Thursday-Sunday, April 24-27, 2014

Thursday-Sunday, April 24-27, 2014           Issued/Updated: 6:15 AM 4/24/14

thursday friday saturday & sunday
Variable Icon Variable Icon Variable Icon
DANGER SCALE

FORECASTER CONFIDENCE: GOOD

DANGER TREND: Generally the danger is increasing with the start of the spring shed avalanche cycle; variable due to time of day and elevation. During the heat of the day danger is heightened and decreases with overnight freezing.

AVALANCHE PROBLEM: Spring conditions create numerous avalanche problems from moist and wet surface snow avalanches to deep persistent slab releases, sometimes triggered by cornice failure.

icon-wet avalanches Loose Wet Avalanches as the snowpack warms during the day. Human triggered avalanches are expected where the snow is thawed. Problem Specific Travel Advisory - Plan your activity with the daily warming in mind. Stay away from steep southeast, south and southwest facing terrain as they become heated. Cold dry snow remains in the shaded upper elevations.

List of Avalanche Problems <here>

GENERAL TRAVEL ADVISORY: Travel on glaciers requires the gear and skills for crevasse rescue. Snow bridges are weakening.

AVALANCHES: Numerous wet loose slides to size 2.5 continue to run off sun affected aspects at all elevations. Photos below of icefall avalanche off 27 Mile Glacier Saturday April 19th.

27 Mile icefall

 

 

 

 

 

 

27 Mile glacier

 

 

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

 

WEATHER:  Broken skies with daytime temperatures in the 50′s. Light to moderate westerly wind in the afternoons. Cloud thickening by with a chance of moisture by Sunday.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>. Thompson Pass weather <here>.

SNOWPACK DISCUSSION:  What snowpack remains below treeline is becoming isothermal. Cloud cover overnight does not allow the snow to freeze.

All aspects at all elevations directly baked in the sun, thinner areas and around rocks, the snow is warming and potentially isothermal.

For how warm it’s been in the last few weeks, the shadowed snow in the upper elevations has been holding in there fairly well. Watch for pockets of windslab near ridgetops built in the last week by alternating northeast and southwest wind. Some might still be sensitive to riders.

With spring warming, facets from early February on the Damalanche crust could reactivate as a persistent deep slab problem –  monitoring natural activity, snowpack temperatures, and water percolation through the pack will help us know if this is an issue in the next couple weeks.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 24:

VALDEZ
THOMPSON PASS
24 Hour Snow
0″
0″
April Snow
?”
9″
Winter Total
?”
335″
Base
?”
60″
24 Hr Water Equivalent
?”
0″
April Water Equivalent
?”
0.7″
(Valdez NWS office has closed.)

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <here>

Season Summary from the beginning of winter to January 8 <here>

Snow climate zones:

  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains October through May

Free smart phone avalanche forecasts at: http://www.avalancheforecasts.com/

Monday to Thursday, April 21-24, 2014

Monday-Thursday, April 21-24, 2014                  Issued / Updated:8:00 AM 4/21/14

monday tuesday wednesday & thursday
Variable Icon Variable Icon Variable Icon
DANGER SCALE

FORECASTER CONFIDENCE: GOOD

DANGER TREND:  The danger is increasing with the start of the spring shed avalanche cycle. The danger increases during the heat of the day and decreases with overnight freezing.

AVALANCHE PROBLEM: Spring conditions create numerous avalanche problems from moist and wet surface snow avalanches to deep persistent slab releases, sometimes triggered by cornice failure.

icon-wet avalanches Loose Wet Avalanches as the snowpack warms during the day. Human triggered avalanches are expected where the snow is thawed. Problem Specific Travel Advisory - Plan your activity with the daily warming cycle in mind. Stay away from steep southeast, south and southwest facing terrain as they become heated. Cold dry snow remains in the shaded upper elevations.

List of Avalanche Problems <here>

GENERAL TRAVEL ADVISORY: Travel on glaciers requires the gear and skills for crevasse rescue. Snow bridges are weakening.

AVALANCHES: Numerous wet loose slides to size 2 continue to run off sun affected aspects at all elevations. Photos below of icefall avalanche off 27 Mile Glacier on Saturday April 19th.

27 Mile icefall

 

 

 

 

 

 

27 Mile glacier

 

 

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

 

 

WEATHER:  High pressure clear skies with daytime temperatures in the 50′s. Becoming cloudy. A chance of moisture over the weekend.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>. Thompson Pass weather <here>.

SNOWPACK DISCUSSION:  The snowpack is becoming isothermal (not frozen) in the lower elevations and on aspects at all elevations baked in the sun, especially where the snowpack is thinner and around rocks. In the upper elevations there remain windslabs and the potential persistent deep slab problem of the facets associated with the early February Damalanche crusts.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 23:

VALDEZ
THOMPSON PASS
24 Hour Snow
0″
0″
April Snow
?”
9″
Winter Total
?”
335″
Base
?”
60″
24 Hr Water Equivalent
?”
0″
April Water Equivalent
?”
0.7″
(Valdez NWS office is closing shop)

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <here>

Season Summary from the beginning of winter to January 8 <here>

Snow climate zones:

  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains October through May

Free smart phone avalanche forecasts at: http://www.avalancheforecasts.com/

Friday to Monday, April 18-21, 2014

Friday-Monday, April 18-21, 2014                  Issued / Updated:7:00 AM 4/18/14

friday saturday Sunday & moNday
Moderate-150x150 Variable Icon Variable Icon
DANGER SCALE

FORECASTER CONFIDENCE: FAIR

DANGER TREND:  The danger is increasing as we head into the start of the spring shed avalanche cycle.

