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Avalanche Advisory for 2018-12-04 06:00

  • EXPIRED ON December 5, 2018 @ 6:00 am
    Published on December 4, 2018 @ 6:00 am
  • Issued by Aaron Beverly - Mount Shasta Avalanche Center

Avalanche danger is LOW at all elevations. LOW avalanche danger does not mean no avalanche danger. Continue to look for wind slabs in isolated areas on leeward slopes greater than 35 degrees. Be wary of obstacles beneath the snowpack.

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.

Forecast Hotline: (530) 926-9613

Avalanche Problem 1: Wind Slab

  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Wind slabs may be encountered in isolated areas. Look for these primarily on SE-E-NE aspects but mountain winds are variable and will be changing to the S and E today so be wary of them wherever there is evidence of wind loading.

Evaluate snow and terrain carefully. Avoid wind slabs by traveling in windward areas where snow surfaces have been eroded. Avoid slopes greater than 35 degrees where wind loading has occurred. Evaluate conditions as you travel in safe terrain by looking for signs of the wind slab problem:

  • Smooth rounded wind pillows
  • Hollow sounding snow
  • Harder snow atop softer snow
  • Shooting cracks

Forecast Discussion

LOW avalanche danger does not mean NO avalanche danger. Watch for unstable snow in isolated areas or in extreme terrain.

Recent Observations

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A series of winter storms beginning on Thanksgiving (November 22, 2018) has brought 50 inches of snow above 7000 ft. Current height of snow (HN) at the Old Ski Bowl weather station is 38.6 inches.

Cold temperatures have prevailed over the last few days keeping snow light and dry though expect most unsheltered areas above treeline to be wind affected.

A stability test at 9300 ft yesterday on a SW aspect reveals some weakness in the snowpack below a crust 65 cm down from the snow surface. ECPT14 ↓ 75 cm.

No natural or human triggered avalanches have been observed in the last 2 days.

Ground obstacles are now mostly protected by the snowpack, but some still exist.

Weather and Current Conditions

Weather Summary

A low pressure system off the coast will swing some moisture into the area today and tomorrow. Generous point forecasts are calling for up to 5 inches by tomorrow afternoon, but don't expect much out of this one. Snow levels will rise to 3900 ft by tonight. More precipitation is lining up for the weekend with the bulk coming on Sunday.

24 Hour Weather Station Data @ 4:00 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) 33 17 42 30.5 1 N
Sand Flat (6750 ft) 25 9 27 20 30 0 0 1
Ski Bowl (7600 ft) 21 15 26.5 22 38.6 0 0 3
Gray Butte (8000 ft) 20 13 23.5 18.5 8 25 ESE
Castle Lake (5870 ft) station down
Mount Eddy (6509 ft) 23 12 26 21 1 7 SW 32.2 0.4 2.5
Ash Creek Bowl (7250 ft) station down
Ash Creek Ridge (7895 ft) station down

Two Day Mountain Weather Forecast

Produced in partnership with the Medford NWS

For 7000 ft to 9000 ft
  Tuesday
(4 a.m. to 10 p.m.) 		Tuesday Night
(10 p.m. to 4 a.m.) 		Wednesday
(4 a.m. to 10 p.m.)
Weather A 30 percent chance of snow showers, mainly after 10 a.m. Mostly cloudy. A 30 percent chance of snow showers. Cloudy. A 40 percent chance of snow showers, mainly before 4 p.m. Cloudy.
Temperature (°F) 31 26 31
Wind (mi/hr) E 7 E 5 E 4
Precipitation SWE / Snowfall (in) / < 0.5 / < 0.5 / < 0.5
For 9000 ft to 11000 ft
  Tuesday Tuesday Night Wednesday
Weather A 30 percent chance of snow showers. Mostly cloudy. A 40 percent chance of snow showers. Cloudy. A 50 percent chance of snow showers, mainly before 4 p.m. Cloudy.
Temperature (°F) 23 21 21
Wind (mi/hr) S 20 S < 0.5 SE 12
Precipitation SWE / Snowfall (in) / < 0.5 / < 0.5 / < 0.5

Season Precipitation for Mount Shasta City

Period Measured (in) Normal (in) Percent of Normal (%)
From Oct 1, 2024 (the wet season) 5.07 8.03 63
Month to Date (since Dec 1, 2024) 0.34 0.67 51
Year to Date (since Jan 1, 2024) 20.35 36.03 56

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.