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Avalanche Forecast for 2018-12-28 06:09

  • EXPIRED ON December 29, 2018 @ 6:09 am
    Published on December 28, 2018 @ 6:09 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest

LOW avalanche danger exists for all aspects and elevations. Natural and human triggered avalanches of consequence are unlikely. Watch for small avalanches in isolated areas or extreme terrain. Northerly winds will continue to blow near and above treeline today.

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

Strong northerly winds will continue near and above treeline. Existing wind slabs remain difficult to trigger. Much of the snow available for transport as been stripped away. Watch for small, new wind slabs in isolated areas, extreme terrain, and/or small pockets in protected, steep couloirs. 

Signs of a wind slab problem:

  • Blowing snow
  • Cornices
  • Wind pillows
  • Shooting cracks 
  • Hollow sounding snow

Forecast Discussion

We're feeling a bit like a broken record these days, or in other words, message fatigue. If you've followed the forecast this season, the wind slab avalanche problem and northerly winds have been talked about... a lot. This makes sense as Mount Shasta sticks up thousands of feet higher than any other terrain in the area. Despite our repetitious messages, keep your situational awareness up out there.

Recent Observations

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A cold and windy day on the east side of the forecast area yesterday, despite clear skies and sunshine. Northerly wind continued to batter near and above treeline terrain. The entire east aspect of Mount Shasta looked mostly scoured from afar, judging by the salt and pepper morain tops and exposed faces. Leeward gullies facing E-SE held some snow. A large, wide crown line (D2-3) looked barely visible on the Hotlum/Wintun snowfield. Our position was near Ash Creek Butte. The large avalanche path down the east side of Ash Creek Butte held old avalanche debris in the runout zone. A wide spread, thin sun crust seems to dominate most snow surfaces up to 8,000 feet out there. Overall, a right side up snowpack with good stability was observed with 70cm of snow above the 12/13 rain crust. Total height of snow averaged 170cm. Large, thick wind slabs were observed in on many leeward, SW-S-SE aspects near and above treeline, though triggering them would be very difficult. Some minor cracking along slab edges was possible, but not notable. High winds have swept most available snow for transport down into lower lying areas. 

Weather and Current Conditions

Weather Summary

Benign weather is in store for the foreseable future. Valleys will host morning fog. The mountains will be windy and mostly clear with slightly warmer temperatures. Saturday night brings a slight chance of light precipitation, nothing to get too excited about. Long term, next Thursday another front moves in.

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) 25 24 41 33.5 4 N
Sand Flat (6750 ft) 16 14 26 21 41 0 0 0
Ski Bowl (7600 ft) 29 17 33.5 25 49 0 0 2
Gray Butte (8000 ft) 18.5 15.5 30 23 22 61 NNE
Castle Lake (5870 ft) station down
Mount Eddy (6509 ft) 23.5 18 23.5 20 3 15 SE 41 0 0
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
  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 Mostly sunny, breezy Partly cloudy Mostly sunny, slight chance of rain and snow after 4pm
Temperature (°F) 32 28 39
Wind (mi/hr) North 10-15 North 5-10 North 5-10
Precipitation SWE / Snowfall (in) / 0 / 0 / 0
For 9000 ft to 11000 ft
  Friday Friday Night Saturday
Weather Mostly sunny, windy Partly cloudy, windy Mostly sunny, slight chance of snow after 4pm, windy
Temperature (°F) 24 24 28
Wind (mi/hr) North 35-40 North 0 Northwest 20-25
Precipitation SWE / Snowfall (in) / 0 / 0 / 0

Season Precipitation for Mount Shasta City

Period Measured (in) Normal (in) Percent of Normal (%)
From Oct 1, 2023 (the wet season) 8.41 14.19 59
Month to Date (since Apr 1, 2024) 3.68 6.83 54
Year to Date (since Jan 1, 2024) 23.69 42.19 56

Disclaimer

This forecast 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 forecast expires on midnight of the date it was posted unless otherwise noted.