AVALANCHE PROBLEM: Spring conditions create numerous avalanche problems from moist and wet snow avalanches to slab releases, sometimes triggered by cornice failure.

icon-wet avalanches Loose Wet Slides - The snowpack continues to warm and wet, loose snow is avalanching in the afternoons. Human triggered avalanches are expected where the snow is thawed. Until the skies clear, cloudy, warm weather insulates the snow at night preventing a solid refreeze.  Problem Specific Travel Advisory - Plan your tour with daily warming cycle in mind. Stay away from steep south facing terrain in the heat of the afternoon.

List of Avalanche Problems <here>

GENERAL TRAVEL ADVISORY:

  1. Travel on glaciers requires the gear and skills for crevasse rescue.
  2. Snow bridges are weakening.

AVALANCHES:

  • Warmer temperatures continue to trigger wet loose slides to size 2 on sun affected aspects at all elevations.

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

WEATHER:  As the weak system passes another 2-4 inches may accumulate in the upper elevations before the skies clear over the weekend and the daytime temperatures climb into the 50′s.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>. Thompson Pass weather <here>.

SNOWPACK DISCUSSION:  The snowpack is becoming isothermal (not frozen) in the lower elevations and on aspects at all elevations baked in the sun, especially where the snowpack is thinner and around rocks. In the upper elevations there remain windslabs and the potential persistent deep slab problem of the facets associated with the early February Damalanche crusts.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 18:

VALDEZ
THOMPSON PASS
24 Hour Snow
0″
2″
April Snow
?”
9″
Winter Total
?”
335″
Base
?”
66″
24 Hr Water Equivalent
?”
0.1″
April Water Equivalent
?”
0.6″
(Valdez NWS office is closing shop)

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <here>

Season Summary from the beginning of winter to January 8 <here>

Snow climate zones:

  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains October through May

Free smart phone avalanche forecasts at: http://www.avalancheforecasts.com/

Thursday-Sunday, April 17-20, 2014

Thursday-Sunday, April 17-20, 2014                  Issued / Updated:7:00 AM 4/17/14

THURSday FRIday SATURday & SUNday
Moderate-150x150 Moderate-150x150 Moderate-150x150
DANGER SCALE

FORECASTER CONFIDENCE: FAIR

DANGER TREND:  The danger will continue to increase slightly as we progress through this next forecast window.  A mix of direct sun and cloud-trapping radiation will deliver a variety of warm temperatures, rain and snow dependent on elevation. Freezing line will continue to hover around the 3,000′ elevation mark.   Any dramatic increase in rain will add stress to buried weak layers while new snow could create slab issues.

AVALANCHE PROBLEMS: Spring conditions create multiple, concurrent, avalanche problems. The most probable are listed.

icon-wet avalanches Loose Wet Slides - With freezing levels up to 3,000 feet, the snowpack continues to see significant warming.  Moist snow has been found nearly a half foot down at mid elevations and 2 feet down at 1,500′.  Wet, loose snow could easily be kicked off steep rollovers Tuesday afternoon in the lower elevations. Cloudy, warm weather insulates the snow at night and may not allow for a solid freeze.  Monitor for warming in the snow pack and note changes throughout your tour.

Problem Specific Travel Advisory - Plan your tour with daily warming cycle in mind. Stay off steep south facing terrain in the heat of the afternoon.

Wind-Slab icon Wind slab - Previously built wind slabs should begin to stabilize over time, but will be more sensitive in the afternoon heat. With significant precipitation in the forecast Friday, new slabs could form in higher, wind affected areas.

Problem Specific Travel Advisory - Keep your radar on for new and old slabs that have formed on lee slopes and spread out to manage them safely.

List of Avalanche Problems <here>

GENERAL TRAVEL ADVISORY:

  1. Choose terrain appropriate to your group’s ability and experience.
  2. Make a plan to manage sluff in steep terrain.
  3. Travel on glaciers requires the gear and skills for crevasse rescue.
  4. Snow bridges will be less stable on warm days in the afternoon.

AVALANCHES:

  • Warmer temperatures continue to trigger wet loose slides to size 2 on sun affected aspects on lower and mid elevation slopes.

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

WEATHER:  As a low pressure system gets pushed to the east just south of us, foresee SE winds to bring more clouds and weather Thursday night through Friday night. Expect scattered rain down low and a snow-rain mix up to 3,000′. Besides a cooler Friday, we may see the warmest days so far this season Thursday and over the weekend. The coastal region could hit the high 40′s. Winds will generally be light and prevail from the south Friday, but shift to the north Thursday and the weekend in combination with clearer skies.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>. Thompson Pass weather <here>.

