Friday-Monday, February 27-March 2, 2015

FRIDAY SATURDAY  SUNDAY & MONDAY
        
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: MODERATE danger due to fresh windslab.
  • Mid Elevations: LOW danger.
  • Below treeline:  LOW danger.

DANGER TREND:  Steady as old slabs bond, yet new weakly connected slabs form.

AVALANCHE FORECASTER CONFIDENCE:   Good

AVALANCHE PROBLEM:  

Wind-Slab icon

Wind Slab Avalanches -  While the large amount of snow from the February 21-24 storm has been able to setup well, consistently moderate winds have been flagging the higher peaks and drifting snow into new slabs that are not bonded as well. These slabs are found near exposed ridgetops and faces that have been affected by the Northeast wind.

 

List of Avalanche Problems <here>

TRAVEL ADVISORY:    Critical macro and micro-terrain selection will allow you to hunt down preserved snow or subjugate yourself to dangerous, breakable windslab that tries to eat your skis and throw you off balance. These slabs are and will continue to form on western slopes lee to the prominent northeast wind. Evaluate the firmness of these slabs, what lies beneath and their ability to support propagation. Human triggered wind slab avalanches are possible and unpredictable.

Lower down, exposed, wind scoured rain crust makes for constantly changing conditions.

Get down in the snow and evaluate the conditions, expose as few people as possible and have a backup plan. This also pertains to spreading out and giving other parties space. This is a large range with endless options, yet some groups have been seen cutting a slope that others are already on. Please mind the avalanche dangers this entails and give space considering the possibility that the slope could slide and catch many people.

AVALANCHE ACTIVITY:   

Tuesday-Thursday: When skies cleared, widespread storm related loose avalanches were seen. Mostly on slopes steeper than 40 degrees. A few dry snow avalanches made the transition into the moist snow at lower elevations and ran down into alder. Several storm slab avalanches to size D2.5 were reported from the upper elevations (many steep northern aspect faces such as Catcher’s Mitt and Saphire) – that went during the storm.

Steep pockets of fresh windslab have been reported popping off near ridgelines where the north wind was moving storm snow. On Thursday, surface slabs were not bonding well, yet propagation was not supported. This could quickly change as the slabs get thicker and more rigid.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:  Many people were out slope testing the last few days with sunny skies. Moderate northeast winds quickly took the storm snow and loaded breakable wind slabs on top from Wednesday to Thursday. There are probably some preserved areas out there, but knowing terrain’s exposure to the wind is key to find them.

Thursday, upper elevation snow in Dimond’s Gunbarrels found newly formed wind slabs were not bonding well to underlying layers, but would break locally and not propagate. Deeper down, storm slab layers were evaluated and despite some weak interfaces at density breaks, they were bonding decently with hard ECTN test results on almost planar surfaces with slight steps.

The February 21-24 storm helped remove weak layering in our mid elevations and overall, sped up strengthening of our unseasonally shallow snowpack. In the upper elevations snowpack depth will now be on par with previous years, expect ~6 feet on the ground above 4000′.

Monitor the Feb.21-24 storm snow interface,  any residual facets from early February, and any deeper crust/facet combos that may still be present.

Interior of MP 37 and further toward the Tonsina Glacier, the snowpack is known to be generally shallower and colder. Any reports from those areas are appreciated.

Check out the detailed observations <here>.

WEATHER:   Expect clouds to move in Friday night with dusting of new snow Saturday, then clear again Sunday. Clouds will build again Monday for more precipitation to arrive Tuesday. 30 mph winds will shift and back down this afternoon and Saturday as weather moves in, then bump back up Sunday from the northeast. Highs will top freezing again in Valdez while in the 20’s near Thompson Pass.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/27 AM
 Thompson Pass – 2/26 AM
 Current Snow Depth  18″  43″
24 Hour Snow / Water Equiv. 0″ / 0″
0″ / 0″
Storm Snow / Water: 2/21-24 0″ / 0″ 12″ / 3.6″
February Snow / Water Equiv. 5.6″ / 4.5″ 37″ / 5″
Total Winter Snowfall / Water Equiv.
82″ / 15.1″ 242″ / 26.3″
Snowload in Valdez 20.8 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

February 26-March 1, 2015

THURSDAY FRIDAY  SATURDAY & SUNDAY
        
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: MODERATE danger due to fresh windslab.
  • Mid Elevations: LOW danger.
  • Below treeline:  LOW danger.

DANGER TREND:  Steady

AVALANCHE FORECASTER CONFIDENCE:   Fair

AVALANCHE PROBLEM:  

Wind-Slab icon

Wind Slab and Storm Slab Avalanches -  Three feet of February 21-24 storm snow at 4300 feet elevation and reports of up to five feet above. Near exposed ridgetops and peaks the storm snow is drifting with light to moderate Northeast wind.

 

List of Avalanche Problems <here>

TRAVEL ADVISORY:    Human triggered wind slab avalanches are possible on steep wind loaded slopes near ridge lines and peaks. Watch for flagging off peaks and areas where localized channeling of the north wind is cross loading lee slopes. Western gully walls in the Thompson Pass corridor are often where humans trigger wind slab avalanches under these conditions.

