Due to staffing cuts, advisories are only updated on Friday, Saturday and Sunday

Avalanche Advisory for Friday, January 16, 2009 at 6:30 am  

By Eric White   

The Bottom Line:

Avalanche Danger Rating* for today:                                                                24 Hour Trend:

	Extreme	Widespread natural or human triggered avalanches are certain
	High	Natural and human triggered avalanches are likely.
	Considerable	Natural avalanches are possible.  Human triggered avalanches are probable.
	Moderate	Natural avalanches are unlikely.  Human triggered avalanches are possible.
X	Low	Natural avalanches are very unlikely.  Human triggered avalanches are unlikely.

&	Avalanche Danger is expected to Increase
"	Avalanche Danger is expected to continue at this rating
(	Avalanche Danger is expected to Decrease

 

 

 

           

*Most accidents occur during Moderate to Considerable ratings

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

Size and Character:  Medium wind slabs above 12,000 ft.

Sensitivity to Triggering:  Very stubborn; difficult to trigger

Level of Uncertainty in forecast:   

 

Low

Moderate

High

 

 

 

The next Avalanche Advisory will be posted:  Saturday, January 17, 2009

The Details:

This Season:  Following a very dry summer, we had significant snowfall above treeline in early November with 5-7 feet.  Warm and dry weather followed, creating a smooth and firm melt freeze snow pack of 2-3 feet above 8500ft.  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 snowpack continues with around 1-2 feet in most areas.  Precipitation this season is 59% of normal (on this date last year, 1/16/08 we had 104% precipitation).  The climate forecast is trending toward 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 clear skies with light NE winds in town this morning.  It is currently 27F in Mt. Shasta City with a continued temperature inversion (colder air in valleys, warmer air in mountains).  Mt. Shasta -  We are measuring 22 inches of snow on the ground at 6700 ft. with no new snow over the last week.  (Last year on 1/18/08 we had 66 inches on the ground)  Very little settlement has occurred in the snow pack occurred over the last week.  Temperatures have remained unseasonably warm over the last 2 weeks.  Temperatures over the last 24 hours ranged between 32F yesterday morning to 52F yesterday afternoon at 6700 ft. and it is currently a toasty 33F this morning.  Winds this morning are around 15 mph from the SE below tree line.  At 10,000 ft. winds are estimated at 10-15 mph from the NE.  On the upper mountain winds are estimated at 25 mph from the NNE this morning.  Castle/Mt. Eddy -  Mt. Eddy received no new snow and little settlement in the last 24 hours.  We are measuring 14 inches on the ground at 7200 ft.  The temperature on Mt. Eddy over the last 24 hours has ranged between 46F to a roasting 64F and is currently 47F.   Near Castle Lake we are measuring 14 inches of snow on the ground with no new snow over the last 24 hours and little settlement.  Temperatures near Castle Lake have been between 27-62Fover the last 24 hours.  The current temperature is 37F.  

 

Weather Forecast:  The warm and dry conditions have created spring like weather with some areas hitting record high temperatures.  Currently the whole west coast is dry with storms moving into SW Alaska.  This trend will continue with some cooling starting Sunday and into next week.  A storm will break through the high pressure at the end of next week (1/21-24), but it looks like the high pressure will rebuild after that.  One hope is for the Madden-Julian to strengthen and possibly bring warm and moist conditions in 2 weeks.  For today, expect clear skies with temperatures below tree line warming to the mid 50’s with some areas hitting the low 60’s.  Winds below tree line will continue from the E at 10-15 mph.  Above tree line, temperatures will warm to the low 40’s with winds from the ENE at 20-25 mph.

     

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.  However, in north facing aspects, facets 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 temperatures have helped to lessen the sensitivity of wind slabs high on the mountain.  While conditions have improved for mountaineers on Mt. Shasta, remember, many rocks and boulders continue to protrude through the snow and will be dangerous for long falls/slides.  Climbers should practice ice axe self arrest.

 

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 backcountry 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 snowpack. 

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New Website:  While currently under construction and testing, a new website is in the works for the Mt. Shasta Avalanche Center.  Most of the work is being done by a single individual in our Friends group.  A big thanks to Chad!

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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!

 

 Archived Avalanche Advisories Courtesy of CSAC.org