Category Archives: Bulletin

Springtime 2012

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Springtime 2012

AVALANCHE PROBLEM

list of avalanche problems
DANGER
 
LOW with frozen snow becoming HIGH with wet snow
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger increases during the day with the heat of the sun and decreases with overnight cooling. Expect to easily trigger moist and wet new snow avalanches.
 
TRAVEL ADVISORY: Avoid avalanche terrain during the heat of the day. Time your activities accordingly.
 
There is fantastic snow cover. Conditions are generally safe. Danger is confined to new windslabs in the upper elevation and avalanche terrain with moist, wet and rotten snow. It is still winter on the north aspects up top and cold snow avalanches are possible. 
 
Until the crust melts during the day, it holds the snowpack together. The snowpack gets stronger with successive freeze/thaw cycles. Even isothermal snow gains strength over time. However, remember that large wet snow avalanches are expected during the spring shed and that even small avalanches can have serious consequences.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
SNOW:  
 
VALDEZ
 THOMPSON PASS
 24 Hour 
~
~
May
~
34"
Season Total
438"
692"
 Base
 ~
107"
   
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

Monday, May 14, 2012

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Monday, May 14, 2012
Forecast valid until updated

AVALANCHE PROBLEM

list of avalanche problems
TODAY'S DANGER
 
MODERATE
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger will increase to CONSIDERABLE, even HIGH when the skies clear and the 27 inches of new snow which has accumulated since last Wednesday is exposed to the heat of the sun.
 
WEATHER: The last storm of the winter storm is tapering off. Expect sunny skies Tuesday through the remainder of the week.
 
TRAVEL ADVISORY: Avoid avalanche terrain. In the upper elevations there are new windslabs knee deep to thigh deep. The snowpack is rotten below 2500 feet elevation and higher on south aspects.
 
More than 18 inches of snowfall has accumulated above the elevation of Thompson Pass. There is a foot of heavy wet new snow on the ground at the Pass.
  
AVALANCHE DISCUSSION: On Saturday numerous avalanches ran at Milepost 40 and 41 with one to the valley bottom. New snow avalanches are expected in the upper elevations and will gouge into any rotten old snow beneath it.
 
Avalanches will run this week when the skies clear. Expect a widespread cycle of new snow point release avalanches to size 2.5. The new snow avalanches which gouge into rotten old snow will increase in mass considerably. Human triggered windslab avalanches remain possible in the upper elevations today and are likely this week.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
 24 Hour 
~
3"
May
~
34"
Season Total
438"
690"
 Base
 ~
113"
   
 
CONFIDENCE: Fair - limited visibility, few observations.
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

Sunday, May 13, 2012

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Sunday, May 13, 2012
Forecast valid until updated

AVALANCHE PROBLEM

list of avalanche problems
TODAY'S DANGER
 
CONSIDERABLE
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger will remain CONSIDERABLE until the weather clears and the new snow stabilizes.
 
WEATHER: Winter storm tapering off over the next two days in the upper elevations with continued periods of rainfall in the lower elevations. Clearing Tuesday. Lovely thereafter.
 
TRAVEL ADVISORY: Avoid avalanche terrain. In the upper elevations there are new windslabs knee deep to thigh deep. The snowpack is rotten below 2500 feet elevation and higher on south aspects. Expect moist and wet snow avalanches at the mid and low elevations. Expect windslab avalanches in the upper elevations.
  
AVALANCHE DISCUSSION: Numerous avalanches have run at Milepost 40 and 41 with one to the valley bottom. New snow avalanches are expected in the upper elevations and will gouge into any rotten old snow beneath it.
 
More than 18 inches of snowfall has accumulated above the elevation of Thompson Pass. There is more than a foot of new snow on the ground at the Pass with 1.75 inches of snow water equivalent. In addition to the snowfall, there has also been an inch of rainfall for a total of 2.75 inches of water at the Pass. In Valdez, 1.63 inches of rainfall has accumulated since the storm started.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
 24 Hour 
~
5"
May
~
32"
Season Total
438"
688"
 Base
 ~
114"
   
 
CONFIDENCE: Fair - limited visibility, few observations.
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

Saturday, May 12, 2012

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Saturday, May 12, 2012
Forecast valid until updated

AVALANCHE PROBLEM

list of avalanche problems
TODAY'S DANGER
 
CONSIDERABLE
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger will remain CONSIDERABLE in the upper elevations until the weather clears and the new snow stabilizes.
 