SNOWPACK DISCUSSION:  Thompson Pass has seen a few new inches of snow and as much as 6-10 inches of new in the upper elevations. Fairly recent moderate to strong winds built wind slabs on multiple aspects during the first week of April. These wind slabs were reactive on W through NE aspects above 2,500 feet, sliding on near surface facets and surface hoar buried March 30th.  In lower areas the near surface facets are gaining strength with the spring daytime warming.  It is unknown how much strengthening is occurring in the upper elevations, but no events have been reported recently.

Monitoring the snowpack temperature and the moisture in the snowpack is important during the spring cycle.  Watch for little snowballs falling off of rocks.  Little snowballs will eventually turn into bigger snowballs, and both are precursors for a wet slab avalanche.  Compare your foot penetration throughout the day.  If you are sinking in calf deep in slushy snow, it is probably time to turn around.

A pit dug on lower Dimond <here> shows bonding between the Damalanche crust and the above snowpack.  However, well developed facets were still preserved above the crust.  Warm temperatures are being found East of the pass where the Damalanche facets are likely the largest in the forecasted region due to colder temperatures during the winter.  As water percolates down deep into the snow pack, the Damalanche crust may once again become a topic of discussion.

See the Snow Observations page for valuable current information. Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 17:

VALDEZ
THOMPSON PASS
24 Hour Snow
0″
0″
April Snow
?”
7″
Winter Total
?”
333″
Base
?”
65″
24 Hr Water Equivalent
?”
0″
April Water Equivalent
?”
0.6″
(Valdez NWS office is closing shop)

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <here>

Season Summary from the beginning of winter to January 8 <here>

Snow climate zones:

  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains through the avalanche season –  October through May Smart phone avalanche forecasts now available.  Download either the iOS or Android version of the app for free at: http://www.avalancheforecasts.com/

Wednesday-Saturday, April 16-19, 2014

Wednesday-Saturday, April 16-19, 2014                  Issued / Updated:7:45 AM 4/16/14

wednesday thursday friday & saturday
Moderate-150x150 Moderate-150x150 Moderate-150x150
DANGER SCALE

FORECASTER CONFIDENCE: FAIR

DANGER TREND:  The danger will increase slightly as we progress through this next forecast window.  Overcast skies will deliver rain and snow with a freezing level up to 3,000′.   Additional weight and moisture will add stress to the snowpack and buried weak layers.

AVALANCHE PROBLEMS: Spring conditions create multiple, concurrent, avalanche problems. The most probable are listed.

icon-wet avalanches

Loose Wet Slides - With freezing levels up to 3,000 feet, the snowpack has seen significant warming.  Moist snow has been found nearly a half foot down at mid elevations and 2 feet down at 1,500′.  Wet, loose snow could easily be kicked off steep rollovers yesterday afternoon in the lower elevations. Cloudy, warm weather insulates the snow at night and may not allow for a solid freeze.  Monitor for warming in the snow pack and note changes throughout your tour.

 

Wind-Slab icon

Wind slab - The previously built wind slab should begin to stabilize over time, but will be more sensitive in the afternoon heat. See avalanche activity for details on old slides involving south to northeast wind events. With more precipitation in the forecast, new slabs could form in higher, wind affected areas.

 

List of Avalanche Problems <here>

TRAVEL ADVISORY:

  1. Choose terrain appropriate to your group’s ability and experience. Increasing temperatures and rain are adding stress to the snowpack.
  2. Make a plan to manage sluff in steep terrain.
  3. Plan your tour with daily warming cycle in mind. Stay off steep south facing terrain in the heat of the afternoon.
  4. Travel on glaciers requires the gear and skills for crevasse rescue.
  5. Snow bridges will be less stable on warm days in the afternoon.

AVALANCHES:

  • Numerous new snow point releases to size 1 in the afternoon of the 15th.
  • Warmer temperatures have triggered wet loose slides to size 2 on sun affected aspects on steep lower and mid elevation slopes.

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

WEATHER:  Expect overcast conditions throughout our region Wednesday, with a chance for a broken sky Thursday during the day. More clouds and weather seems to be moving in Thursday night, but won’t last long as we can hope for clearer skies Friday night and into the weekend. This these overcast periods will continue to trap the daily solar radiation and lead to above freezing temperatures even at Thompson pass during the heat of the day. Expect scattered rain down low and a snow-rain mix up to 3,000′ Wednesday and Friday. Overnight lows will barely be reaching freezing in the coastal zones, while the pass may drop into the high teens to low 20′s. Expect winds to be light and prevailing from the south, but shift to the north Thursday and Saturday in combination with a chance of blue skies.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>.

Thompson Pass weather <here>.

SNOWPACK DISCUSSION:  There is a few inches of new snow at Thompson Pass and as much as 6-10 inches of new snow in the upper elevations. Moderate to strong winds from the south to northeast, built wind slabs on multiple aspects during the first week of April. These wind slabs were reactive on W through NE aspects above 2,500 feet, sliding on near surface facets and surface hoar buried March 30th.  In lower areas the near surface facets are gaining strength with the spring daytime warming.  It is unknown how much strengthening is occurring in the upper elevations.

