Advisories 
Advisories Archived Advisories
Advisories Archived Advisories
| MSAC Avalanche Advisory (Archived-01-14-11 09:40:32) |
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 The Mt. Shasta Avalanche Center - US Forest ServiceAvalanche Advisory issued Friday, January 14, 2011 7:00 am By Eric White & Nick Meyers The Bottom Line: Avalanche Danger Rating* for today:   Link to North American Avalanche Danger Scale, revised 2010
*Most avalanche accidents occur during Moderate or Considerable avalanche danger.
Sensitivity to Triggering: Wind slabs near and above treeline will continue to remain sensitive, while wind slabs below treeline may be more stubborn. As temps warm during the day, everything could become touchy. Confidence in today's Forecast: GOOD. We have good confidence in today's weather forecast and we have good field data.
The Details:This Season: Moderate La Nina conditions (cool water temperatures) continue to exist in the equatorial Pacific and climatologists continue to predict strong La Nina conditions during the 2010/2011 winter. This often means cool air temperatures and above normal precipitation for the northern end of California, western Oregon, Washington and southern British Columbia. Check out this link for more information by NWS Meteorologist Brett Lutz: La Nina weather outlook 2010/2011. Our precipitation so far this season is 127% of normal (20.85 inches of water; normal is 16.30 in.) as of 01/14/11. 6-9 ft. of snow will be found between 6000 to 8000 ft.Weather Observations at 5am: We have cloudy skies with calm winds in town and it is currently 37F. On Mt. Shasta: At Sand Flat (6800 ft.) it is 31F at 3am and we have received 1in. of new snow in the last 24 hours with no settlement and 80 inches of snow on the ground. In the Old Ski Bowl at 7600 ft., we received 4 in. of new snow over the last 24 hours and the snow pack settled 1 inch, showing 111 inches of snow on the ground. New snow water content is 15%! Temperatures over the last 24 hours were between 26-40 F and it is currently 40 F. On Gray Butte at 8000 ft. winds in the last 24 hours were from the WNW, averaging 19 mph and gusting to 42 mph. At 6 am, winds gusted to 56 mph from the NNW. Castle Lake: No information available this morning, however in Mumbo Basin, temperatures in the last 24 hours were from 28-40 F. Mt. Eddy: No information available this morning. Nearby at Peterson Flat, 2 inches of new snow is showing and 24 hour temperatures were from 31-38 F. Weather Forecast: We currently sit at the top of a high pressure system, with the low heading mostly to the north of us into Oregon and Washington. The ridge should begin to weaken on Saturday and start to let a bit of precipitation into Northern California Saturday night and into Sunday. Today: Partly to mostly cloudy skies will greet us for today as a few clouds might spill over into Northern California. Temperatures below treeline will be warming gradually into the low to mid 40's with winds variable 5-15mph. Near and above treeline winds will be breezy, 20-30 mph with gusts higher. Expect temps above treeline to be in the upper 30's to 40. Snow levels are high, around 8-9,000 feet. Saturday and Sunday: As the high pressure ridge fades on Saturday, we will begin to see some precipitation start on Saturday night and into Sunday. Not much is expected out of this system, probably around .25-.5 inches of water. Warmer air is accompanied with this system as well and will raise snow levels to 9,000 or higher. Snowpack: (link to encyclopedia of avalanche terms) New snow water content measured 15%, however the snow still skied fairly well yesterday! Winds have been blowing out of the WNW and thus loading S to E aspects near and above treeline. Winds slabs have and will continue to form on these aspects and should be suspect. During the warmest parts of the day, slides will become easier to trigger and touchy. Temperatures were 40 degrees this morning in the Old Ski Bowl and will continue to rise today raising caution. Yesterday, we dug a pit on a WNW aspect at 34 degrees, below treeline. We found moderate failures (RB4), 5 inches down just below the obvious crust layer. A large temperature gradient in the top 20 cm has created a weak layer of near surface facets. With temperatures trending warmer and moderate winds, use caution when traveling near and above treeline! Link to video discussing snow pack on 1/7/11 Link to video showing 1st Rutschblock test 12/31/10 Link to video showing 2nd Rutschblock test 12/31/10 Link to video showing new technique for tests in Maritime snow pack Link to video showing sensitive wind loading 12/30/10 Link to video showing Rutschblock test 12/30/10 Link to video discussing wind on 12/30/10 Link to video showing crown of natural avalanche 12/22/10 Link to video showing Rutschblock test 12/18/10 Link to video discussing snow pack 12/17/2010 Link to video showing Rutschblock results 12/3/2010
Some Important Thoughts: This advisory does not apply to Ski Areas or Highways and is for the Mt. Shasta, Castle Lake and Mt. Eddy back country. Use this information for guidance only. You may find different conditions in the back country and should travel accordingly. This advisory expires at midnight tonight. As always, use safe travel practices: travel with a partner, travel one at a time in suspect areas, go from one island of safety to another, choose safe routes, wear a transceiver, carry a shovel and probe, and know how to use your gear! Pilgrim Creek Snowmobile Park: Ash Creek loop was groomed on Thursday, 1/12. The cat broke down (1/13) and will be out of service for the near future.
Please report weather and snow observations- you could help save a life:· (530)926-9614· Thanks! **Upcoming Events**: Friday, January 14, 7pm - Free Avalanche Awareness presentation at the Mt. Shasta Ranger Station. Brett Lutz, a meteorologist with the National Weather Service, will give a weather and climate outlook for our area as well. This is a great avalanche refresher for those with previous avalanche training and a great introduction to avalanche safety for those new to the back-country. Saturday, January 15, 9am - Free Meet at The Fifth Season (300 N. Mt. Shasta Blvd.). We will have some transceiver (beacon) demos, but if you have your own, bring it! Dress to be outside in the snow (rain). Saturday, January 22, 7pm SNOWBALL! Join us at this great fund raising party hosted by Friends of the Mt. Shasta Avalanche Center (501(c)3). Pizza, music, dancing, raffle items, variety of beverages and tons of fun! Sons of Italy hall in Weed, 155 Clay St. See you there!
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.
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