WEATHER: Winter storm in the upper elevations. Rainfall in the lower elevations. Clearing later today. Lovely thereafter.
 
TRAVEL ADVISORY: New windslabs to thigh deep.
  
AVALANCHE DISCUSSION: New snow avalanches are expected in the upper elevations and will gouge into any rotten old snow beneath it.
 
More than 18 inches of snowfall is expected to have accumulated above the elevation of Thompson Pass. There is a foot of new snow on the ground at the Pass with 1.75 inches of snow water equivalent. In addition to the snowfall, there has also been an inch of rainfall for a total of 2.75 inches of water at the Pass. In Valdez, 1.63 inches of rainfall has accumulated since the storm started.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
 24 Hour 
~
5"
May
~
28"
Season Total
438"
684"
 Base
 ~
114"
   
 
CONFIDENCE: Fair - no visibility, few observations.
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

May 7, 2012

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Spring 2012

Although daily avalanche bulletins have finished for the season, there will be updates until next winter.

Avalanche danger still exists. There is still 100" on the snowstake at Thompson Pass, which is plenty of snow to pose avalanche hazard to backcountry travelers.

When you do get on the snow, please continue to share you what you see on the observations page.

During the spring thaw, the danger varies between generally LOW when the snow is frozen to CONSIDERABLE or HIGH when the snow warms up and becomes wet and rotten.

TRAVEL ADVISORY: Spring is not a time to drop your guard. The snow and avalanche conditions are variable; extremely dependent on temperature and aspect to sun and wind. When they do go, spring avalanches can go BIG - look at your route with consequences in mind.
 
Good planning and preparation will pay off. In spring, timing is everything - watch the temperature trend and figure out how that is affecting the snow. If you are shedding layers, the mountains will too.
 
Be aware that it is still winter-like in upper elevations. Expect areas of dry snow that might not bond to layers beneath. If the snow is dry, the wind will move it - watch for pockets of windload.
 
Other springtime concerns:
  • Weak/dropping cornices
  • Weak snow bridges over crevasses and bergschrunds
  • Rockfall
  • Open water - rivers, creeks, and lakes
  • Hungry bears?
AVALANCHE DISCUSSION:
Watch for
1) Wet loose avalanches gouging into thawed old snow, increasing mass and destructive potential
2) Full thickness releases to ground, such as the one May 2nd off Mt Snowslide at Milepost 16 (top end of Keystone Canyon). Also, watch the enormous wrinkles above town. These are glide avalanches in the making.
3) Dry avalanches that come out of the alpine and entrain wet snow in the lowers
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
May Snow
2"
7"
Season Total
438"
663"
 Base
17'
99"
   
 
2011-2012 Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

Monday, May 6, 2012

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Monday, May 6, 2012

Thank you for making the fourth annual Avalanche Center end of season party a fantastic success.
AVALANCHE PROBLEM

list of avalanche problems
TODAY'S DANGER
 
MODERATE
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger remains generally LOW. However, there are two exceptions. The danger is MODERATE where the new snow has drifted into windslab. There is CONSIDERABLE danger where the snowpack is rotten.
 
WEATHER: Over the weekend expect better weather in the mornings followed with a greater chance of precipitation after noon.
 
TRAVEL ADVISORY: Expect areas in the upper elevations where Tuesday's and Wednesday's new snow has drifted into windslabs up to a foot thick.
   
AVALANCHE DISCUSSION: Watch for:
1) new snow avalanches gouging into thawed old snow increasing mass and,
2) full thickness releases of the snowpack to ground, such as the one Wednesday off Mt Snowslide at Milepost 16 at the top end of Keystone Canyon. See also the enormous wrinkles above town.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
 24 Hour 
0"
0"
May
2"
5"
Season Total
439"
661"
 Base
2-5'
102"
   
Snow load April 30th measured by Valdez NWS is 57.2 pounds/square foot. 
 