Even in wind protected areas, have a plan for rescue if the un-expected occurs. A three-four foot storm slab could produce a big slide. To reduce your consequences, analyze the terrain for potential terrain traps. Choose options that will spread debris out rather than pile it up deep.

AVALANCHE ACTIVITY:   Wednesday steep pockets of fresh windslab were popping off near ridgelines where the north wind was moving storm snow. These were prevelent near Thompson Pass where crossloading and toploading was active. This same activity will continue while the North wind moves snow available for transport. 

Tuesday-Wednesday when skies cleared, widespread storm related loose avalanches were seen. Mostly on slopes steeper than 40 degrees. A few dry snow avalanches made the transition into the moist snow at lower elevations and ran down into alder. A few unconfirmed storm slab avalanches to size D2.5 were reported from the upper elevations – these most likely went during the storm.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:  A fair bit of slope testing was done Wednesday by riders getting out to enjoy a sunny powder day. The only reports of unstable snow was where the storm snow was actively being windloaded by North wind. More observations across our forecast region will increase our confidence and understanding of the snowpack.

The February 21-24 storm helped remove weak layering in our mid elevations and overall, sped up strengthening of our unseasonally shallow snowpack. In the upper elevations snowpack depth will now be on par with previous years, expect ~6 feet on the ground above 4000′.

Monitor the Feb.21-24 storm snow interface,  any residual facets from early February, and any deeper crust/facet combos that may still be present.

Interior of MP 37 and further toward the Tonsina Glacier, the snowpack is known to be generally shallower and colder. Any reports from those areas are appreciated.

Check out the detailed observations <here>.

WEATHER:   Clear high pressure to hold through Saturday. At ridge tops and passes where outflow winds are channeled, expect North-Northeast wind to 35 mph Thursday. Highs in the 30sF in Valdez with high 20s near Thompson Pass. A few flurries will come in Sunday with another low pressure moving in Monday.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/25 AM
 Thompson Pass – 2/26 AM
 Current Snow Depth  18″  43″
24 Hour Snow / Water Equiv. 0″ / 0″
0″ / 0″
Storm Snow / Water: 2/21-24 0″ / 0″ 12″ / 3.6″
February Snow / Water Equiv. 5.6″ / 4.5″ 37″ / 5″
Total Winter Snowfall / Water Equiv.
82″ / 15.1″ 242″ / 26.3″
Snowload in Valdez 20.8 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

Wednesday- Saturday, February 25-28, 2015

WEDNESDAY THURSDAY  FRIDAY & SATURDAY
        
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: MODERATE danger.
  • Mid Elevations: MODERATE danger.
  • Below treeline:  MODERATE danger.

DANGER TREND:  The danger is steady as temperatures cool and storm snow settles.

AVALANCHE FORECASTER CONFIDENCE:   Good

AVALANCHE PROBLEM:  

Storm Snow Slab Avalanches -   with three feet of new snow at 4300 feet elevation and reports of five feet higher up from the February 21-24 storm snow. The storm snow was drifted with light to moderate wind from the southeast during the storm and is now being drifted by moderate northerly winds.

 

List of Avalanche Problems <here>

TRAVEL ADVISORY:    As many accidents occur just after storms, be conservative in avalanche terrain. If you’re enjoying powder in higher elevations, slough management may be necessary in very steep terrain.

AVALANCHE ACTIVITY:    Natural avalanche activity occurred Sunday and Monday February 22-23 across the forecast region with a few avalanches to size D3 reaching the valley floor. Storm slab releases from the upper and mid-elevation entrained moist and wet snow in the lower elevations. A number of wet snow avalanches released in the lower elevations.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:  The past storm deposited a foot of snow at 2500 feet elevation and substantially more in higher elevations. Four inches of rain fell at sea level. As is typical, the amount of deposited precipitation decreased from the Maritime to the Continental snow climate zones. Thompson Pass received 3.5 inches of water including a foot of snow. Thus the snowpack at “the gap” is isothermic, mostly rotten, topped with a foot of fresh snow. As temperatures cool, wet snow found below the freezing level (3500-4000′) will begin to freeze and solidify.

The Feb.21-24 Pineapple Express storm elevated the freezing level possibly as high as 5000 feet on the 22nd. The storm snow was drifted by moderate southeast winds. We have received reports (but no complaints) of 3-5 feet of powder in high elevations. Snowpit testing (ECT) at 4300 feet resulted in a few resistant shears within the storm snow which did not propagate. Expect the snowpack conditions to be excellent riding until the wind begins acting on the snowpack developing wind slab.

Check out the detailed observations <here>.

