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Avalanche Advisory for 2018-01-30 06:44:10

  • EXPIRED ON January 31, 2018 @ 6:44 am
    Published on January 30, 2018 @ 6:44 am
  • Issued by Andrew Kiefer - Mt Shasta Avalanche Center
  • January 30, 2018 @ 6:44 am

    Advisory Hotline: (530) 926-9613

  • Avalanches are unlikely, and the danger is LOW. Small wind slabs may still exist in isolated areas above 9,000 ft on SE-E-NE aspects. Falling rime ice is a significant concern above treeline on Mount Shasta.

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

Avalanche Problem 1: Wind Slab

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

Natural and human triggered wind slabs are unlikely. Lingering wind slabs may still be found on SE-E-NE aspects above treeline. Avoid obviously wind-loaded unsupported slopes steeper than 35 degrees above 9,000ft on Mount Shasta. Continue to check for the presence of wind slabs by looking for cornices, blowing snow, wind pillows, and hollow sounding snow.

Advisory Discussion

Recent observations indicate wind slabs are becoming unreactive to triggers. Westerly winds have continued to hammer alpine terrain following last week’s storm. No longer are winds productively loading snow, only scouring exposed terrain features and eroding snow surfaces. Generally safe avalanche conditions exist in the backcountry.

Alpine rock features on Mount Shasta are covered with rime ice. As the warming trend continues today and through the week, icefall will be a significant hazard. Be especially careful in Avalanche Gulch below Casaval Ridge, the Trinity Chutes, and Redbanks.

Recent Observations

Skies were grey and cloudy yesterday. For more than 24 hours, temperatures have remained above freezing up to 8,000 ft. West/northwest winds battered the mountain averaging 20-30 mph with gusts over 50 mph at the Grey Butte weather station.

No avalanches or signs of instability have been observed since Saturday. Wind slabs are becoming hard to find. Snow surfaces are variable. Moist and heavy snow exists up to 8,000 ft, while above, breakable melt-freeze crusts, supportable wind crusts, wind-eroded features, and scoured icy surfaces can all be found.

Weather and Current Conditions

Weather Summary

A weak ridge of high pressure will build in the area today. Expect decreasing cloud cover throughout the day, westerly winds, and highs in the mid 40s at 6,000 ft. Tomorrow should be sunny with highs in the 50s. A few systems will move through the Pacific Northwest on Thursday, but northern California should remain dry. The long-term forecasts suggest our area will see above normal temperatures and below normal precipitation.

Season Precipitation for Mount Shasta City

Period Measured Normal Percent of Normal
From Oct 1, 2017 (the wet season) 10.11 21.43 47
Month to Date (since Feb 1, 2018) 4.28 6.22 69
Year to Date (since Jan 1, 2018) 4.28 6.22 69

24 Hour Weather Station Data @ 6:00 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) 32 32 62 43 0 N
Sand Flat (6750 ft) 42 33 43 38 25 0 0 0
Ski Bowl (7600 ft) 39 38 48 43 45 0 0 0
Grey Butte (8000 ft) 39 36 44 41 22 56 WNW
Castle Lake (5870 ft) 43 41 57 47 12 0 1
Mount Eddy (6509 ft) 41 40 50 45 3 16 ESE 26 0 1
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 Tuesday Night Wednesday
Weather Mostly sunny Partly cloudy Mostly sunny
Temperatures 39 deg. F. 26 deg. F. 46 deg. F.
Wind direction West/Northwest Northwest North/Northwest
Wind speed 10-15 mph 10-15 mph 10-15 mph
Expected snowfall 0 in. 0 in. 0 in.
For 9000 ft to 11000 ft
  Tuesday Tuesday Night Wednesday
Weather Mostly sunny and windy Partly cloudy and windy Moslty sunny and windy
Temperatures 30 deg. F. 27 deg. F. 30 deg. F.
Wind direction West West/Northwest Northwest
Wind speed 30-40 mph 25-35 mph 25-35 mph
Expected snowfall 0 in. 0 in. 0 in.

Disclaimer

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