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Above Treeline / Alpine Conditions

Location Name: 
Old Ski Bowl / Green Butte Ridge / Sargents Ridge
Region: 
Mt. Shasta
Date and time of observation: 
Fri, 12/21/2018 - 1:00pm
Observation made by: 
Forecaster
Red Flags: 
Recent loading by new snow, wind, or rain

Location Map

96067 Mount Shasta , CA
United States
41° 23' 1.5036" N, 122° 12' 19.008" W
California US

Snowpack Observations

Details

A windy day on the mountain. Large plumes of blowing snow streamed off ridgelines, above treeline and in alpine terrain, for a good portion of the day. Most of the snow sublimated off to the east. Some settled into firm wind slabs on low angle terrain concavities and gullies.  Avalanche Gulch (AG) conditions were decent today. AG is a deeper drainage than the Old Ski Bowl drainage, thus a bit more protected from the wind. Old Ski Bowl gets more wind effect on the snow and is generally more scoured than AG. It is also where wind speeds are highest as wind is forced around the mountain during a W-NW wind event. Avy Gulch skiers found decent wind effected powder, dust on supportable crust,  and some icy/firm conditions today. Below treeline hosted some of the best riding of the day. A light and surfy 2-3 inches of new snow sat atop a previously breakable crust. Many above treeline starting zones for avalanches still don't have enough snow for legitimate avalanche concerns and are scoured and icy with rocks exposed. All ridgelines on the south, west and east sides are encrusted in rime and bullet proof ice. North side ridgelines are likely the same. Our stout 12/14 rain crust was observed today, all the way up at 10,000 feet where a test pit was dug. Moderate failures were initiated during column tests (ECTN11@30cm from surface , resistant planar / CT11@30cm-RP) on a weak layer of partially decomposing stellar, needle and plate snow grains at a density change from 4F to 1F. The snow pit was E facing, 9,967 feet, 26 degree slope angle. No avalanches were observed during the day. Numerous test slopes were snowmobiled on without result.

Photos

Weather Observations

Details

Sunny and windy. Temperature was 26.5 degrees F at 10,000 feet, 1300 hours. Blowing snow was sublimating off the mountain. Low clouds and fog sat in the valleys early in the morning and cleared by mid-day, but never completely. Low clouds lingered all day with a few scattered high ones. 

Statistics

Cloud Cover: 
25% of the sky covered by clouds
Blowing Snow: 
Yes
Precipitation: 
None
Accumulation rate: 
None
Air temperature: 
Below Freezing
Air temperature trend: 
Cooling
Wind Speed: 
Strong
Wind Direction: 
West