WEATHER:   As the storm dissipates and warm air recedes from SouthCentral Alaska, you will notice the development of a high pressure weather regime. The clouds are moving out, and cooling temperatures will drop the freezing level down to sea level once again. Thompson Pass temperatures are forecasted to be in the high twenties Fahrenheit.  Wednesday afternoon North East outflow wind will develop to 25-40mph, peaking in velocity Thursday morning. Visibility may be reduced Wednesday morning due to fog; the last remnant of storm. No new precipitation is expected during the forecast period.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/25 AM
 Thompson Pass – 2/25 AM
 Current Snow Depth  18″  45″
24 Hour Snow / Water Equiv. 0″ / 0″
0″ / 0″
Storm Snow / Water: 2/21-24 0″ / 0″ 12″ / 3.6″
February Snow / Water Equiv. 5.6″ / 4.5″ 37″ / 5″
Total Winter Snowfall / Water Equiv.
82″ / 15.1″ 242″ / 26.3″
Snowload in Valdez 20.8 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

Tuesday-Friday, February 24-27, 2015

TUESDAY WEDNESDAY  THURSDAY & Friday
        
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: CONSIDERABLE danger.
  • Mid Elevations: CONSIDERABLE danger.
  • Below treeline:  CONSIDERABLE danger.

DANGER TREND:  The danger is decreasing as temperatures cool and storm snow settles.

AVALANCHE FORECASTER CONFIDENCE:   Good

AVALANCHE PROBLEM:  

Storm Snow Slab Avalanches -   above 3500′ with February 21-24 storm snow with light to moderate wind from the southeast.

 

 

List of Avalanche Problems <here>

TRAVEL ADVISORY:    As many accidents occur just after storms, be conservative in avalanche terrain.

AVALANCHE ACTIVITY:    Avalanche activity occurred Sunday and Monday February 22-23 across the forecast region with a few avalanches to size D3 reaching the valley floor. Storm slab releases from the upper and mid-elevation entrained moist and wet snow in the lower elevations. A number of wet snow avalanches released in the lower elevations.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:   The past storm deposited a foot of snow at 2500 feet elevation and likely substantially more in the elevations, possibly as much as five feet. Four inches of rain fell at sea level. The amount of precipitation decreased inland. Thompson Pass received 3.5 inches of water including a foot of snow.

The Feb.21-24 Pineapple Express storm elevated the freezing level possibly as high as 5000 feet on the 22nd. The storm snow was drifted by moderate southeast winds.

The snowpack at Thompson Pass is isothermic, mostly rotten topped with a foot of fresh snow.

Check out the detailed observations <here>.

WEATHER:   Expect temperatures to cool slightly to the high twenties Fahrenheit during the day and low twenties in the late evenings.  The winds are forecasted to remain light until Wednesday afternoon, and we should enjoy some visibility in the next couple of days.  No additional precipitation is expected until this weekend.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/23 AM
 Thompson Pass – 2/24 AM
 Current Snow Depth  18″  45″
24 Hour Snow / Water Equiv. 2″ / 0.6″
3″ / 0.3″
Storm Snow / Water: 2/21-23 3″ / 3.8″ 12″ / 3.6″
February Snow / Water Equiv. 5.6″ / 4.5″ 37″ / 5″
Total Winter Snowfall / Water Equiv.
82″ / 15.1″ 242″ / 26.3″
Snowload in Valdez 20.8 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

Monday-Thursday, February 23-26, 2015


MONDAY TUESDAY WEDNESDAY & THURSDAY
high icon         
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: HIGH danger due to continued rain and storm snow.
  • Mid Elevations: HIGH danger to continued rain and storm snow.
  • Below treeline:  HIGH danger to continued rain and storm snow.

DANGER TREND:  The danger remains steady as warm temperatures and precipitation continues impact our region.

AVALANCHE FORECASTER CONFIDENCE:   Fair ; limited observations at higher elevations.

AVALANCHE PROBLEMS:  

Storm Snow Slab Avalanches -   Above 3500′ with heavy precipitation and moderate winds building slab.

icon-wet avalanches

Wet Slab and Wet Loose Avalanches – should be expected where temperatures are above freezing, especially in lower elevations where the snowpack is isothermic and less cohesive.

List of Avalanche Problems <here>

 

TRAVEL ADVISORY:   Steer clear of avalanche terrain today and make sure you are not spending time below potential avalanche paths. Avalanches releasing in dryer snow at higher elevations can entrain wet snow in the track, dramatically increasing the size and destructive potential. After two days of constant loading, more snow and rain will continue to stress the snowpack into this evening. More large natural activity is likely and human triggered avalanches are very likely (see Avalanche Activity below). DOT will be implementing more control work throughout the corridor today, so expect short delays.

NOTICE:  Through late March, please avoid traveling above and in close vicinity to the work crew disassembling transmission towers between mileposts 27 and 30. Keep an eye out for buried parts and cables.

AVALANCHE ACTIVITY:   

Feb. 22: Natural and artificial triggered avalanches to size D3 along the Thompson Pass corridor from the Port to Milepost 50.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:   Since late Friday night, the last 48 hours brought a constant onslaught of precipitation and warm weather to our region. When everything is all said and done, likely late tonight, over 3 inches of water (rain or snow) will have fallen. This warm weather elevated the freezing level as high as 3500 feet at times, but it is currently snowing at sea level this Monday morning. On Sunday morning, 6 inches of snow with 1.5 inches of water was measured on Thompson Pass. The Thompson Pass gap had rain throughout the day Sunday, but it flipped to snow in the early evening and has been accumulating all night. It is very possible that 3 feet of new snow has accumulated in the uppper elevations above the freezing level since this storm set in.

