this is likely the reason we are not seeing any slides on this wet layer. However, I'm not ruling it out that we could see a wet slide or two triggered in the coming days. It's important to remember that rain adds only weight to the snowpack. As we receive more rain on snow and snow at times in the coming days, this could stress the snowpack to failure. Areas that are wide open, steeper than 35 degrees with several feet of snow on it could be suspect.



As always when our snowpack is shallow, watch out for objects that can cause injury near the surface of the snow.


Some trailheads are still accessible by 4 x 4 vehicle. Be cautious of any overnight trips on the mountain with snow involved. Storms can easily dump large amounts of snow to the area and make it difficult to drive off the mountain! While Northgate, Brewer Ck and Clear Ck trailheads are officially closed, the bathrooms are still open with packout bags inside, and one can still access the Mt Shasta Wilderness. However, your summit pass and wilderness permits must be purchased at McCloud or Mt Shasta Ranger Stations. NO DOGS are allowed in the Mt Shasta Wilderness OR Sierra Club Property. Thanks!


Terrain:  Remember most of the terrain that we like to play on is greater than 30 degrees.  Avalanches are possible on anything steeper than 30 degrees.  Avoid cornices, rock bands, terrain traps and runout zones of avalanche paths.

Weather:  Most of our areas avalanche danger will occur 24-48 hours after a storm. We still can see persistent weak layers from time to time and we always will be sure to let you know about that!  Heed the basic signs: Wind (significant snow transport and depositions), Temperature (rain/snow/rain/snow, which in turn weakens the snowpack), and Precipitation (Snow or rain add weight and stress to the current snowpack).

SnowpackIf snow accumulates, give the snowpack a chance to adjust to the new snow load before you play on or near steep slopes (greater than 30 degrees).  Most direct action avalanches occur within 24-48 hours of recent snowfall.  Watch for obvious signs of snowpack instability such as recent natural avalanche activity, collapsing of the snowpack (often associated with a “whumphing” sound), and shooting cracks. If you see these signs of instability, limit your recreation to lower angle slopes.

Human Factor: Don’t forget to carry and know how to use avalanche rescue gear. You should NOT be skiing or climbing potential avalanche slopes without having beacons, shovels, and probes.  Only one person in a group should be exposed to potential avalanche danger at a time.  Remember, climbing, skiing, and riding down the edge of slopes is safer than being in the center.  Just because another person is on a slope doesn’t mean that it is safe.  Be an individual!  Make your own decisions.  Heed the signs of instability: rapid warming, “whumphing” noises, shooting cracks, snowing an inch an hour or more, rain, roller balls, wind loading, recent avalanche activity.



    Weather and Current Conditions

    Weather Summary

    In Mt Shasta City this morning at 0500, we have overcast skies and light rain falling with a down right balmy current temperature of 50 F.

    On Mt Shasta (South Side) in the last 24 hours...

    Old Ski Bowl - 7,600 feet, we've had 1-2 inches new snow over the last 24 hours and 7-8 inches new snow over the week, above 7,200 feet. Rain on snow at times has occured up to 8,000 feet.. Our current snow depth total at the Old Ski Bowl is 2 feet. The Old Ski Bowl snow depth sensor still needs more snow to begin to measure accurately. However, I recently measured the snow at the weather station location and recorded an average of 2'. The current temperature is 34F with a low of 31F and a high of 35F.

    Gray Butte - 8,000 feet - The current temperature is 33F. Temps have ranged from a low of 31F to a high 34F.  Winds have been westerly in nature, averaging 18mph with gusts to 42mph.

    Castle Lake and Mt Eddy (West side of I-5)... 

    Castle Lake - 5,600 feet, the current temperature is 39F with a low of 35F and a high of 44F. Castle Lake has received no new snow with a current snowpack of 1-3 inches. Mostly rain on snow has occured over the week at Castle Lake.

    Mt Eddy - 6,500 feet, the current temperature is 37F with a low of 34F and a high of 40F. Mt Eddy has no new snow and a current snow depth total of 6-8 inches with 2-3 inches settlement (rain on snow). Winds have averaged 2 mph with gusts to 9 mph, south in nature.

    THIS SEASON: Since September 1st (the wet season), we have received 5.71 inches of water, normal is 26.08 inches, putting us at 21% of normal. For the year of 2014, Mt Shasta has received 2.89 inches of water with normal being 10.20 inches which puts us at 28% of normal. And lastly, for February we are 85% of normal, receiving 2.68 inches of water, normal is 3.14 inches.

    Mt Shasta finished off 2013 with exactly 10.00 inches of water, normal is 43.21", putting us at 23% of normal.

    December 2012 had more precipitation than the entire 2013 calendar year (10.43"). WOW!


    A chain of moisture extends from Hawaii northeast across the Pacific and hits Southern Oregon and Northern California today and the coming weekend. This will bring plenty of water, but not cold temperatures, at least in the beginning. Forecasts show 1.91 inches of water expected through Saturday night. Snow levels look to reach their highest, about 8,000 feet this morning, will begin to drop Saturday evening, and potentially reach Shasta City limits by early Sunday. We should see a short break in the weather Sunday and part of the day Monday, but be ready for another wet and colder blast beginning Monday night and Tuesday.

    Today, expect mixed rain and snow. Snow levels will fluctuate and could be as high as 8,300 feet with little accumulation. West winds will be cranking, 40-50mph with gusts higher. Rain on snow is a guarantee and wet, sloppy conditions inevitable!



    CURRENT CONDITIONS at Bunny Flat (6950 ft)
    0600 temperature: 34
    Max. temperature in the last 24 hours: 35
    Average wind direction during the last 24 hours: West
    Average wind speed during the last 24 hours: 18 mi/hr
    Maximum wind gust in the last 24 hours: 42 mi/hr
    New snowfall in the last 24 hours: 1-2 inches
    Total snow depth: 24" inches

    Two Day Mountain Weather Forecast

    Produced in partnership with the Medford NWS

    For 7000 ft to 9000 ft
    (4 a.m. to 10 p.m.)
    Friday Night
    (10 p.m. to 4 a.m.)
    (4 a.m. to 10 p.m.)
    Weather Rain Rain Rain in AM, then rain and snow
    Temperature (°F) 42 36 40, falling to 36
    Wind (mi/hr) South/Southwest 20-30mph South 10-15mph West/southwest 25-35mph
    Precipitation SWE / Snowfall (in) / .5-.75" water / .5-.75" water / 1-2
    For 9000 ft to 11000 ft
      Friday Friday Night Saturday
    Weather Snow Snow Snow
    Temperature (°F) 34 29 34
    Wind (mi/hr) West/Southwest 40-50mph with gusts higher Southwest 2-4 South/southwest 45-55mph with gusts higher
    Precipitation SWE / Snowfall (in) / 2-4 / 1-2 / 2-4


    This advisory does not apply to Ski Areas or Highways and is for the Mt. Shasta, Castle Lake and Mt. Eddy back country. Use this information for guidance only. You may find different conditions in the back country and should travel accordingly. This advisory expires on midnight of the date it was posted unless otherwise noted.