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Avalanche Forecast for 2019-04-01 06:30

  • EXPIRED ON April 2, 2019 @ 6:30 am
    Published on April 1, 2019 @ 6:30 am
  • Issued by Aaron Beverly - Mount Shasta Avalanche Center

Up to 8 inches of new snow above treeline combined with moderate to strong southerly winds may create wind slabs by tonight. Above freezing temperatures and rain on snow will create the potential for wet loose avalanches near and below treeline. Cornices near and above treeline could begin to break as bonds weaken and weight is added.

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.

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

Avalanche Problem 1: Wind Slab

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Concern for wind slab avalanches will increase tonight with up to 8 inches of snow expected above treeline. Moderate to strong southerly winds may create wind slabs on leeward aspects. As you transition to above treeline elevations where new snow is falling, look for shooting cracks or blocking snow in wind drifted areas of no consequence. This is a sign that wind slabs are forming. Avoid leeward aspects above 35 degrees.

    Avalanche Problem 2: Loose Wet

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    Above freezing temperatures, observed roller balls, ankle to knee high boot penetration, moist snow surfaces, rain-on-snow today, and an underlying crust indicate a potential for loose wet avalanches near and below treeline. Avoid steep slopes where you see roller balls and pinwheels.

    Loose wet avalanches form in new snow or old surface snow that is warming. Warming temperatures, strong solar radiation, or rain-on-snow make the surface snow damp or wet. As the water content increases, the snow becomes unconsolidated. They start at a point and entrain additional snow as they move down hill, and have a characteristic fan-like shape.

    Avalanche Problem 3: Cornice

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    Very large overhanging cornices exist near and above treeline. Warm temperatures and rain will weaken bonds and add weight. Cornices may begin to break. Don't be above or below them. A falling cornice could trigger loose wet avalanches.

    Forecast Discussion

    Predicting loose wet avalanches and breaking cornices is difficult. Timing is everything. We've had above freezing temperatures and we'll have rain today. Similar conditions are expected throughout the week. Keep these problems in mind if traveling near or on steep slopes.

    Recent Observations

    In the last 24 hours, temperatures near 7,000 ft have ranged from 22 to 47 degrees. Temperatures remained above freezing last night. Snow has settled about 3 inches.

    The snowpack yesterday was in a state of transition. Below and near treeline, snow from last week's storms ranged from 6 to 18 inches with wind protected and shady areas holding the most. Snow surfaces were damp to wet, though there were still pockets of dry snow to be found on aspects most protected from the sun. Boot penetration was up to your knees in places. A crust exists at varying depths within the newest snow. Plenty of roller balls were seen on steep slopes.

    Cornices at Castle Lake were large and overhanging, but still mostly intact, though a minor break has occurred above Middle Peak.

    Above treeline, surface snow remains chalky and dry with some wind texture.

    Weather and Current Conditions

    Weather Summary

    In the next 24 hours, 0.69 inches of preciptiable water is expected with 0.44 inches possible tonight. Unfortunately for snow lovers, this will be in the form of rain near and below treeline. Snow levels will decrease slightly from 8,200 ft today to 7,800 ft tonight. Above treeline snow accumulation could be as much as 8 inches.

    Snow levels should drop to 6,600 ft by tomorrow bringing 1-3 inches of snow to near and above treeline elevations.

    Wet weather with high snow levels will persist into next week.

     

    24 Hour Weather Station Data @ 5:00 AM

    Weather Station Temp (°F) Wind (mi/hr) Snow (in) Comments
    Cur Min Max Avg Avg Max Gust Dir Depth New Water Equivalent Settlement
    Mt. Shasta City (3540 ft) 29 27 58 42 1 N
    Sand Flat (6750 ft) 34 22 54 36 135 0 0 4
    Ski Bowl (7600 ft) 34.5 26 46.5 36 180.3 0 0 3.2
    Gray Butte (8000 ft) 33.5 30 45.5 36 9 25 W
    Castle Lake (5870 ft) Station not responding
    Mount Eddy (6509 ft) 35.5 24.5 48 39 2 8 WSW 141.1 0 4
    Ash Creek Bowl (7250 ft)
    Ash Creek Ridge (7895 ft)

    Two Day Mountain Weather Forecast

    Produced in partnership with the Medford NWS

    For 7000 ft to 9000 ft
      Monday Monday Night Tuesday (5 a.m to 5 p.m.)
    Weather Rain. Chance of precipitation is 100%. Rain. Chance of precipitation is 100%. Rain and snow showers. Chance of precipitation is 100%.
    Temperature (°F) 37 32 39
    Wind (mi/hr) South 5-10 South 10-15 South 5-10
    Precipitation SWE / Snowfall (in) / 0 / 0 / 1-3
    For 9000 ft to 11000 ft
      Monday Monday Night Tuesday (5 a.m to 5 p.m.)
    Weather Snow. Blustery. Chance of precipitation is 100%. Snow. The snow could be heavy at times. Windy and gusty. Chance of precipitation is 100%. Snow showers. Breezy. Chance of precipitation is 100%.
    Temperature (°F) 30 22 24
    Wind (mi/hr) Southwest 20-25 Southwest 1-3 Southeast 15-20
    Precipitation SWE / Snowfall (in) / 1-3 / 2-5 / 1-3

    Season Precipitation for Mount Shasta City

    Period Measured (in) Normal (in) Percent of Normal (%)
    From Oct 1, 2018 (the wet season) 35.22 35.46 99
    Month to Date (since Jun 1, 2019) 5.69 5.96 95
    Year to Date (since Jan 1, 2019) 26.81 20.25 132

    Disclaimer

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