Expect to see fresh snow blanketing saturated old surfaces with runnels and percolation columns penetrating deeper into the snowpack. This wet snow pack will surely harden into a firm crust once the temperatures start to drop Tuesday.

Snow pit tests previously showed failure under the two crusts that formed in the last rain event Feb 16; further testing indicates these layers are gaining strength and bonding with continued moderate temperatures and increased load.

Check out the detailed observations <here>.

WEATHER:   Temperatures cooled last night bringing snow back to town replacing the rain. Temperatures will rise again today into the upper 30’s in town and low 30’s on Thompson Pass. Until the storm dissipates, expect more precipitation Monday evening.  Winds will be light to moderate on Thompson Pass from the southeast. Early Tuesday temperatures will begin to cool.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/23 AM
 Thompson Pass – 2/23 AM
 Current Snow Depth  18″  45″
24 Hour Snow / Water Equiv. 2″ / 0.6″
9″ / 1.8″
Storm Snow / Water: 2/21-23 3″ / 3.8″ 12″ / 3.3″
February Snow / Water Equiv. 5.6″ / 4.5″ 34″ / 4.7″
Total Winter Snowfall / Water Equiv.
82″ / 15.1″ 239″ / 26″
Snowload in Valdez 22 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

Sunday – Wednesday, February 22-25, 2015

SUNDAY MONDAY TUESDAY & WEDNESDAY
high icon high icon         
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: HIGH danger due to intense rain and storm snow.
  • Mid Elevations: HIGH danger to intense rain and storm snow.
  • Below treeline:  HIGH danger to intense rain and storm snow.

DANGER TREND:  The danger is steady as the onslaught of the atmospheric torrent continues to deliver a wintry mix of precipitation.

AVALANCHE FORECASTER CONFIDENCE:   Fair ; limited observations at higher elevations.

AVALANCHE PROBLEMS:  

Storm Snow Slab Avalanches -   Above 3500′ with heavy precipitation and moderate winds building slab.

icon-wet avalanches

Wet Slab and Wet Loose Avalanches – should be expected where temperatures are above freezing, especially in lower elevations where the snowpack is isothermic and less cohesive.

List of Avalanche Problems <here>

TRAVEL ADVISORY:   It is said that strange weather brings strange avalanches. While the quantity of precipitation is not unusual for the Chugach, the freezing level has been significantly elevated to 3500′ during this storm. With the added weight of new snow up high and rain below, avalanche activity should be expected by backcountry users. Its best to avoid all avalanche terrain and avalanche run-outs during high danger. Now is not the time to test your limits in the mountain environment.

NOTICE:  Through late March, please avoid traveling above and in close vicinity to the work crew disassembling transmission towers between mileposts 27 and 30. Keep an eye out for buried parts and cables.

AVALANCHE ACTIVITY:    February 19-20 allowed for some upper elevation observation. Lower elevations had widespread wet loose activity in the steeps. Mid-upper elevations had some loose slides to size D2 out of steep rocky terrain due to warming and solar radiation in the afternoon. A few pockets of windslab released naturally sometime during or after the Feb.13-16 storm, mostly off of steep cross-loaded gully walls.

Feb 19: Extensive wet, loose activity off south facing aspects with warm temps and sun; Significant slide reported in Sheep creek canyon off SW wall.

Feb 17: A long wet loose slide was heard in Mineral Creek off SW aspect; A small D1.5 was observed off a steep slope on Catcher’s Mitt.  No other slides were seen when checking the usual suspects with good visibility.

Feb 16: Wet loose slide debris was reported in Keystone Canyon coming off of steep slopes.  No other observations could be made due to the lack of visibility.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:   In the last twenty-four hours the atmospheric torrent delivered rain at sea level.  At Thompson Pass, mixed precipitation delivered 6 inches of snow with 1.5 inches of water. As much as 2 feet of snow has accumulated above the freezing level estimated at 3500 feet.

Surface snow throughout Thompson Pass is saturated and water is penetrating deeper into the snowpack. Snow pit tests previously showed failure under the two crusts that formed in the last rain event Feb 16; further testing indicates these layers are gaining strength and bonding. With continued moderate temperatures and increased load, these may not be a concern for long.

Avalanches releasing in dryer snow at higher elevations can entrain wet snow in the track, dramatically increasing the size and destructive potential.

Check out the detailed observations <here>.

