| The Mt. Shasta Avalanche Center - US Forest Service Due to staffing cuts, Advisories will only be posted on Friday, Saturday & Sunday from December to April Avalanche Advisory for Friday, January 23, 2009 at 7:00 am By Eric White Our new website is provided by Friends of the Mt. Shasta Avalanche Center, and specifically Chad - Thanks!!! The Bottom Line: Avalanche Danger Rating* for today: | | EXTREME | Avoid all avalanche terrain. Travel only on gentle slopes well away from avalanche paths and run-out areas. | | | High | Widespread dangerous conditions. Exposure to avalanche terrain is not recommended. Extensive experience assessing snow and terrain is required for safe travel. | | | Considerable | Variable conditions and uncertainty require conservative decision making. Careful route selection and good travel habits are required. | | X | Moderate | locally unsafe conditions. Evaluate the snow and terrain carefully. Use good travel habits to minimize risk. |
| Low | Generally safe conditions. Watch for unstable snow on isolated terrain features. | *Most avalanche accidents occur during Moderate or Considerable avalanche danger. 24 hour trend | | Avalanche danger is expected to increase. | | ⇒ | Avalanche danger is expected to continue at this rating | |
| Avalanche danger is expected to decrease. | Where: Moderate avalanche danger above 7000 ft. Primary Concern: storm snow slabs above tree line on many aspects Secondary Concern: wet slides at lower elevations Size and Character: Small and shallow slabs Sensitivity to Triggering: medium to lower sensitivity
Level of Uncertainty in today's Forecast:
| The next Avalanche Advisory will be posted: Saturday, 01/24/09 |
The Details: This Season: Following a very dry summer, we had significant snowfall above tree line in early November with 5-7 feet. Warm and dry weather followed, creating a smooth and firm melt/freeze snow pack 2-3 feet deep above 8500 ft. in elevation. Unusually cold weather in the second week of December created weak layers. A warm front at the end of December created a rain crust. Most of January has been warm and dry, with light rain/snow during the 3rd week. Shallow and below normal snow pack continues with around 1-2 feet in most areas. Precipitation so far this season is 55% of normal. The forecast trend continues to favor La Nina conditions which is good for most of the Pacific NW, but can leave us with windy and drier conditions similar to last season. Weather Observations: We have mostly cloudy skies and calm winds in town this morning. It is currently 40F in Mt. Shasta City. Mt. Shasta: We are measuring 21 inches of snow on the ground at 6700 ft. with 1-2 inches of new snow over the last 36 hours and 1 inch of settlement in the snow pack. Temperatures over the last 24 hours have ranged between 32F last night to 36F yesterday afternoon at 6700 ft. and it is currently 32F. On Grey Butte at 8000 ft. it is currently 29F with winds from 7-14 mph from the NE. On the upper mountain winds are estimated at 10-15 mph from the SW this morning. Castle/Mt. Eddy: Mt. Eddy received 1 inch of new snow in the last 36 hours with 14 inches of snow measured on the ground at 7200 ft. The temperatures on Mt. Eddy over the last 24 hours have ranged between 31F to 36F and is currently 32F this morning. Near Castle Lake we are measuring 11 inches of snow on the ground with a trace of new snow over the last 24 hours. Temperatures near Castle Lake have been between 33-40F over the last 24 hours and currently it is 33F. Weather Forecast: Areas in the central and southern Sierra received a lot more precipitation during the last 24 hours than up here in the north State. Low pressure remains off of the central and southern California coast and will continue to provide precipitation south of our area. We may see some light precipitation over the next 24 hours, with the best chance tonight and early tomorrow morning with 2-3 inches possible above 6000 ft. Unsettled weather will continue into the weekend with temperatures cooling Sunday and snow levels dropping closer to town. Below tree line today we will see temperatures rising to the upper 30's and winds remaining light from the ESE, then moving to the SSE tonight and SSW tomorrow morning at 5-10mph. Above tree line today, temperatures will be in the mid to upper 20's and close to freezing at tree line. Winds near tree line will remain fairly light from the SSE today at 10 mph and move to the SSW tomorrow morning. Snow Pack: Our shallow snow pack went through extended periods of melt/freeze over the last few weeks on southerly aspects, strengthening the snow. Northerly aspects did see near surface faceting, creating a weak layer under the surface crust. The recent storm has been light and relatively warm with snow bonding well to the crust at mid elevations. Warm and wet conditions at lower elevations have created a fairly uniform thin snow pack. Rain has been light enough to not create unstable conditions, but wet slides could be possible at lower elevations on very steep slopes with smooth ground surfaces (Castle Crags). Around 2-3 inches of snow accumulated above tree line and with light winds, the coverage is fairly even. Some small and shallow slabs have formed in a few areas on NE aspects at higher elevations. The best snow conditions today will most likely be near and above tree line on the mountain, being observant for shallow obstacles. Although rain has destroyed surface hoar, it is my current research project and here are a few photos from this season: 
Large surface hoar crystals formed 12/16-18 in many areas below treeline. photo 12/17/08, Castle Lake 
Large surface hoar crystals formed 12/29-31/08 at Castle Lake, growing on a rain crust.  
2-6 mm surface hoar crystals formed again below tree line on 1/2-4/09 sitting on a 3 inch layer of powder over a concrete crust.  
Chandelier surface hoar found in pockets near Castle Creek, 1/15/09. These grew from a rain crust and ended in striated cups. 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! Please report weather and snow observations: (530)926-9614 Thanks! Pilgrim Creek Snowmobile Park: No grooming has taken place this season due to thin snow pack.
Upcoming Events:
 7th Annual SnowBall, Saturday, January 24, 6pm - ? This great event is the major fund raising project of the volunteer, non-profit, Friends of the Mt. Shasta Avalanche Center who support our work. Dinner, music, dancing, beer, wine, soda and tons of raffle/silent auction items. See you there! Avalanche Awareness Presentation, Friday, February 6, 6pm: This is a great FREE intro to avalanches or a great refresher to those who have taken classes before. In this 1 hour talk, we will discuss the factors which lead to avalanche formation and some of the observations and skills you can use to identify instability in the snow pack. Join us at the Mt. Shasta City Library, 515 East Alma St., Mt. Shasta, next to Sisson Middle School.
Avalanche Transceiver Clinic, Saturday, February 7, 9am: Bring your transceiver or use a demo to practice your rescue skills. Dress warm and meet us at The Fifth Season, 303 N. Mt. Shasta Blvd., at 9 am. FREE!
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.
Please report weather and snow observations: (530)926-9614 Thanks!
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