Monitoring the snowpack temperature and the moisture in the snowpack is important during the spring cycle.  Watch for little snowballs falling off of rocks.  Little snowballs will eventually turn into bigger snowballs, and both are precursors for a wet slab avalanche.  Compare your foot penetration throughout the day.  If you are sinking in calf deep in slushy snow, it is probably time to turn around.

A pit dug on lower Dimond <here> shows bonding between the Damalanche crust and the above snowpack.  However, well developed facets were still preserved above the crust.  Warm temperatures are being found East of the pass where the Damalanche facets are likely the largest in the forecasted region due to colder temperatures during the winter.  As water percolates down deep into the snow pack, the Damalanche crust may once again become a topic of discussion.

See the Snow Observations page for valuable current information. Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 16:

VALDEZ
THOMPSON PASS
24 Hour Snow
0″
1″
April Snow
?”
7″
Winter Total
?”
333″
Base
?”
66″
24 Hr Water Equivalent
?”
0.1″
April Water Equivalent
?”
0.6″
(Valdez NWS office is closing shop)

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <here>

Season Summary from the beginning of winter to January 8 <here>

Snow climate zones:

  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains through the avalanche season –  October through May

Smart phone avalanche forecasts now available.  Download either the iOS or Android version of the app for free at: http://www.avalancheforecasts.com/

Tuesday-Friday, April 15-18, 2014

Tuesday-Friday, April 15-18, 2014                  Issued / Updated:7:00 AM 4/15/14

tuesday wednESday thurSday & friday
Moderate-150x150 Moderate-150x150 Moderate-150x150
DANGER SCALE

FORECASTER CONFIDENCE: FAIR

DANGER TREND:  The danger will increase slowly as we progress through this next forecast window.  Overcast skies will deliver rain and snow with a freezing level up to 3,000′.   Additional weight and moisture will add stress to the snowpack and buried weak layers.

AVALANCHE PROBLEMS: Spring conditions create multiple, concurrent, avalanche problems. The most probable are listed.

Wind-Slab icon

Wind slab - The previously built wind slab should begin to stabilize over time but will be more sensitive in the afternoon heat. See avalanche activity for details on old slides involving south to northeast wind events.

 

 

icon-wet avalanches

Loose Wet Slides - With freezing levels up to 3,000 feet, the snowpack will see significant warming.  Moist snow has been found a half foot down at mid elevations.  Cloudy, warm weather insulates the snow at night and may not allow for a solid freeze.  Monitor for warming in the snow pack and note changes throughout your tour.

 

List of Avalanche Problems <here>

TRAVEL ADVISORY:

  1. Choose terrain appropriate to your group’s ability and experience. Increasing temperatures and rain are adding stress to the snowpack.
  2. Make a plan to manage sluff in steep terrain.
  3. Plan your tour with daily warming cycle in mind. Stay off steep south facing terrain in the heat of the afternoon.
  4. Travel on glaciers requires the gear and skills for crevasse rescue.
  5. Snow bridges will be less stable on warm days in the afternoon.

AVALANCHES:

  • Last week there were numerous skier triggered wind slab avalanches to destructive size 2 on NW-NE aspects above 3000 feet elevation north of Thompson Pass with slabs to 12 inches thick running on buried surface hoar and near surface facets.
  • Above freezing temperatures Monday April 7 likely contributed to a skier-triggered destructive size 2.5 avalanche in the maritime zone south of Keystone Canyon: 2500′, NNW aspect, ~37 degree slope. The foot thick slab was variable in hardness from soft to hard and ran on near-surface facets with some small pockets that stepped down to old Damalanche facets.
  • Wet loose slides have been observed in the last week on east, south, and west aspects on steep lower and mid elevation steeps.

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

WEATHER:  Overcast conditions are forecasted throughout our region for the next few days, with a chance for a break by Thursday. This weather will continue to trap the daily solar radiation and lead to above freezing temperatures even at Thompson pass during the heat of the day. Expect scattered rain down low and a snow-rain mix up to 3,000′. Overnight lows will barely be reaching freezing in the coastal zones, while the pass may drop into the high teens. Expect winds to be light and prevailing from the north, but a shift to the south is likely Wednesday and into Thursday.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>.

Thompson Pass weather <here>.

SNOWPACK DISCUSSION:  Moderate to strong winds from the south to northeast, built wind slabs on multiple aspects during the first week of April. These wind slabs were reactive on W through NE aspects above 2,500 feet, sliding on near surface facets and surface hoar buried March 30th.  In lower areas the near surface facets are gaining strength with the spring daytime warming.  It is unknown how much strengthening is occurring in the upper elevations.

Monitoring the snowpack temperature and the moisture in the snowpack is important during the spring cycle.  Watch for little snowballs falling off of rocks.  Little snowballs will eventually turn into bigger snowballs, and both are precursors for a wet slab avalanche.  Compare your foot penetration throughout the day.  If you are sinking in calf deep in slushy snow, it is probably time to turn around.