WEATHER:   After a deluge of rain in the last 24 hours, its estimated we are half way through this storm. Two inches of water have fallen across the region, and another two inches of precipitation is in the forecast for Sunday through Monday. In low elevations you can expect a continued slushy mess. Higher up, two more feet of snow is possible before the storm abates. Temperatures and freezing levels remain elevated. Highs in the mid-30’s in Valdez and Thompson Pass. Temperatures are not expected to drop below freezing until Tuesday morning. Southeasterly winds from 15-25mph are expected through Thompson Pass with the passage of the storm.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/22 AM
 Thompson Pass – 2/22 AM
 Current Snow Depth  18″  37″
24 Hour Snow / Water Equiv. 1.4″ / 0.6″
5″ / 1.4″
Storm Snow / Water: 2/21-22 1.4″ / 0.6″ 6″ / 1.5″
February Snow / Water Equiv. 3.6″ / .75″ 25″ / 2.9″
Total Winter Snowfall / Water Equiv.
79.9″ / 11.25″ 230″ / 24.2″
Snowload in Valdez 22 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

Saturday-Tuesday, February 21-24, 2015

SATURDAY SUNDAY MONday & TUESDAY
high icon          
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: CONSIDERABLE danger rising to HIGH danger due to intense rain and storm snow.
  • Mid Elevations: CONSIDERABLE danger rising to HIGH danger to intense rain and storm snow.
  • Below treeline: CONSIDERABLE danger rising to HIGH danger to intense rain and storm snow.

DANGER TREND:  The danger is quickly increasing as an atmospheric torrent of weather just hit our region.

AVALANCHE FORECASTER CONFIDENCE:   Fair, as conditions will change quickly with this dramatic weather event.

AVALANCHE PROBLEMS:  

Storm Snow Slab Avalanches -   Intense rain and wet snowfall will quickly create slabs sitting on a dry, weak layer of new snow from Wednesday night.

icon-wet avalanches

Wet Slab and Wet Loose Avalanches – With above freezing temperatures rising up to 2300 feet and continuous rain/snow to fall, expect wet loose activity in the steeps and wet slab re-activity this weekend.

List of Avalanche Problems <here>

TRAVEL ADVISORY:   If you venture out into the elements today, have a plan and know the area, for visibility will be poor and conditions will quickly deteriorate as heavy snow and rain continues to fall throughout the day. Continuous monitoring of the conditions and conservative terrain selection will be crucial. As the snow forms a storm slab, recall that these can easily be triggered on convex terrain roll-overs. Steer clear of avalanche path runouts, for natural activity is possible.

Opportunity to learn more about avalanche safety: Saturday February 21 PWSCC Sugar Loaf Training room 10am-noon, Avalanche Skills Refresher. 1-5pm
Afternoon tour at Solomon. If you are new to touring or getting out to enjoy mountains in winter, join us for introductory safety skills. If you own beacon, probe, and shovel, bring them. We’ll have some loaners if you need to borrow. Call Valdez Parks and Rec to sign-up 835.2531. This is a Healthier You event – come get some more points!

NOTICE:  Through late March, please avoid traveling above and in close vicinity to the work crew disassembling transmission towers between mileposts 27 and 30. Keep an eye out for buried parts and cables.

AVALANCHE ACTIVITY:    February 19-20 allowed for some upper elevation observation. Lower elevations had widespread wet loose activity in the steeps. Mid-upper elevations had some loose slides to size D2 out of steep rocky terrain due to warming and solar radiation in the afternoon. A few pockets of windslab released naturally sometime during or after the Feb.13-16 storm, mostly off of steep cross-loaded gully walls.

Feb 19: Extensive wet, loose activity off south facing aspects with warm temps and sun; Significant slide reported in Sheep creek canyon off SW wall.

Feb 17: A long wet loose slide was heard in Mineral Creek off SW aspect; A small D1.5 was observed off a steep slope on Catcher’s Mitt.  No other slides were seen when checking the usual suspects with good visibility.

Feb 16: Wet loose slide debris was reported in Keystone Canyon coming off of steep slopes.  No other observations could be made due to the lack of visibility.

Feb 13:  Large D2.5 wind slab crown seen across valley on south-southwest face of peak west of 3 Pigs near Milepost 39. Small D1.5 crown seen in Gully 2. Both likely failed after loaded from the strong NE wind event last weekend.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:   Good quality snow, left over from the Feb 13-16 storm, has been found above 3000′ the last couple days. Loveland, North Odyssey Vertigo had groups lapping.

February 20th snowpack evaluation at 4100 feet in Vertigo demonstrated that even though two upper layer density change interfaces were reactive to testing, neither was easily triggered nor likely to propagate the fracture on a quality 2 surface.

Lower down below 3100 feet,  up to two crusts have formed that have some responsiveness to testing above and below them, but involve non-uniform, bad quality, break failures.

Moderate temperatures have strengthened the snowpack overall, but some sensitivity exists in the weaker layers just above and below the crusts. Pooling of water at older, firm interfaces has been present and may continue as more rain will hit our forecast region.

Windslab is likely found on all upper elevation aspects due to the onshore southerlies during the storm and outflow northeasterlies. The wind slab is deeper and more prevalent near the Pass and areas where wind is channeled. With continued warm temperatures, windslabs are bonding to underlying layers. Avoid actively loading slopes, as these will be the most sensitive to human-trigger.

