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Avalanche Advisory for 2017-12-26 07:00:48

  • EXPIRED ON December 27, 2017 @ 7:00 am
    Published on December 26, 2017 @ 7:00 am
  • Issued by Andrew Kiefer - Mt Shasta Avalanche Center
  • December 26, 2017 @ 7:00 am

    Advisory Hotline: (530) 926-9613

  • LOW avalanche danger and normal caution continue. Generally safe avalanche conditions exist. Sparse coverage and firm and icy slopes present significant travel hazards in the backcountry.

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

Avalanche Problem 1: Normal Caution

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

We have high confidence that avalanches are unlikely throughout the advisory area today. Normal caution is advised. The firm, icy, and thin snowpack continues to create backcountry travel hazards. Moving through steep terrain above treeline is challenging and dangerous. Arresting a fall in these conditions would be difficult. Watch out for rocks. Low angle slopes with smooth ground cover offer the best skiing and riding conditions.

-Ski and ride one at a time in avalanche terrain.

-Don’t regroup in run-out zones.

-Avalanche rescue skills are always essential when you travel in avalanche terrain.

Advisory Discussion

October and November storms laid a shallow snowpack at high elevations on Mount Shasta. During Thanksgiving week, it rained up to 10,000ft. This rain event was followed by cold and clear weather which capped the snow surface at 7,000ft and above with a crust, while below, it eliminated any existing snow on the ground. We have had two small storm events this December totaling 10 inches of snow and less than 1 inch of water. Otherwise, high pressure has dominated our weather pattern. Precipitation is well below average, and a large portion of our advisory area is snow free.    

Recent Observations

Yesterday, an outing to the Brewer Creek area delivered sunshine, strong westerly winds, and variable early season riding conditions.

-Very little coverage exists below 6,500ft.

-The height of snow ranges from 30-100cm between 6,500-9,500ft.

-The rain crust that formed on Thanksgiving continues to lock up the lower snowpack. This slick layer is the primary snow surface near and above treeline.

-20-25cm of recycled powder (the December 3rd and December 20th storms) exists at the snow surface on north and east aspects below treeline.

-Snowpack stability is very good throughout the advisory area.

Photo: Scoured and firm conditions on the approach to the Hotlum-Wintun Snowfield.

Weather and Current Conditions

Weather Summary

A high-pressure ridge is bringing dry and stable conditions to the area this morning. Strong temperature inversions have returned. Grey Butte and the Old Ski Bowl weather stations reported steady temperatures near 40 degrees overnight. Expect sunshine and strong westerly winds today. A weak front looks to impact the area tonight and tomorrow morning. This brief disturbance may bring a chance for cloudy skies. Sunshine should return by late morning tomorrow.

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THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 5.83 inches of water, normal is 13.67 inches, putting us at 43% of normal. For the month of December, we have received .29 inches of water, normal is 6.31 inches, which is 5% of normal. And finally for the year of 2017, we received 44.82 inches of water, normal is 41.67 inches, putting us at 108% of normal.

Always check the weather before you attempt to climb Mt Shasta. Further, monitor the weather as you climb. Becoming caught on the mountain in any type of weather can compromise life and limb. Be prepared.

24 Hour Weather Station Data @ 4:00 AM

Weather Station Temp (°F) Wind (mph) Snow (in) Comments
Cur Min Max Avg Avg Max Gust Dir Depth New Water Equivalent Settlement
Mt. Shasta City (3540') 24 24 51 33 1 N
Sand Flat (6750') 41 30 42 38 14 0 0 0
Ski Bowl (7600') 43 30 44 39 19 0 0 0
Grey Butte (8000') 40 29 40 36 17 43 NW
Castle Lake (5870') 43 34 44 39 0 0 0 0
Mount Eddy (6509') 32 28 40 34 2 7 WSW 11 0 0
Ash Creek Bowl (7250') station down
Ash Creek Ridge (7895') station down

Two Day Mountain Weather Forecast

For 7000 ft. to 9000 ft.
  Tuesday Tuesday Night Wednesday
Weather Sunny Partly Cloudy Mostly Sunny
Temperatures 45 deg. F. 32 deg. F. 42 deg. F.
Wind direction West/Northwest Northwest West/Northwest
Wind speed 10-15 mph, Gusting 23 mph 11-14 mph, Gusting 21 mph 11-17 mph, Gusting 26 mph
Expected snowfall 0 in. 0 in. 0 in.
For 9000 ft. to 11000 ft.
  Tuesday Tuesday Night Wednesday
Weather Sunny and Windy Partly Cloudy and Windy Windy. 20% chance of snow before 10am, then mostly sunny.
Temperatures 28 deg. F. 27 deg. F. 28 deg. F.
Wind direction West West West/Northwest
Wind speed 43-48 mph, Gusting 70 mph 45-55 mph, Gusting 80 mph 40-50 mph, Gusting 75 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.