A pit dug on lower diamond shows bonding between the Damalanche crust and the above snowpack.  However, well developed facets were still preserved above the crust.  Warm temperatures are being found East of the pass where the Damalanche facets are likely the largest in the forecasted region due to colder temperatures during the winter.  As water percolates down deep into the snow pack, the Damalanche crust may once again become a topic of discussion.

*See recent snow profile and test results from April 13, 2014 below Diamond.

See the Snow Observations page for valuable current information. Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 15:

VALDEZ
THOMPSON PASS
24 Hour Snow
0″
trace
April Snow
?”
6″
Winter Total
?”
332″
Base
?”
65″
24 Hr Water Equivalent
?”
0.1″
April Water Equivalent
?”
0.5″
(Valdez NWS office is closing shop)

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <here>

Season Summary from the beginning of winter to January 8 <here>

Snow climate zones:

  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains through the avalanche season –  October through May

Smart phone avalanche forecasts now available.  Download either the iOS or Android version of the app for free at: http://www.avalancheforecasts.com/

Monday-Thursday, April 14-17, 2014

Monday-Thursday, April 14-17, 2014                  Issued / Updated: 9:00 AM 4/14/14 

MONday TUESday WEDNESday & THURSday
Moderate-150x150 Moderate-150x150 Moderate-150x150
DANGER SCALE

FORECASTER CONFIDENCE: FAIR

DANGER TREND:  The danger will increase slowly as we progress through this next forecast window.  Overcast skies will deliver a variety of rain and snow while creating temperatures above freezing up to 3,000′. Additional weight and moisture in the snowpack will lead to heightened sensitivity of buried weak layers.

AVALANCHE PROBLEMS: Spring conditions create multiple, concurrent, avalanche problems. The most probable are listed.

Wind-Slab icon

Wind slab - Moderate to strong winds from south to northeast, have built wind slabs in mid to high elevation, exposed terrain on multiple aspects. These wind slabs have been reactive above 2,500′ on West through Northeast aspects and are sliding on near surface facets and surface hoar buried March 30th.

 

 

icon-wet avalanches

Loose Wet Slides - Above freezing temperatures will continue to affect the snow up to the 3,000′ elevation mark the next few days. Cloudy nights will trap heat from the day, preventing a solid freeze at night. Constantly monitor the strength and wetness of the snow as the day progresses. Additional moisture and melting bonds within the snowpack could lead to problems with old weak layers, most notably the faceted layer just above the Damalanche crust.

List of Avalanche Problems <here>

TRAVEL ADVISORY:

  1. Choose terrain appropriate to your group’s ability and experience.
  2. Make a plan to manage sluff in steep terrain.
  3. Plan your tour with daily warming cycle in mind. Stay off steep south facing terrain in the heat of the afternoon.
  4. Travel on glaciers requires the gear and skills for crevasse rescue.
  5. Snow bridges will be less stable on warm days in the afternoon.

AVALANCHES:

  • There have been multiple reports of skier triggered, wind slab avalanches to destructive size 2 on localized features at the mid to high elevations north of the Pass. Most seem to be occurring on NW-NE aspects steeper than 38 degrees. The slabs tend to be 8-12 inches thick and seem to be running on buried surface hoar and near surface facets.
  • Above freezing temperatures Monday April 7 likely contributed to a skier-triggered destructive size 2.5 avalanche in the maritime zone south of Keystone Canyon: 2500′, NNW aspect, ~37 degree slope. The foot thick slab was variable in hardness from soft to hard and ran on near-surface facets with some small pockets that stepped down to old Damalanche facets.
  • Wet loose slides have been observed in the last week on east, south, and west aspects on steep lower and mid elevation steeps.

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

WEATHER:  Overcast conditions are forecasted throughout our region for the next few days, with a chance for a break by Thursday. This weather will continue to trap the daily solar radiation and lead to above freezing temperatures even at Thompson pass during the heat of the day. Expect scattered rain down low and a snow-rain mix up to 3,000′. Overnight lows will barely be reaching freezing in the coastal zones, while the pass may drop into the high teens. Expect winds to be light and prevailing from the north, but a shift to the south is possible Wednesday and into Thursday.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>.

Thompson Pass weather <here>.

SNOWPACK DISCUSSION: 6-16″ storm snow from March has been found in the mid-upper elevations of our region in the last few days. Since the snow fell, moderate to strong winds that varied in direction from south to northeast, have built wind slabs in exposed terrain on multiple aspects. These windslabs have been found to be reactive on W through NE aspects where it seems to be sliding on near surface facets and surface hoar buried March 30th. Manage your terrain wisely if you are venturing into areas that hold similar traits above the 2,500 feet elevation mark. New snow and possibly rain, is in the forecast, this will add stress to the weak layers and make things more sensitive or even release naturally.