Inland of Milepost 46 – less rain and snow fell. Invesitigate how the previously weak, faceted snow is evolving with the warmer temperatures and rain. Use small slopes to learn more about snow stability.

Check out the detailed observations <here>.

WEATHER:   Even though the south-southeast winds won’t be incredibly strong (maxing out in the 20’s) today, heavy snow on Thompson Pass and rain in the maritime began at 3 AM this morning and will persist throughout the duration of the day. Heavy precipitation rates will continue through Sunday and start to let up early Monday. By the end of this storm, 3 inches of water may leave a few feet of snow at the higher elevations. Expect temperatures in the low 40’s in town and Thompson Pass to possibly surpass freezing (32 deg) as the snow line rises today and even gets warmer Sunday.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/21 AM
 Thompson Pass – 2/19 AM
 Current Snow Depth  17″  39″
24 Hour Snow / Water Equiv. 0″ / ?″
3″ / 0.2″
Storm Snow / Water: 2/18-19 0″ / ?″ 3″ / 0.2″
February Snow / Water Equiv. 2.2″ / .15″ 19″ / 1.4″
Total Winter Snowfall / Water Equiv.
78.5″ / 10.65″ 224″ / 22.7″
Snowload in Valdez 22 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

Friday-Monday, February 20-23, 2015

FRIDAY SATURDAY SUNday & MONDAY
         
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: MODERATE danger due to windslab.
  • Mid Elevations: MODERATE danger due to windslab.
  • Below treeline: MODERATE danger due to above freezing temperatures.

DANGER TREND:  The danger is steady Friday, but will elevate Saturday with incoming storm.

AVALANCHE FORECASTER CONFIDENCE:   Good  Limited observations at higher elevations since the addition of February 13-16 storm snow.

AVALANCHE PROBLEMS:  

Wind-Slab icon

Wind Slab Avalanches -   Light northeast wind switching to the southeast; building fresh pockets of wind slab with the upper elevation dry snow.

icon-wet avalanches

Wet Slab and Wet Loose Avalanches – With above freezing temperatures rising up to 2000 feet and more significant rain/snow to arrive, expect wet loose activity in the steeps and wet slab re-activity over the weekend.

List of Avalanche Problems <here>

TRAVEL ADVISORY:   Conditions are incredibly variable out there with a thin layer of light, dry snow on top from Wednesday night. Closer to the port, breakable crust exists down low. Above 3000 feet it transitions to all dry snow without new crusts. Upper elevations near Moonlight Basin missed most of the rain and wind due to the track of the storm. Consider wet activity down low due to consistent above freezing temperatures, then as you climb higher, investigate windslab formation and reactivity.

Opportunity to learn more about avalanche safety: Saturday February 21 PWSCC Sugar Loaf Training room 10am-noon, Avalanche Skills Refresher. 1-5pm
Afternoon tour at Solomon. If you are new to touring or getting out to enjoy mountains in winter, join us for introductory safety skills. If you own beacon, probe, and shovel, bring them. We’ll have some loaners if you need to borrow. Call Valdez Parks and Rec to sign-up 835.2531. This is a Healthier You event – come get some more points!

NOTICE:  Through late March, please avoid traveling above and in close vicinity to the work crew disassembling transmission towers between mileposts 27 and 30. Keep an eye out for buried parts and cables.

AVALANCHE ACTIVITY:    February 19 allowed for some upper elevation observation. Lower elevations had widespread wet loose activity in the steeps. Mid-upper elevations had some loose slides to size D2 out of steep rocky terrain due to warming and solar radiation in the afternoon. A few pockets of windslab released naturally sometime during or after the Feb.13-16 storm, mostly off of steep cross-loaded gully walls.

Feb 19: Extensive wet, loose activity off south facing aspects with warm temps and sun; Significant slide reported in Sheep creek canyon off SW wall.

Feb 17: A long wet loose slide was heard in Mineral Creek off SW aspect; A small D1.5 was observed off a steep slope on Catcher’s Mitt.  No other slides were seen when checking the usual suspects with good visibility.

Feb 16: Wet loose slide debris was reported in Keystone Canyon coming off of steep slopes.  No other observations could be made due to the lack of visibility.

Feb 13:  Large D2.5 wind slab crown seen across valley on south-southwest face of peak west of 3 Pigs near Milepost 39. Small D1.5 crown seen in Gully 2. Both likely failed after loaded from the strong NE wind event last weekend.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:   February 19 recreationalists found good quality snow above 3000′ in the Pass corridor. Loveland and Vertigo had groups lapping. No obvious instabilities reported or observed.

February 13-16’s storm dumped 1-2 feet of heavy, wet snow at Thompson Pass. Limited observations have found the storm snow settling with up to two crusts formed below 3500′. Moderate temperatures have strengthened the snowpack overall, but some sensitivity exists in the weaker layers just above and below the crusts. Pooling of water at older, firm interfaces has been present and may continue as more rain will hit our forecast region.

Windslab is likely found on all upper elevation aspects due to the onshore southerlies during the storm and outflow northeasterlies. The wind slab is deeper and more prevalent near the Pass and areas where wind is channeled. With continued warm temperatures, windslabs are bonding to underlying layers. Avoid actively loading slopes, as these will be the most sensitive to human-trigger.

