Avalanche Advisory for 2014-12-14 07:02:14

The storm that began on Wednesday the 10th of December gave the Mt Shasta area a large dollup of new snow that came in mostly "right side up". That is, heavier snow on the bottom and lighter snow on the top. As much as 4 feet of snow fell in 48 hours and was accompanied with moderate, southwest winds. Wind slabs and deep slabs are the avalanche problems of most concern, however that concern is decreasing and snowpack stability improving.

Yesterday, folks from all over the Northstate came to Bunny Flat to recreate. Recreationalists of all types fanned up onto the mountain with their tools of choice. I had most concern for snowmobilers, however by the end of the day, we saw no major slides and/or incidents. One natural surface slough was noted off of Sargents Ridge and several skier triggered sloughs off of Gray Butte, though nobody was caught. Perfect visibility allowed for good viewing of upper elevations. No large slabs were recorded. Observations from several locals also noted no signs of instability.

My travels took me to many aspects on and around the Gray Butte area yesterday. Stability tests resulted in only a sore hand from smacking CT and ECT tests. I was hard pressed to get any failure or note any weak layer with tests and pit profiles. That being said, I still am slightly suspect of isolated areas, high on the mountain (>9,000 ft). While wind and storm slabs will be stubborn to trigger, though if triggered by snowmobiler and/or multiple people on a slope, the consequences would likely be a large and destructive slide. Continue to use caution in extreme terrain, bowls, and wind loaded ridgelines on the upper mountain.

Well-developed surface hoar was seen in low lying areas as well as ridgelines, all over Gray Butte. While beautiful and fun to ski now, if the surface hoar remains intact as the new storm arrives tonight, this could create our next weak layer in the coming days. Take note!

Photo: Meyers

Backcountry skiers on 12/12/14 came across some impressive debris of a large natural avalanche (HS-N-D3-R3) that slid down Avalanche Gulch proper and ran past the Horse Camp (Sierra Club) cabin. The avalanche likely occured on 12/11/14. The avalanche came down through Avalanche Gulch proper, and not the "climbers gully". Thus, the starting zone was likely the Sargents Ridge, Thumb, Redbanks area. This slide is a good reminder of the potential for large avalanches on Mt Shasta during heavy winter storms. Slides like this can easily extend into runout zones on relatively flat terrain...ground that one might travel on and think they are not in avalanche terrain. Always know what slopes are above you and travel with caution even when below treeline. You may be in a runout zone. 

Slide path from Avalanche Gulch slide. Impressive! Thanks Robin! Photo: Robin Kohn

Faint crown line seen off of Green Butte/Sargents Ridge. Photo: Shane Rathbun

Report your observations to the MSAC! A photo, a few words... send them in! (nimeyers@fs.fed.us or 530-926-9614)

Castle Lake area still has very little snow. The road is also closed due to road damage from flooding.

Mt Eddy area is hosting about a 18" of snow. I have not been up into that area yet and have received no reports.

Sand Flat Winter Trails: OPEN

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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.  Avoid cornices, rock bands, terrain traps and runout zones of avalanche paths.

Weather:  Most of our areas avalanche danger will occur 24-48 hours after a storm. We still can see persistent weak layers from time to time and we always will be sure to let you know about that!  Heed the basic signs: Wind (significant snow transport and depositions), Temperature (rain/snow/rain/snow, which in turn weakens the snowpack), and Precipitation (Snow or rain add 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.

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.