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Avalanche Advisory for 2018-02-21 06:36

  • EXPIRED ON February 22, 2018 @ 6:36 am
    Published on February 21, 2018 @ 6:36 am
  • Issued by Aaron Beverly - Mount Shasta Avalanche Center

Avalanche danger is LOW and NORMAL CAUTION is advised. Firm and icy snow surfaces are widespread and shallow snowpack hazards exist. Minor wind loading has occurred on S-SE-E aspects between 7,500-9,000 ft. 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.

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

Forecast Hotline: (530) 926-9613

Avalanche Problem 1: Normal Caution

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

NORMAL CAUTION means:

  • Watch for isolated slabs.
  • Ski and ride one at a time in avalanche terrain.
  • Don't regroup in run out zones.
  • Basic avalanche rescue skills are essential in avalanche terrain.

Isolated slabs are related to wind and terrain. Look for areas of drifting snow. This will occur on the lee side of ridges, in terrain depressions, on convex terrain features, and in the lee of isolated bands of trees.

Forecast Discussion

Though avalanche danger is low, it may be possible to find small isolated wind slabs near the top of easterly aspects. These don't pose much concern, although triggering even a small slide could knock you off your feet.

An impressive overhanging cornice was observed at the top of Sun Bowl yesterday. Small cornices broke under the weight of a person on Monday so stay clear of their edges in the unlikely event that you are traveling near one.

Wind chills will be well below 0 °F today and tonight. Bring appropriate clothing to keep warm.

Moraines, ridges, and areas above 9000 ft are very icy. An ice axe and crampons are mandatory if you dare venture into this terrain. Self arresting on steep slopes will be difficult if not impossible.

Recent Observations

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Cold temperatures and light to moderate winds have left the snowpack unchanged since Monday. The 2-3 inches of new snow from Sunday's storm remains light and dry and can be found below 9000 ft. Above, new snow has been stripped away by winds. Ridges are icy, exposed, and treacherous.

Some evidence of wind loading was seen on easterly aspects of Sun Bowl. This loading is just below the ridge and does not extend far into runout zones. These runout zones are mostly devoid of new snow and much rock is exposed. No wind slabs were found in lower Sun Bowl. An impressive overhanging cornice could be seen on a isolated eastern aspect.

Below treeline, expect hidden and exposed rocks, chaparral, and forest debris. If you come to ride the 2-3 in of snow in these areas, bring a good attitude and a pair of rock skis. The Upper Sand Flat X-C trail has a nice dosage of new snow that should make classic cross country skiing enjoyable.

Weather and Current Conditions

Weather Summary

Cold temperatures will continue with snow levels remaining near or below town. A skiff of snow is expected today. One to two inches of snow could fall tomorrow. A frontal system moves in Saturday afternoon bringing the possibility of a few more inches of snow through Monday.

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) 19 16 37 28.5 2 N
Sand Flat (6750 ft) 11 11 12 12 18 0 0 0
Ski Bowl (7600 ft) 10.5 7 19.5 12.5 40 0 0.01 0
Gray Butte (8000 ft) 12 7.5 18 11.5 5 18 WSW
Castle Lake (5870 ft) 15 9.5 27 18 8 0 0
Mount Eddy (6509 ft) 16 7.5 20.5 15.5 1 7 WSW 22 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
  Wednesday
(4 a.m. to 10 p.m.) 		Wednesday Night
(10 p.m. to 4 a.m.) 		Thursday
(4 a.m. to 10 p.m.)
Weather A 20 percent chance of snow showers in the morning. Partly sunny. A 30 percent chance of snow. Mostly cloudy. A 50 percent chance of snow. Mostly cloudy.
Temperature (°F) 29 15 25
Wind (mi/hr) SW 5 mi/hr NW 5-10 mi/hr NW 10 mi/hr
Precipitation SWE / Snowfall (in) / 0 / 0 / 1
For 9000 ft to 11000 ft
  Wednesday Wednesday Night Thursday
Weather A 20 percent chance of snow showers in the morning. Wind chill values as low as -7. Windy. Snow showers likely, mainly after 4 a.m. Mostly cloudy. Wind chill values as low as -20. Chance of precipitation is 30%. Snow showers likely. Mostly cloudy. Wind chill values as low as -30. Chance of precipitation is 50%.
Temperature (°F) 8 2 3
Wind (mi/hr) NW 10-15 mi/hr W 0 NW 30 mi/hr
Precipitation SWE / Snowfall (in) / 0 / 0 / 1-2

Season Precipitation for Mount Shasta City

Period Measured (in) Normal (in) Percent of Normal (%)
From Oct 1, 2024 (the wet season) 10.20 27.33 37
Month to Date (since Dec 1, 2024) 0.09 5.06 2
Year to Date (since Jan 1, 2024) 4.37 12.12 36

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.