Inland of ~MP46 less rain and snow fell. Invesitigate how the previously weak, faceted snow is evolving with the warmer temperatures and rain. Use small slopes to learn more about snow stability.

Check out the detailed observations <here>.

WEATHER:   Despite a brief break in the clouds last evening, clouds have moved back in and kept the temperatures above freezing in the maritime zone.  Expect temperatures to rise near 40 again in town, and possibly reaching the low 30’s on Thompson Pass. Winds will be light and shift from the northeast to the southeast with the upcoming front that will arrive late Friday night and bring up to 3 inches of water with increasing temperatures by Sunday.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/20 AM
 Thompson Pass – 2/19 AM
 Current Snow Depth  17″  39″
24 Hour Snow / Water Equiv. 0″ / ?″
3″ / 0.2″
Storm Snow / Water: 2/18-19 0″ / ?″ 3″ / 0.2″
February Snow / Water Equiv. 2.2″ / .15″ 19″ / 1.4″
Total Winter Snowfall / Water Equiv.
78.5″ / 10.65″ 224″ / 22.7″
Snowload in Valdez 22 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

February 19-22, 2015

THURSDAY FRIDAY Saturday & SUNDAY
         
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: MODERATE danger.
  • Mid Elevations: MODERATE danger.
  • Below treeline: MODERATE danger.

DANGER TREND:  The danger is steady.

AVALANCHE FORECASTER CONFIDENCE:   Fair  Limited observations at higher elevations since the addition of February 13-16 storm snow.

AVALANCHE PROBLEMS:  

Wind-Slab icon

Wind Slab Avalanches -   Northeast wind is building fresh pockets of wind slab to two feet deep.

icon-wet avalanches

Wet Slab and Wet Loose Avalanches – Rain below 2500′ is wetting what snow there is, expect wet loose activity in the steeps. With rain line bouncing between 2000-3500′ the new snow is moist, wet slab to two feet deep could be human-triggered.

List of Avalanche Problems <here>

TRAVEL ADVISORY:   Make a travel plan that gives options for avoiding unstable snow. Heavy windslab will be found in gullies and low pockets. If the snow gets stiffer, sounds like styrofoam, or whumphs, choose another route that avoids the windloaded area.

Ride lower angle slopes to get a feel for conditions. As you get higher, re-assess how the storm snow is bonded – is there a slab? How deep? Does it fall off the old surface?

NOTICE:  Through March, please avoid traveling above and in close vicinity to the work crew disassembling transmission towers between mileposts 27 and 30. Keep an eye out for buried parts and cables.

AVALANCHE ACTIVITY:     Limited observations since last storm due to obscured visibility. Expect steeps >40 degrees to release wet loose in lower elevations.

Feb 17: A small D1.5 was observed off a steep slope on Catcher’s Mitt.  No other slides were seen when checking the usual suspects with good visibility.

Feb 16: Wet loose slide debris was reported in Keystone Canyon coming off of steep slopes.  No other observations could be made due to the lack of visibility.

Feb 13:  Large D2.5 wind slab crown seen across valley on south-southwest face of peak west of 3 Pigs near Milepost 39. Small D1.5 crown seen in Gully 2. Both likely failed after loaded from the strong NE wind event last weekend.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:   February 13-16’s storm dumped 1-2 feet of heavy, wet snow at Thompson Pass. Limited observations have found the storm snow settling with a crust or two formed below 3500′. Moderate temperatures have strengthened the snowpack overall. Much of the weak snow (present at the surface pre-storm) was melted or crushed. Wet slab is possible due to the pooling of water at older interfaces.

Windslab is found on all aspects due to the onshore southerlies during the storm and outflow northeasterlies since. The wind slab is deeper and more prevalent near the Pass and areas where wind is channeled. With continued warm temperatures older windslabs are expected to bond. Watch actively loading slopes, as these will be the most sensitive to human-trigger.

Inland of ~MP46 less rain and snow fell. Look for residual faceted snow – if it exists, use small slopes to learn more about snow stability.

Check out the detailed observations <here>.

WEATHER:   A new storm will arrive Friday night or Saturday morning. Models show 3″ of water equivalent possible. Temperatures will be warm and rise Sunday as the storm peaks, high 30s in Valdez, near freezing at Thompson Pass. South wind will be associated with the storm. When the storm passes, temperature is forecast to drop dramatically.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/18 AM
 Thompson Pass – 2/19 AM
 Current Snow Depth  18″  39″
24 Hour Snow / Water Equiv. 0″ / ?″
3″ / 0.2″
Storm Snow / Water: 2/18-19 0″ / ?″ 3″ / 0.2″
February Snow / Water Equiv. 2.2″ / .15″ 19″ / 1.4″
Total Winter Snowfall / Water Equiv.
78.5″ / 10.65″ 224″ / 22.7″
Snowload in Valdez 22 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours

Wednesday- Friday, February 18-21, 2015

WEDNESDAY ThurSDAY FRIDAY & Saturday
         
DANGER SCALE
  • mountain icon with elevationsUpper Elevations: CONSIDERABLE danger.
  • Mid Elevations: CONSIDERABLE danger.
  • Below treeline: CONSIDERABLE danger.

