Spring Time brings us the possibility of corn snow, powder or rain.  Remember it is possible for spring storms to dump impressive amounts of snow and rain.  Most of the avalanche activity associated with these spring storms occurs during or shortly after the storm event.  Timing is critical when playing in avalanche terrain.

Terrain:  Remember most of the terrain that we like to play on is greater than 30 degrees.  Avalanches are possible on anything steeper than 30 degrees, especially wet snow avalanches.  Avoid cornices, rock bands, terrain traps and runout zones of avalanche paths.

Weather:  When there are storms in the spring, they can bring impressive amounts of rain, snow and wind.  This can greatly increase the avalanche danger during and after storms.  Heed the signs: Wind (significant snow transport and depositions), Temperature (rapid/prolonged warming, which in turn weakens the snowpack), and Precipitation (added weight and stress to the current snowpack).

Snowpack:  If snow accumulates, give the snowpack a chance to adjust to the new snow load before you play on or near steep slopes (greater than 30 degrees).  Most direct action avalanches occur within 24-48 hours of recent snowfall.  Watch for obvious signs of snowpack instability such as recent natural avalanche activity, collapsing of the snowpack (often associated with a “whumphing” sound), and shooting cracks. If you see these signs of instability, limit your recreation to lower angle slopes.

If during the warmer parts of the day you see signs that the surface snow is getting warm, such as snowballs rolling down the slope or you find the snow is sloppy enough that you sink in to your boot tops, it would probably be a good idea to play it cool and find another slope to play on or under, or call it a day. If this does happen, avalanches can be triggered.  If the snow only freezes at night, an early start will be imperative.  The snow does soften quickly and will become increasingly unstable throughout the day as it is warmed by solar radiation.  If the snow is soft early in the morning due to a lack of freezing overnight, it is probably a good idea to play another day.

Human Factor: Don’t forget to carry and know how to use avalanche rescue gear. You should NOT be skiing or climbing potential avalanche slopes without having beacons, shovels, and probes.  Only one person in a group should be exposed to potential avalanche danger at a time.  Remember, climbing, skiing, and riding down the edge of slopes is safer than being in the center.  Just because another person is on a slope doesn’t mean that it is safe.  Be an individual!  Make your own decisions.  Heed the signs of instability: rapid warming, “whumphing” noises, shooting cracks, snowing an inch an hour or more, rain, roller balls, wind loading, recent avalanche activity.

The Five Red Flags of Avalanche Danger any time of year include:  1) Recent/current avalanche activity  2) Whumpfing sounds or shooting cracks  3) Recent/current heavy snowfall  4) Strong winds transporting snow  5) Rapid warming or rain on snow.

The final avalanche advisory for the season was 3-30-08.  We will be updating the Climbing Advisory page intermittently as conditions change: www.shastaavalanche.org.  We would like to thank you for your interest in this service.  This includes everyone who sent in avalanche and snowpack observations. These observations are a vital part of the daily avalanche hazard assessment and we really appreciate your input. We hope that we have helped in making your playing time safer.  If you have any suggestions or comments please feel free to contact us:  U.S. Forest Service, Mt. Shasta Avalanche Center, 204 W. Alma St.  Mt. Shasta, CA 96067.  We look forward to sharing more avalanche information with you next season.  In the mean time, enjoy your spring and summer, and be safe out there!    

2007/2008 Season:  Our season started late and has had higher winds than normal above tree line.   Our precipitation is around 73% of normal since September 1, 2007.  January brought several heavy and cold snow storms with mostly dry and warm weather during the first half of February.  We had a strong storm near the end of February with widespread avalanche activity.  March brought very little snow fall.  Snow pack at lower elevations is above normal, just below normal at tree line, and well below normal above tree line due to wind scouring.   Late March snow surveys show the Mt. Shasta snow pack below tree line at around 69-78% of normal.  We are in a moderate “La Nina” climate condition which often means wet and cool weather in our area.  However, expectations for precipitation in the spring of 2008 are uncertain, with equal chances of above or below normal.   Here is what the snow pack looked like at the end of March:

 
2mm rimed stellar and needle snow flakes which fell on 3/28/08  forming the "velvet" 1-2 inch snow surface.
 

1+mm melt/freeze grains which form the bulk of the firm and stable Mt. Shasta snowpack on 3/28/08.

click on Powderbowl photo to enlarge

1/11/08  Casaval Ridge  HS-N-D2-R2  This hard slab released naturally during NW wind loading on a SE aspect at 10,400 ft.  It was 200 ft. wide with a 3-5 ft. crown and travelled 800 ft. vertically.
2/24/08 Widespread Natural Avalanche Activity, including:  Grey Butte, Castle Lake, Castle Crags (multiple), Scott Camp Mnt. above Methodist Camp, Grey Rock/Whalen (multiple).  Many of these were on N and NW aspects with some on W and SW aspects, starting at 6000 - 8000 ft. in elevation.  The largest was on Grey Butte and was 2000 ft. wide.  Conditions leading up to these included:  31 inches of snow with a few hours of 2-4 inches/hour, moderate to strong SE winds occurred, warming temperatures and rising snow levels on 2/24 between 1:00 to 5:00 pm.

       

(L-R) Grey Butte, Castle Lake, Castle Spire.  Click on photos to enlarge.

2/25/08  Carter Summit  SS-AS-D1-R1  A skier triggered a slide after landing on a snow pillow.  This small slide was 50 ft. wide and 6-14 inches deep.  It travelled around 300 ft. to the road where it covered half of the County highway.  The skier easily skied away from the slide.
3/15/08  Crater Lake NP  ?SS-AS-D2 ?  A skier triggered a soft slab 100 ft. wide with a 2 ft. crown.  He travelled with the debris and was buried waist deep.
4/13/08  Castle Lake  A skier triggered a 6 inch deep, 50 foot wide wet slide which carried her down the slope toward the lake.  She was able to get off the debris and ski to safety.  This was due to rapid warming temperatures.
4/22/08  Castle Lake  A snowboarder triggered a small slide in a steep chute.  It carried him 50 feet until he was able to ride off the moving debris to a safe area.  The debris continued down the slope, over a cliff and into the lower part of the chute, stopping on an open slope above the lake.  10-12 inches of new snow had accumulated on a very firm base with poor bonding.

4/22/08 Snowboarder triggered slide, Castle Lake.  Click on photo to enlarge.

Please report natural or human triggered avalanches in Northern California and Southern Oregon to:  MSAC
Avalanche Report Forms

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A BIG thank you to all of you for your help and support this year with all the challenges I faced, especially to the Friends of the Mt. Shasta Avalanche Center and Snow Dog Engineering.  Most importantly, I thank my wife and children for their patience and support with my early mornings, long work days and few breaks.  Be safe out there!  -EW

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Thanks to the Mt. Shasta Ski Park & Ski Patrol, Backcountry Access, Friends of the Mt. Shasta Avalanche Center and the Forest Service for great Beacon Basin days this season at the Ski Park!

    

Some fast, slow and exciting racing with great costumes!  Fun was had by all!  Thanks for another great benefit event!
Join us next season for the 2009 Flying Squirrel!