An additional prominent avalanche concern this week will be continued spring warming. Moderate temperatures and gradual warming promotes strengthening of the snowpack, but extreme temperature swings can quickly weaken it and lead to wet slides. As the weather warms and more water moves through the snow, future activity down near the Damalanche crust is possible. The forecasted temperatures may not re-freeze the snow overnight in the mid and lower elevations.

*See recent snow profile and test results from April 13, 2014 below Dimond.

See the Snow Observations page for valuable current information. Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 14:

 
VALDEZ
THOMPSON PASS
24 Hour Snow
0″
1″
April Snow
?”
6″
Winter Total
?”
332″
Base
?”
66″
24 Hr Water Equivalent
?”
0.1″
April Water Equivalent
?”
0.4″
(Valdez NWS office is closing shop)    

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <here>

Season Summary from the beginning of winter to January 8 <here>

Snow climate zones:

  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains through the avalanche season –  October through May

Smart phone avalanche forecasts now available.  Download either the iOS or Android version of the app for free at: http://www.avalancheforecasts.com/

Sunday-Wednesday, April 13-16, 2014

Sunday-Wednesday, April 13-16, 2014                  Issued/updated April 13 10:00am

Sunday monday TUESday & Wednesday
Moderate-150x150 Moderate-150x150 Moderate-150x150
DANGER SCALE

DANGER TREND:  The danger increases as we move into our next forecasted period.  Between three to five inches of snow is expected in the next four days.  As the temperatures warm to near freezing at the Pass by Wednesday, stress will be added to both the snowpack and the newly deposited snow.

AVALANCHE PROBLEMS: Spring conditions create multiple, concurrent, avalanche problems. The most probable are listed.

Wind-Slab icon

Wind slab - Moderate to strong winds from south to northeast, have built wind slabs in mid to high elevation, exposed terrain on multiple aspects. These wind slabs have been reactive on West through Northeast aspects likely sliding on near surface facets and surface hoar buried March 30th.

 

icon-wet avalanches

Loose Wet Slides - The temperatures will warm to near freezing at Thompson Pass by Wednesday with a chance of rain. Cloudy nights will trap heat from the day, preventing a solid freeze at night. Monitor how solid the snow is in the morning and continue to do so as the day progresses.

List of Avalanche Problems <here>

 

TRAVEL ADVISORY:

  1. Choose terrain appropriate to your group’s ability and experience.
  2. Make a plan to manage sluff in steep terrain.
  3. Plan your tour with daily warming cycle in mind. Stay off steep south facing terrain in the heat of the afternoon.
  4. Travel on glaciers requires the gear and skills for crevasse rescue.
  5. Snow bridges will be less stable on warm days in the afternoon.

AVALANCHES:

  • There have been multiple reports of skier triggered, wind slab avalanches to destructive size 2 on localized features at the mid to high elevations north of the Pass. Most seem to be occurring on NW-NE aspects steeper than 38 degrees. The slabs tend to be 8-12 inches thick and seem to be running on buried surface hoar and near surface facets.
  • Above freezing temperatures Monday April 7 likely contributed to a skier-triggered destructive size 2.5 avalanche in the maritime zone south of Keystone Canyon: 2500′, NNW aspect, ~37 degree slope. The foot thick slab was variable in hardness from soft to hard and ran on near-surface facets with some small pockets that stepped down to old Damalanche facets.
  • Wet loose slides have been observed in the last week on east, south, and west aspects on steep lower and mid elevation steeps.

Please contribute to the Snow Observations page.

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

WEATHER:  Partly cloudy to cloudy skies will dominate the forecasted period.  The system will bring light precipitation with up to 3 inches of snow at the pass by Monday morning.  Less than an inch a day is forecasted at the pass for Tuesday and Wednesday.  However on Wednesday the snow may turn to light rain as temperatures increase to near freezing.  In the coastal zone, night time temperatures will barely dip below freezing by Wednesday.  Winds are forecasted as light and variable, with light SE winds on Sunday.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>.

Thompson Pass weather <here>.

SNOWPACK DISCUSSION: 6-16″ storm snow from March has been found in the mid-upper elevations of our region in the last few days. Since the snow fell, moderate to strong winds that varied in direction from south to northeast, have built wind slabs in exposed terrain on multiple aspects. These windslabs have been found to be reactive on W through NE aspects where it seems to be sliding on near surface facets and surface hoar buried March 30th. Manage your terrain wisely if you are venturing into areas that hold similar traits above the 2,500 feet elevation mark. New snow and possibly rain, is in the forecast, this will add stress to the weak layers and make things more sensitive or even release naturally.

An additional avalanche concern this weekend and into next week will be continued spring warming. Moderate temperatures and gradual warming promotes strengthening of the snowpack, but extreme temperature swings can quickly weaken it and lead to wet slides. As the weather warms and more water moves through the snow, future activity down near the Damalanche crust is possible. The forecasted temperatures may not re-freeze the snow overnight in the mid and lower elevations.