 

DANGER TREND:  The danger is decreasing.

AVALANCHE FORECASTER CONFIDENCE:   Fair:      Limited observations at higher elevations since the addition of recent storm snow.

AVALANCHE PROBLEMS:  

Storm Snow Avalanches -   With a freezing level hovering somewhere above Thompson Pass, it is estimated between one and two feet of snow has accumulated above 4000 feet elevation.

Wind-Slab icon

Wind Slab Avalanches -   The new snow has been drifted by strong southerly and south easterly winds.

 

 

List of Avalanche Problems <here>

TRAVEL ADVISORY:      Rain and wind both affected the new snow during the storm. We found that the snowpack was consistently inconsistent across very small distances. Assuming the storm snow has not bonded yet to the underlying slab, an external trigger could be all that is needed.  Be conservative in avalanche terrain, this includes the run out zones of bigger avalanche paths. Look up, look down, look all around.

NOTICE:  Through March, please avoid traveling above and in close vicinity to the work crew disassembling transmission towers between mileposts 27 and 30. Keep and eye out for buried parts and cables as the snow falls. Use caution while driving.

AVALANCHE ACTIVITY:     

Feb 17: A small D1.5 was observed off a steep slope on Catcher’s Mitt.  No other slides were seen when checking the usual suspects with good visibility.

Feb 16: Wet loose slide debris was reported in Keystone Canyon coming off of steep slopes.  No other observations could be made due to the lack of visibility.

Feb 13:  Large D2.5 wind slab crown seen across valley on south-southwest face of peak west of 3 Pigs near Milepost 39. Small D1.5 crown seen in Gully 2. Both likely failed after loaded from the strong NE wind event last weekend.

Avalanche sizing using the destructive scale <here>

Avalanche size estimation aid <here>.

SNOWPACK DISCUSSION:        The last storm brought in heavy, wet snow- the kind that soaks your gloves in a second but is just right for making great snowballs. Pinwheels or “death cookies” can be observed in lower elevations which are surface clues to wet snow. Due to the high freezing levels, Monica and I observed that much of the snow through Thompson Pass is moist but not yet frozen, and is surprisingly soft. In cooler areas, a rain crust is detectable up to 3500ft. Overall, this last blast of precipitation will have a stabilizing effect- adding cohesion within the snowpack as well as increasing the snow depth. We expect to see the weaker layers from earlier in the season become less reactive in snow pit tests. However, wind transport during the storm may have created soft slabs in areas loaded from the southeast. There is still uncertainty in how this slab has bonded as poor visibility precluded access to higher elevations yesterday.

Check out the detailed observations <here>.

WEATHER:         Temperatures jumped up in the last couple days causing roofs to shed, ice to melt, and Valdez residence to reach past their snowboots for their x-tra tuffs.  One to two feet of new snow was distributed through Thompson Pass. This year snow has stacked up slowly but in this part of Alaska it’s too early to call this winter a loss. Looking into the future, synoptic weather charts show another large low pressure system working towards southcentral Alaska that is due to arrive by the weekend. Until then, we’ll enjoy unseasonably pleasant February temperatures that will hover around freezing. Winds are forecasted to be light in the region but occasionally moderate through Thompson Pass. Fog may reduce visibility during this time, although cooler areas such as higher elevations or further “up-country” will be less affected.

Use links below to follow the up and coming weather.

SNOW HISTORY:
Valdez – 2/18 AM
 Thompson Pass – 2/18 AM
 Current Snow Depth  18″  37″
24 Hour Snow / Water Equiv. 0″ / ?″
0″ / 0″
Storm Snow / Water: 2/16-? 0″ / ?″ 4″ / 0.9″
February Snow / Water Equiv. 2.2″ / .15″ 16″ / 1.2″
Total Winter Snowfall / Water Equiv.
78.5″ / 10.65″ 221″ / 22.5″
Snowload in Valdez 21 lbs / square foot
SNOW DEPTH & WATER SURVEY January 28, 2015 Depth Snow Water Equivalent
Milepost 2.5 Valdez  31″  7.1″
Milepost 18 36″
7.4″
Milepost 29 Worthington Flats 54″ 11.6″
Milepost 37 Tsaina River bridge 40″ 5.9″

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <here>.
  • Further weather resources <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:
  • Upper Elevations: Alpine – Above 2,000 feet
  • Mid Elevations: Treeline ~ 2,000 feet
  • Lower Elevations: Below treeline – Below 2,000 feet

Run map of some of the forecast area <here> NEWS: 

  • Develop snow analysis skills at the Avalanche Level 2 March 6-9, 2015.
  • Our region is “one of the snowiest places on earth” says the recent weather detective climatologist investigation into the Serendipity / Rendezvous snowfall record set in 1963 <here>.

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

This forecast expires after 24 hours