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Avalanche Advisory for 2014-03-02 08:03:23

  • EXPIRED ON March 3, 2014 @ 8:03 am
    Published on March 2, 2014 @ 8:03 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 likely have significant  wind slabs and cornices. 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 are sure to have developed on the upper mountain and winds will continue with the current and upcoming precip. The storm coming this week is expected to come with strong winds out of the West.


 

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. We have more water weight being added to our snowpack over the next 48 hours. Then another storm coming during the day on Wednesday.

Avalanche Problem 3: Cornice

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There are bound to cornices lurking at upper elevations. The winds have been Southerly with a recent West component so beware on North and Northeast facing ridgelines. The winds have been swirling around our mountain with first hand accounts of coming from all directions. Watch out on any upper elevation ridglines, especially until we can visualize what has formed and where the snow has been deposited.

Recent Observations

Visibility was limited yesterday so upper mountain observations were limited to just over 9000ft. Wind effect was apparent on the firm and partially scoured ridglines. There was a report from Friday afternoon of a cornice release on sergents that ran a couple hundred feet, likely due to the temperature spike that afternoon. Visibility has been mostly obscured and the upper mountain has not been seen since Friday afternoon/evening but wind has definitely been pushing around new snow and we can expect wind slabs, cornices and some natural activity to have taken place up there.

There was a slight crust beneath the new snow yesterday morning from the surface of Wed-Friday's snowfall, it should break down at lower elevations but may be something to keep track of where it extended higher than 8500ft. Hopefully the warm temps will break it down in the next few days. It was about 2.5 inches below the surface at 8000 ft yesterday at 11a.m.

The density changes that have been observed as weak interfaces have been gaining strength and are becoming less of a concern with time and increasing temperatures. This being said they are still present in preserved areas that have didn't feel the brunt of the warming on Friday and when more weight is added they could become a concern in isolated areas. This morning they should be between 12 -24 inches down.

The weather station at Old Ski Bowl has recorded 4 inches of water since February 27th!

 

 

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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 and rain with a current temperature is 44 F.

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

    Old Ski Bowl - 7,600 feet. Old Ski Bowl has received 5 inches in the last 24 hours. There has been approximately 3-4 inches of settlement in the last 24 hours with a total of 52 inches. The current temperature is 29F with a low of 25F and a high of 31F.

    Gray Butte - 8,000 feet - The current temperature is 28F. Temps have ranged from a low of 25F to a high 29F.  Winds have averaged 11 mph from the SW with gusts to 28 mph from the WSW this morning at 100 a.m.

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

    Castle Lake - 5,600 feet, the current temperature is 33F with a low of 30F and a high of 39F. Castle Lake has received no new snow and a current snowpack of 7 inches.

    Mt Eddy - 6,500 feet, the current temperature is 32F with a low of 27F and a high of 35F. Mt Eddy has received 3 inches and a current snow depth of 23 inches. Winds have averaged 1 mph with gusts to 11 mph, southerly in nature.

    THIS SEASON: Since September 1st , we have received 8.86 inches of water, normal is 30.43 inches, putting us at 30% of normal. For the year of 2014, Mt Shasta has received 6.04 inches of water with normal being 14.55 inches which puts us at 42% of normal. And lastly, for February we ended 81% of normal, receiving 5.83 inches of water, normal is 7.23 inches. Since the 27th of Feb we have received over 4 inches of water at the Old Ski Bowl weather station!

    WEATHER SYNOPSIS:

     We can expect snow to keep coming to the upper elevations for the next several days but the temps have increased slightly and will continue to increase pushing our freezing levels up through Tuesday. Snow/rain will be falling through Monday night with winds increasing and coming from the WSW, 1-1.5 inches of water will be added to our current totals. Winds are projected to increase in strength and be ripping from the West Wedenesday afternoon into Thursday with the jetstream directly over our area. Warm, moderate winds, and moist from now through Monday night. Then another round of heavy precip Wednesday into Thursday.

    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: Southwest
    Average wind speed during the last 24 hours: 10 mi/hr
    Maximum wind gust in the last 24 hours: 28 mi/hr
    New snowfall in the last 24 hours: 3 inches
    Total snow depth: 50 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 Snow Snow Snow
    Temperature (°F) 34 28 36
    Wind (mi/hr) Southwest 20-30 and gusty Southwest 20-30 and gusty Southwest 20-35 and gusty
    Precipitation SWE / Snowfall (in) / 2-4 / 3-5 / 3-5
    For 9000 ft to 11000 ft
      Sunday Sunday Night Monday
    Weather snow Snow Snow
    Temperature (°F) 32 25 30
    Wind (mi/hr) Southwest 25-35 and gusty Southwest 3-5 South 20-30 and gusty
    Precipitation SWE / Snowfall (in) / 3-5 / 3-6 / 4-8

    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.