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Avalanche Advisory for 2014-02-28 07:23:13

  • EXPIRED ON March 1, 2014 @ 7:23 am
    Published on February 28, 2014 @ 7:23 am
  • Issued by Adam Teel - Mt. Shasta Avalanche Center

The avalanche danger is Considerable on upper elevations and Moderate on mid and low elevations today. Since Wednesday the mountain has received over three inches of water at 7600ft which translates to 2 to 3 feet of new snow making natural avalanches possible and human triggered avalanches likely on upper elevation avalanche paths.

Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Avalanche Problem 1: Storm Slab

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In the last 48 hours Old ski bowl has recorded over three inches of water in the form of snow. This translates to between 2 and 3 feet of new snow. There were some density changes within that new snow which showed some weakness during compression tests and ski cuts on steep convexities.


 

Avalanche Problem 2: Deep Slab

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There has been a significant amount of weight added our pack quickly and although there is not much of a slab, as of yet, there is potential for all the new snow to slide down to the old surface/new storm snow interface.

Recent Observations

Yesterday there was just under two new  feet of snow observed at bunny flat making for excellent ski conditions especially in the early afternoon. The new snow was well bonded  to the old snow surface and no natural activity was apparent but the visibility was limited and upper elevations could not be seen. The instability was within the new snow where a density change was fracturing and propagating on steep rollovers when intentionally triggered. This same density change failed during compression tests between CT6 and CT10 with a low quality shear.  This denstiy change was about 35 cm from the top of the pack yesterday afternoon but  we have had about .42 inches of water since these observations.

 The old snow surface seemed to bond relatively well with the new snow where observed but remember we had a variety of surface conditions before this storm and we can't assume that interface is strong throughout the area.

 

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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!

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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 with a current temperature is 39 F.

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

    Old Ski Bowl - 7,600 feet. Shasta has received 11inches in the last 24 hours. Our current snow depth total at the Old Ski Bowl is 50 inches. The current temperature is 25F with a low of 23F and a high of 31F.

    Gray Butte - 8,000 feet - The current temperature is 22F. Temps have ranged from a low of 21F to a high 29F.  Winds have averaged 12 mph from the SE with gusts to 28 mph from the ESE this morning at 0400.

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

    Castle Lake - 5,600 feet, the current temperature is 31F with a low of 30F and a high of 36F. Castle Lake has received 6 inches of new snow and a current snowpack of 7 inches.

    Mt Eddy - 6,500 feet, the current temperature is 28F with a low of 28F and a high of 35F. Mt Eddy has received 14 inches and a current snow depth total 17 inches. Winds have averaged 2 mph with gusts to 13mph, southerly in nature.

    THIS SEASON: Since September 1st , we have received 8.72 inches of water, normal is 29.9 inches, putting us at 29% of normal. For the year of 2014, Mt Shasta has received 5.9 inches of water with normal being 14.02 inches which puts us at 42% of normal. And lastly, for February we are 82% of normal, receiving 5.69 inches of water, normal is 6.96 inches.

    WEATHER SYNOPSIS:

    More snow today! Today we should get another few inches with 15-25 MPH winds from the Southeast with strong gusts. Temperature will be in the 30's. A little more snow tonight and Saturday morning then a break with more expected on Sunday and Monday. We're in the track! There is a low pressure moving Northeast through our area bringing us several bands of precip through Sunday morning then we will remain in the jet stream with a front giving us more precip through Tuesday. Snow levels will remain fairly stable at 5000ft.

    CURRENT CONDITIONS at Bunny Flat (6950 ft)
    0600 temperature: 31
    Max. temperature in the last 24 hours: 33
    Average wind direction during the last 24 hours: South
    Average wind speed during the last 24 hours: 7 mi/hr
    Maximum wind gust in the last 24 hours: 28 mi/hr
    New snowfall in the last 24 hours: 12 inches
    Total snow depth: 50 inches

    Two Day Mountain Weather Forecast

    Produced in partnership with the Medford NWS

    For 7000 ft to 9000 ft
      Friday
    (4 a.m. to 10 p.m.)
    Friday Night
    (10 p.m. to 4 a.m.)
    Saturday
    (4 a.m. to 10 p.m.)
    Weather Snow showers Snow likely Snow likely in the morning.
    Temperature (°F) 34 25 36
    Wind (mi/hr) Southeast 15-25 South 7-14 South 7-12
    Precipitation SWE / Snowfall (in) / 3 / 1-3 / 1
    For 9000 ft to 11000 ft
      Friday Friday Night Saturday
    Weather 30 Snow likely Snow likely in the morning
    Temperature (°F) 40 25 30
    Wind (mi/hr) Southeast 25-35mph South 2-4 South 15-25mph
    Precipitation SWE / Snowfall (in) / 2-4 / 1-3 / 1

    Disclaimer

    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.