See the Snow Observations page for valuable current information. Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 13:

 
VALDEZ
THOMPSON PASS
24 Hour Snow
0″
0″
April Snow
?”
6″
Winter Total
?”
331″
Base
?”
66″
24 Hr Water Equivalent
?”
0″
April Water Equivalent
?”
0.3″
(Valdez NWS office is closing shop)    

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <hereSeason Summary from the beginning of winter to January 8 <here>

FORECASTER CONFIDENCE: FAIR

Smart phone avalanche forecasts now available.  Download either the iOS or Android version of the app for free at: http://www.avalancheforecasts.com/

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains through the avalanche season –  October through May

Snow climate zones:
  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

Saturday-Tuesday, April 12-15, 2014

Saturday-Tuesday, April 12-15, 2014

SATURday SUNday MONDAY & TUESday
Moderate-150x150 Moderate-150x150 Moderate-150x150
DANGER SCALE

DANGER TREND: Expect the danger trend to remain steady over the next few days since newly deposited wind slabs have formed on top of weak layers that may be slow to stabilize. New precipitation this weekend will bring additional weight and stress to these buried weak layers. Expect the danger to increase in the afternoons due to solar radiation and daily warming.

AVALANCHE PROBLEMS: Spring conditions create multiple, often concurrent, avalanche problems. Our primary concerns are listed below:

Wind-Slab icon

Wind slab - Moderate to strong winds at higher elevations have moved the new snow in multiple directions in the last few days.  A northerly outflow wind has prevailed with stints of southerly winds since the most recent precipitation Tuesday night. These wind slabs are not bonded well with the near surface facets (sugar snow) and surface hoar on northerly aspects. As you choose your lines, consider ridge top and cross loading effects. (See AVALANCHES below for more details)

icon-wet avalanches

Loose Wet Slides - Prolonged solar radiation warms the snowpack throughout the day and weakens the snow structure near the surface until it is refrozen overnight. In the lower elevations, temperatures may not dip low enough to solidly refreeze the snow surface.

List of Avalanche Problems <here>

 

TRAVEL ADVISORY:

  1. Choose terrain appropriate to your group’s ability and experience.
  2. Make a plan to manage sluff in steep terrain.
  3. Plan your tour with daily warming cycle in mind: stay off steep south facing terrain in the heat of the afternoon.
  4. Travel on glaciers requires the gear and skills for crevasse rescue.
  5. Snow bridges will be less stable on warm days in the afternoon.

AVALANCHES:

  • There have been multiple reports of skier triggered, wind slab avalanches to destructive size 2 on localized features at the mid to high elevations north of the Pass. Most seem to be occurring on NW-NE aspects steeper than 38 degrees. The slabs tend to be 8-12 inches thick and seem to be running on buried surface hoar and near surface facets.
  • Above freezing temperatures Monday March 31 likely contributed to a skier-triggered destructive size 2.5 avalanche in the maritime zone south of Keystone Canyon: 2500′, NNW aspect, ~37 degree slope. The foot thick slab was variable in hardness from soft to hard and ran on near-surface facets with some small pockets that stepped down to old Damalanche facets.
  • Wet loose slides have been observed in the last week on east, south, and west aspects on steep lower and mid elevation steeps.

Please contribute to the Snow Observations page.

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

WEATHER:  Outflow wind will decrease and clouds will begin to build Saturday. We could see some precipitation Sunday-Tuesday.  As this front moves in, cooler days and warmer nights will be more prominent in the coastal areas as we will see temperatures barely dip below freezing at night. The temperatures on the Pass will continue to be near freezing during the day and increase at night from the high teens to the low 20′s.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>.

Thompson Pass weather <here>.

SNOWPACK DISCUSSION: 6-16″ storm snow from March  has been found in the mid-upper elevations of our region in the last few days. Since the snow fell, moderate to strong winds that varied in direction from south to northeast, have built wind slabs in exposed terrain on multiple aspects. These windslabs have been found to be reactive on W through NE aspects where it seems to be sliding on near surface facets and surface hoar buried March 30th. Manage your terrain wisely if you are venturing into areas that hold similar traits above the 2,500 feet elevation mark. New snow and possibly rain, is in the forecast, this will add stress to the weak layers and make things more sensitive or even release naturally.

An additional avalanche concern this weekend and into next week will be continued spring warming. Moderate temperatures and gradual warming promotes strengthening of the snowpack, but extreme temperature swings can quickly weaken it and lead to wet slides. As the weather warms and more water moves through the snow, future activity down near the Damalanche crust is possible. The forecasted temperatures may not re-freeze the snow overnight in the mid and lower elevations.

See the Snow Observations page for valuable current information. Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 12:

VALDEZ
THOMPSON PASS
24 Hour Snow
0″
0″
April Snow
?”
6″
Winter Total
?”
331″
Base
?”
66″
24 Hr Water Equivalent
?”
0″
April Water Equivalent
?”
0.3″
(Valdez NWS office is closing shop)

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <hereSeason Summary from the beginning of winter to January 8 <here>

FORECASTER CONFIDENCE: FAIR

Smart phone avalanche forecasts now available.  Download either the iOS or Android version of the app for free at: http://www.avalancheforecasts.com/

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains through the avalanche season –  October through May

Snow climate zones:
  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet

Thursday-Sunday, April 10-13, 2014

Thursday-Sunday, April 10-13, 2014

Thursday Friday SATURDAY & Sunday
Moderate-150x150 Moderate-150x150 Moderate-150x150
DANGER SCALE

DANGER TREND: Expect the danger trend to remain steady over the next few days as moderate winds continue to move new snow near the ridgetops. Danger will increase in the afternoons due to the strength of solar radiation and daily warming.

