| 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 Sunday, January 18, 2009 at 6:30 am Happy MLKJ Holiday weekend! By Eric White 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. |
| Moderate | locally unsafe conditions. Evaluate the snow and terrain carefully. Use good travel habits to minimize risk. | | X | 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: Low avalanche danger; generally stable snow with isolated areas of instability Primary Concern: Old wind slabs above 12,000 ft. on E and S aspects Secondary Concern: Size and Character: Medium wind slabs above 12,000 ft. Sensitivity to Triggering: Very stubborn; difficult to trigger
Level of Uncertainty in today's Forecast: Trend over the next several days: We are expecting little change in the snow stability through the middle of the week. | The next Avalanche Advisory will be posted: Friday, 01/23/09 |
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. Shallow and below normal snow pack continues with around 1-2 feet in most areas. Precipitation so far this season is 58% of normal. The forecast trend continues to favor La Nina conditions to continue 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 clear skies and light NNE winds in town this morning. It is currently 27F in Mt. Shasta City with a temperature inversion continuing (cold air settles in valleys; warm air rises to mountains). Mt. Shasta: We are measuring 21 inches of snow on the ground at 6700 ft. with no new snow over the last 24 hours and little settlement in the snow pack. Previous years on this date: 66 in. 1/18/08, 56 in. 1/18/07, 132 in. 1/17/06. Unseasonably warm temperatures continue, ranging between 32F yesterday morning to 53F yesterday afternoon at 6700 ft. and it is currently 34F. Winds this morning are light from the SE below tree line. At 10,000 ft. winds are estimated at 15 mph from the SE. On the upper mountain winds are estimated at 20-25 mph from the SE this morning. Castle/Mt. Eddy: Mt. Eddy received no new snow and little settlement in the last 24 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 41F to 68F and is currently 43F this morning. Near Castle Lake we are measuring 13 inches of snow on the ground with no new snow over the last 24 hours and 1 inch of settlement. Temperatures near Castle Lake have been between 27-64F over the last 24 hours and currently it is 28F. Weather Forecast: Our current warm and dry conditions have created spring like weather with some areas hitting record high temperatures. The strong high pressure will begin changing mid week with cooling and hopefully some snow later in the week. Today: Sunny skies will continue with temperatures below tree line warming to the upper 40's on Mt. Shasta and upper 50's near Castle Lake/Mt. Eddy. Winds below tree line will remain light from the SE. Above tree line, temperatures will warm to the upper 30's to 40F with winds continuing from the SE at 15 mph, increasing early tomorrow morning to 25-30 mph from the SE. Extended: Slight cooling into the week with temperatures returning to near normal on Wednesday. A storm will most likely go south of our area mid week, bringing only clouds to Mt. Shasta. However, a cold front will arrive on Friday evening and possibly bring us a little bit of powder by Saturday morning - a present for the SnowBall event Saturday night! Winds will continue from the SE during the first part of the week, then move to the SSW mid week. Winds will move the NW Thursday and then back to the SSWon Friday. Models are currently showing light to moderate wind speeds this week. Snow Pack: The last 2 weeks of warm temperatures have created melt-freeze surface conditions with open, south facing areas providing spring, corn snow conditions. As temperatures cool this week, firm conditions will keep skiers closer to tree line and lower elevations. On north facing aspects, we are finding facets which have become well developed below the surface melt/freeze crust. As these continue to grow, they will become an important weak layer if we ever receive more snow and should be monitored. The warm temperatuers have helped to lessen the sensitivity of wind slabs high on the mountain. While conditions have imporved for mountaineers on Mt. Shasta, remember, many rocks and boulders continue to protrude through the snow and will be dangerous for long falls/sl;ides. Climbers should be able to self arrest with an ice axe immediately when slipping/falling. below tree line on easterly snow surface below tree line yesterday. Surface hoar is my current research project: 
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. Due to unseasonably warm temperatures, these are currently hard to find. 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:
Avalanche Awareness, Wednesday, January 21, 7pm, Turtle Bay Exploration Park: Join us for this 1 hour presentation on avalanches and traveling safely in the back country during winter and spring.  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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