CONFIDENCE: Good
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

 

Wednesday, May 2, 2012

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Wednesday, May 2, 2012
Forecast valid 8:00 am May 2nd to 8:00 am May 3rd

Support your Avalanche Center. Eat, drink and be merry. Annual party tomorrow.

AVALANCHE PROBLEM

list of avalanche problems
TODAY'S DANGER
 
MODERATE
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger remains generally LOW. However, there are two exceptions. The danger is CONSIDERABLE where the new snow has drifted into windslab. The danger is CONSIDERABLE where the snowpack is rotten.
 
WEATHER: Remaining cloudy as a series of weak systems through the weekend continue to deposit a few more inches of snow in the upper elevations.
 
TRAVEL ADVISORY: Expect flat light conditions and new snow drifts to knee deep.
   
AVALANCHE DISCUSSION: Loose point release avalanches of new snow will be observed as the new snow is exposed to daytime warming. Watch for the new snow avalanches gouging into the old snow that has thawed which will increase the mass of the avalanches. Although less likely during the next few days, there remains the possibility of full thickness releases of the snowpack to ground.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
 24 Hour 
2"
3"
May
2"
3"
Season Total
439"
659"
 Base
27"
102"
   
Snow load April 30th measured by Valdez NWS is 57.2 pounds/square foot. 
 
CONFIDENCE: Good
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

Tuesday, May 1, 2012

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Tuesday, May 1, 2012
Forecast valid 8:00 am May 1st to 8:00 am May 2nd

Support your Avalanche Center. Fill your belly at the annual fund raiser party Thursday

AVALANCHE PROBLEM

list of avalanche problems
TODAY'S DANGER
 
MODERATE
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger remains steady.
The danger is LOW where the snowpack remains frozen throughout the day.
The danger raises to CONSIDERABLE, even HIGH, where the snowpack becomes rotten during the heat of the day.
 
WEATHER: Cloudy. Weak system approaching overnight which may bring a few inches to the upper elevations.
 
TRAVEL ADVISORY: Of all the snow types available now (cold, dry, new, old, corn and rotten) the snow that is the least fun and least safe is the rotten snow. Expect rotten snow in the lower elevations as well as at all elevations where the snowpack has thawed over the past month. Rotten snow in avalanche terrain is dangerous until it becomes corn snow. There is a bit of new snow in the upper elevations See Snow Observations page.
 
Snow-bridges covering glacier crevasses and bergschrunds are weakening and sagging. Glacier travel requires rescue and safe travel skills and equipment. Beware of failing cornices. Stay well away from their edge and limit your exposure beneath. Cornice fall is a large load which has the potential to trigger an avalanche.
  
AVALANCHE DISCUSSION: Wet loose avalanches remain expected in steep terrain. Wet slab avalanches also remain possible, especially as the day warms up. What will happen as the huge glide crack opens up above town to the right of two previous releases? So far the snowpack has wrinkled and folded as it slowly moves downslope. Will it release? When?
 
The avalanche conditions of concern remain:
1) point releases gouging old snow increasing mass and,
2) where the full thickness of the snowpack releases to ground.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
 24 Hour 
0"
0"
May
0"
0"
Season Total
437.6"
656"
 Base
27"
102"
   
Snow load April 30th measured by Valdez NWS is 57.2 pounds/square foot. 
 
CONFIDENCE: Good
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

Monday, April 30, 2012

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Monday, April 30, 2012
Forecast valid 8:00 am April 30th to 8:00 am May 1st

Support your Avalanche Center and fill your belly at the annual fund raiser May 3rd

AVALANCHE PROBLEM

list of avalanche problems
TODAY'S DANGER
 
MODERATE
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger remains steady.
The danger is LOW where the snowpack remains frozen throughout the day.
The danger raises to CONSIDERABLE, even HIGH, where the snowpack stays rotten overnight or becomes rotten during the day.
 