AVALANCHE PROBLEMS: Spring conditions create various avalanche problems

Wind-Slab icon

Wind slab - The wind has been moving the new snow in multiple directions in the last couple of days.  A northerly outflow wind prevailed Monday, a southeast wind Tuesday, and switched back to northerly on Tuesday night.  Slabs will be especially unstable when deposited over near surface facets (sugar snow).

 

 

icon-wet avalanches

 

Loose Wet Slides - Prolonged solar radiation warms the snowpack throughout the day and weakens the snow structure near the surface until it is refrozen overnight.

 

 

loose_snow_icon

 

Loose Snow - Significant new snow has accumulated at the upper elevations.

 

 

 

Persistent-Slab

 

Persistent Slab - Buried near surface facets have shown to be reactive in areas with possible step downs to the Damalanche crust.

 

 

 

cornice fall

 

Cornice Fall - Larger than normal cracks are developing behind cornices.  Give them wide berth.

 

 

List of Avalanche Problems <here>

TRAVEL ADVISORY: Choose terrain appropriate to your group’s ability and experience. Make a plan to manage sluff in steep terrain. Plan your tour with daily warming in mind.  Stay off of steep south facing terrain in the heat of the afternoon.  Travel on glaciers requires the gear and skills for crevasse rescue.  Snow bridges will be less stable on warm days in the afternoon.

AVALANCHES:  Above freezing temperatures Monday likely contributed to a skier-triggered destructive size 2.5 avalanche in the maritime zone south of Keystone Canyon: 2500′, NNW aspect, ~37 degree slope. The foot thick slab was variable in hardness from soft to hard and ran on near-surface facets with some small pockets that stepped down to old Damalanche facets.  This avalanche reminds us that we do have weak layers within our snowpack that can reactivate as the spring progresses.

Wet loose slides were observed Monday on east, south, and west facing aspects on lower and mid elevation steeps.

Loose slides were observed off the NW face of Embick Peak above the Port on Wednesday.

Please contribute to the Snow Observations page.

Avalanches are sized using the destructive scale <here>; see also an avalanche size estimation aid <here>.

WEATHER:  Sunny days and cold clear nights will prevail through Thursday and most of Friday with moderate to strong northerly winds at the pass.  The winds become light and variable late on Friday continuing through Sunday.  The temperature trend is increasing throughout the forecasted period, with temps possibly rising to freezing at the pass by Sunday.  A small front is expected to arrive this weekend bringing overcast skies and up to 2 inches of snow.

UAF has a high elevation weather station <data here> at 6600 feet above the Valdez Glacier <map here>.

Thompson Pass weather <here>.

SNOWPACK DISCUSSION: Up to 10″ new snow since has freshened the surfaces in the mid-upper elevations since Sunday March 30. North wind Monday swinging to the southeast Monday night and back to North on Tuesday night built wind slab in exposed terrain on multiple aspects. The winds will be moderate to strong from the North through Thursday, so expect continued loading.

The driving factor in avalanche concerns this week will be continued spring warming. Gradual warming promotes rounding and strengthening.  Warming also strengthens the slab closer to the surface while adding tension or stress on weak layers below. The weak layer of concern is the new windslab and old near surface facet/crust interface that was buried March 30. Reactivity at the Damalanche crust is still of interest.

Afternoon warming decreases the strength of the surface layers, leading to wet loose activity on steep terrain. With extended warming, wet slab avalanches are possible. This time of year, constant monitoring of the warming snowpack is prudent.  Warming will be significant in the afternoons this forecast period, especially with temps rising to near freezing at the pass.

See the Snow Observations page for valuable current information. Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 10:

VALDEZ
THOMPSON PASS
24 Hour Snow
0″
0″
April Snow
?”
6″
Winter Total
?”
331″
Base
?”
66″
24 Hr Water Equivalent
?”
0″
April Water Equivalent
?”
0.3″
(Valdez NWS office is closing shop)

April 1st Snow Survey: Valdez is 38 inches deep with 14 inches of water (36%), Milepost 18 is 45 inches deep with 16 inches of water (36%), Worthington Glacier is 66 inches deep with 24 inches of water (36%), and Milepost 37 is 51 inches deep with 15 inches of water (30%).

Summary of avalanche cycle January 13-30 <hereSeason Summary from the beginning of winter to January 8 <here>

FORECASTER CONFIDENCE: FAIR

Smart phone avalanche forecasts now available.  Download either the iOS or Android version of the app for free at: http://www.avalancheforecasts.com/

2014 marks the ninth year of public avalanche safety bulletins for the Valdez Chugach mountains through the avalanche season –  October through May

Snow climate zones:
  • Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Elevations:
  • Below treeline – below 2000 feet
  • Above treeline – above 2000 feet