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Avalanche Advisory for 2014-03-01 07:47:43

  • EXPIRED ON March 2, 2014 @ 7:47 am
    Published on March 1, 2014 @ 7:47 am
  • Issued by Adam Teel - Mt. Shasta Avalanche Center

The avalanche danger is Considerable on upper elevations and Moderate on mid elevations and Low on low elevations today. Our upper elevations could have significant wind slabs today due to slightly stronger than expected winds yesterday mid-morning from the East. The mid-elevation slopes will remain moderate due to some signs of instability within the snow from this week, wind slabs are also possible on some mid-elevation slopes in more exposed areas.

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.

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

Avalanche Problem 1: Wind Slab

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Wind slabs may have formed and gained strength yesterday during the mid-morning when we received higher than expected winds prior to the daytime high temps. Wind ripples were visible above treeline yesterday and we can assume some of this new snow was transported at upper elevations.


 

Avalanche Problem 2: Storm 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 new snow to slide on some of the weaker interfaces within the current pack. These slides pose some hazard due to their inconvenient locations, above rock bands and on convexities.

Recent Observations

The snowpack at mid-elevations was adjusting well yesterday to all the added weight from the last few days but there were still some observed weakness's present within the new snow. Multiple stability tests showed weakness 15-20 cm down from the surface failing between CT 2-4 and ECT3. This failure seemed to be new snow density changes and not threatening and actually gaining strength at mid-elevations  during the day time high at 2:00p.m. on Gray Butte.  33cm from the surface there was another density change that may have had a slight melt/freeze crust which made for a higher quality shear but again the warm temps seemed to be 'healing' this weakness. It was failing consistently at CT8 and had a ECT5 result.

Rapid settlement, roller balls, tree bombs and sun wheels were all observed yesterday at mid-elevation slopes. There seemed to be greenhousing going on during the daytime high. Then the clouds broke and temps dropped for the late afternoon.

The clouds broke yesterday afternoon offering visibilty to the upper mountain and some of the wind affect but no natural activity was noticeable. Wind slabs on the upper elevations could release on the same weak interfaces we have observed at lower elevations but with more energy and consequences. All this new snow could be 'slabbing up' nicely on the upper mountain while on the mid-mountain the weak interfaces are congealing and gaining strength with time and warming temps.

 

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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!

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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 38 F.

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

    Old Ski Bowl - 7,600 feet. Old Ski Bowl has received 3-4 inches in the last 24 hours. There has been approximately 3-4 inches of settlement in the last 24 hours so the total remains at 50 inches. The current temperature is 25F with a low of 25F and a high of 32F.

    Gray Butte - 8,000 feet - The current temperature is 25F. Temps have ranged from a low of 23F to a high 32F.  Winds have averaged 16 mph from the SSE with gusts to 42 mph from the East yesterday at 1100am.

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

    Castle Lake - 5,600 feet, the current temperature is 30F with a low of 30F and a high of 35F. Castle Lake has received 2 inches of new snow and a current snowpack of 8 inches.

    Mt Eddy - 6,500 feet, the current temperature is 27F with a low of 27F and a high of 33F. Mt Eddy has received 3 inches and a current snow depth of 21 inches. Winds have averaged 1 mph with gusts to 10 mph, southerly in nature.

    THIS SEASON: Since September 1st , we have received 8.86 inches of water, normal is 30.17 inches, putting us at 29% of normal. For the year of 2014, Mt Shasta has received 6.04 inches of water with normal being 14.29 inches which puts us at 42% of normal. And lastly, for February we are 81% of normal, receiving 5.83 inches of water, normal is 7.23 inches.

    WEATHER SYNOPSIS:

    Today will remain cloudy with some light snow falling and freezing levels rising through the day but remaining below bunny flat elevation. This means the daytime high temp at bunny  will be above freezing at 34 degrees. Winds out of the SSW 10-20 mph. Tomorrow we can expect 2-4 inches with increasing winds and freezing levels.  Monday looks promising with near 100% chance of precipitation but the freezing levels are still going to be on the rise possibly extending up above bunny flat elevation. Snow and rain can be expected through Monday evening with about 1 inch of  total water expected and temps on the rise. There is some disagreement with the models and forecasts concerning where the freezing levels will be for the upcoming precip, keep your fingers crossed for cold temps.

    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: 4 inches
    Total snow depth: 50 inches

    Two Day Mountain Weather Forecast

    Produced in partnership with the Medford NWS

    For 7000 ft to 9000 ft
      Saturday
    (4 a.m. to 10 p.m.)
    Saturday Night
    (10 p.m. to 4 a.m.)
    Sunday
    (4 a.m. to 10 p.m.)
    Weather Light snow Light snow Snow
    Temperature (°F) 33 27 32
    Wind (mi/hr) South 10-20 mph Southerly 7-14 South 10-20 and gusty
    Precipitation SWE / Snowfall (in) / 1 / 1-3 / 2-4
    For 9000 ft to 11000 ft
      Saturday Saturday Night Sunday
    Weather Light snow Snow likely Snow
    Temperature (°F) 30 25 30
    Wind (mi/hr) South 15-25 mph South 1 South 20-30 and gusty
    Precipitation SWE / Snowfall (in) / 1 / 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.