WEATHER: Cloudy with chance of showers - generally better than forecast.
 
TRAVEL ADVISORY: Of all the snow types available now (cold, dry, new, old, corn and rotten) the snow that is the least fun and least safe is the rotten snow. Expect rotten snow in the lower elevations and slopes at all elevations warmed over the past month. Rotten snow in avalanche terrain is dangerous until it becomes corn snow (and even corn snow takes some management). There is a bit of new snow in the upper elevations.
 
Snow-bridges covering glacier crevasses and bergschrunds are losing strength and sagging. If you choose to travel on glaciers, you need rescue and safe travel skills and gear. Beware of failing cornices. Stay well away from edge and limit your exposure beneath. Cornice fall is a large load and has the potential to trigger an avalanche.
  
AVALANCHE DISCUSSION: Wet loose avalanches remain expected in steep terrain. Wet slab avalanches also remain possible, especially as the day warms up.
 
Expect to see point releases of this weekend's new snow on south aspects and to find drifts of soft windslab in the upper elevation.
 
The avalanche conditions of concern are:
1) point releases gougig old snow increasing mass and,
2) where the full thickness of the snowpack releases to ground.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
 24 Hour 
0"
0"
April
5.1"
16"
Season Total
437.6"
656"
 Base
38"
100"
   
Snow load April 23rd measured by Valdez NWS is 89.2 pounds/square foot. 
 
CONFIDENCE: Good
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet

Sunday, April 29, 2012

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Sunday, April 29, 2012
Forecast valid 8:00 am April 29th to 8:00 am April 30th

Support your Avalanche Center and fill your belly at the annual fund raiser May 3rd

AVALANCHE PROBLEM

list of avalanche problems
TODAY'S DANGER
 
MODERATE
DANGER SCALE
click for danger scale
 
DANGER TREND: The danger remains steady.
The danger is LOW where the snowpack remains frozen throughout the day.
The danger raises to CONSIDERABLE, even HIGH, where the snowpack stays rotten overnight or becomes rotten during the day.
 
WEATHER: Cloudy with chance of showers - generally better than forecasted.
 
TRAVEL ADVISORY: Of all the snow types available now (cold, dry, new, old, corn and rotten) the snow that is the least fun and least safe is the rotten snow. Expect rotten snow in the lower elevations and slopes at all elevations warmed over the past month. Rotten snow in avalanche terrain is dangerous until it becomes corn snow (and even corn snow takes some management).
 
There is a bit of fresh snow that has fallen since Friday night in the upper elevations. Less than a inch at Mile 30, probably more closer to the port.
 
Snow-bridges covering glacier crevasses and bergschrunds are losing strength and sagging. If you choose to travel on glaciers, you need rescue and safe travel skills and gear. Beware of failing cornices. Stay well away from edges and limit your exposure beneath. Cornice fall is a large load and has the potential to trigger an avalanche.
  
AVALANCHE DISCUSSION: Wet loose avalanches remain expected in steep terrain. Wet slab avalanches also remain possible, especially as the day warms up.
 
Expect to see point releases of this weekend's new snow on south aspects and to find drifts of soft windslab (blown by light-moderate N-E wind) in the upper elevation.
 
The avalanche conditions of concern are:
1) point releases gouging old snow increasing mass and destructive potential
2) full snowpack releases to ground.
 
Post your observations <here>.
Avalanches are sized using the destructive scale <here>.
 
 
VALDEZ
 THOMPSON PASS
 24 Hour 
.04" rain
trace
April
5.1"
16"
Season Total
437.6"
656"
 Base
38"
104"
   
Snow load April 23rd measured by Valdez NWS is 89.2 pounds/square foot. 
 
CONFIDENCE: Fair.
 
Season Summary (written March 15) <here>
 
DEFINITIONS:
Snow climate zones:
  1. Maritime (Coastal) - from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  2. Inter-mountain (Transitional) - between Thompson Pass and Rendezvous Lodge.
  3. Continental (Interior) - the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
ELEVATIONS:
Lower - below 1500 feet
Mid - between 1500 and 3000 feet
Upper - above 3000 feet