Valdez

Forecast Expired - 02/21/2022

Above 3,000ftConsiderable

1,500 to 3,000ftConsiderable

Below 1,500ftConsiderable

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Deep Slab:

 

D3 hard slab avalanche on Billy Mitchell ~4000’/ North aspect

 

A very uncommon and dangerous snowpack exists in the Valdez/ Thompson Pass region.  Very large human triggered avalanches are likely.  Conservative terrain choices will be necessary today.

 

Very large and unusual avalanche patterns have been observed that failed during the 2/17-18 time period.  Most of the activity noted was deep hard slab avalanches that failed near the ground and involved the entire snowpack.  This setup does not heal itself overnight.

 

We currently have two persistent weak layers that we are dealing with.  There is the 1/24 facet crust combo buried 3-5 feet deep, and the November facets near the base of the snowpack 7+ feet deep.  Both have been reactive in the last 48 hours.  The November facets that we have been talking about the entire season are currently our main concern.  These have been under a lot of stress with the near continuous snowfall we have received over the last month.  In the last month Valdez has received precipitation equaling 13.14″ of Snow water equivalent.  

 

The November facets have reached the tipping point and very large natural avalanches have occurred in the past 48 hours.  The avalanche patterns we are seeing are unusual in their depth, size and location.  Deep hard slab avalanches have been observed on small 30° rolls, or areas that would normally be considered conservative terrain.  This creates a very dangerous scenario where areas that people typically recreate in could produce deadly hard slab avalanches that involve the entire snowpack.  Patience is recommended.  The only effective way to manage a deep persistent problem is to employ safe travel protocols such as: only exposing one person at a time to avalanche prone slopes, avoiding terrain traps and maintaining good communication.  Tracks are not a sign of stability with this problem, avalanches can occur even after many tracks have been laid down.

 

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Wind Slab:

Although winds have been light, there is a possibility that you may encounter fresh wind slabs in isolated areas.  These could be reactive to human triggers, but will most likely be small.  The most likely areas to encounter this problem will be on the lee side of high elevation ridges that are exposed to north wind.  Flagging ridges and peaks will be an indicator that wind slabs are forming and do exist.  On 2/19, flagging peaks and ridges were not observed nor was wind affected snow below 4000′.   Small wind slabs may have enough force to step down to the persistent weak layers that are underneath (see problem 1).  Human triggered avalanches that do occur, will likely fail at faceted snow deep within our snowpack creating deadly avalanches.    

 

 

 

 

 

 

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 3

Wet Avalanches:

Wet loose avalanches will be possible today in steep lower elevations on solar aspects.  wet loose avalanches have the potential to knock you off your feet and carry a person or machine downhill.  Pay attention to what is above and below you and what the consequences would be should you be knocked off of your feet and carried downhill.

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

2/17-18-  A Significant avalanche cycle occurred during this time period.  Most of the activity failed on deep persistent weak layers.  These were the 1/24 facet-crust combo and the November facets.  Numerous hard slab avalanches were observed that failed near the ground.

Deep hard slab activity included: Billy Mitchell, Happiness, 40.5 Mile Peak, NE Crudbusters Multiple spots around the Tonsina Glacier, West side of Iguana backs (really wrong place), Multiple spots in the Tsaina valley, Girl Mountain, Cracked Ice, Python, Buttress west of Nicks (this is has slid multiple times this year), North Oddessey shoulder.  This is only a portion of the activity that occured.  

Most of the activity occured around 4000′, although there were outliers at upper elevations.

 

Billy Mitchell

 

 

Iguana Backs (Really Wrong Place)

Girls

Python

Cracked Ice

Tonsina Glacier

 

North Oddessey Shoulder

 

2/17 – Keystone Canyon was reported to have many size 1-2 loose avalanches on the steep canyon walls.  Crowns with depths of 10-15″ have been reported as well on the ice climbs Simple twist, Bridal Veil and Green Steps.  Photo approach to Simple Twist

2/15- A large deep persistent avalanche occurred on “Back It In” near Mt Dimond.  The trigger is unknown, but was most likely triggered remotely by a helicopter landing on a recon mission.  It appears that a cornice fall triggered a shallow slab over rocks which then stepped down creating a deep slab ~500 feet wide that entrained the entire snowpack.  Several other deep slabs failed sympathetically below.

2/13 – Meteorite ramp was reported to have released full path failing at the bedrock.

2/9 & 2/10- Numerous natural avalanches occurred during this time period.  

Mt tiekel (50 mile) and 38 mile ran naturally, with 38 mile depositing a small amount of debris on the road.  

 The entire Python Buttress failed naturally close to the ground with a crown line approximately 1/4 mile in length. Numerous avalanches in the gully to the east occured as well.  Debris from both areas extended ~200 meters across flat terrain.  

 Gully 2 and Nicks had significant slides run into their fans.

 Snowslide Gulch ran naturally and hit the road.  

DOT mitigation efforts produced activity at Three Pigs and Snowslide Gulch.

Natural activity was more extensive than noted.  Snowfall continued after the event refilling crowns and preventing a good look at the extent of natural activity.

1/30-Several natural persistent slab avalanches were observed in the intermountain and continental zone.  

  • Remote snowmachine triggered avalanche on Little Girls/ SE aspect/~3500′.   Member of group reported that 2 members of a larger party were waiting on the lower angle ridges (bro bowl up route) below the slide pictured waiting for the rest of a larger group.  Rider 2 went to play on a small hill nearby when rider 1 felt a large collapse and the slides pictured came down.  The rest of the group gathered up and about 5 minutes after the remote trigger felt an earthshaking collapse that had alders swaying and group reported the feeling of dropping/settling a vertical foot.  A noise that was described as a bomb quickly followed.  The group left the area immediately and did not observe any further avalanche activity caused by the collapse.  Other collapses were noted later in the day.
  • Natural avalanche on the Little Matterhorn buttress/ North/ ~3500′.  This avalanches’ width implies that it was more than a wind slab avalanche and failed on a persistent weak layer.  The interesting thing was how wide this avalanche was, and that the depth was much shallower than other persistent slabs that have been noted.  The takeaway point is that our area has a lot of spatial variability, meaning that dangerous facets snow may be buried deep in some areas making it very difficult to affect.  And in other areas weak faceted snow from November exists close to the surface in some locations, making it easier to affect.  Use caution in steep areas with thin snowpack.
  • Natural D3 persistent slab avalanche Area 51/ North, east, and west aspects/ ~3500
  • Natural D3 persistent slab avalanche Pt 6153 just north of Averys/ ~5500′

Natural D3 Persistent slab avalanche/ Shovel/ northeast aspect/~5000′.

South aspect hogback ridge/~3000′

Snoopys/East aspect/~4000′

1/29- Observed numerous D2 avalanches on Billy Mitchell (cry babies area) and one D3 on Happiness.  These were all northerly aspects.  On Billy, slides originated between 3-4000 feet and on Happiness ~5000′.

1/28- During brief break in the clouds, observed a Natural D3 avalanche on Catchers Mitt.  It is likely this slide failed on a persistent weak layer, as the crown was deep (3-4) feet and ran a considerable distance.

1/22-1/24- A D3 natural avalanche was observed on 1/22 in snow slide gulch that ran to just below the summer trail.  

On 1/26 2-D3 naturals were seen on the east face of Mt Tiekel (beyond forecast zone) that ran half way through their aprons.  These likely occured between the 1/22-1/24 time period.

Clouds prevented observation of where these slides originated

1/22-  Clouds made observing avalanche activity difficult, although numerous large wet loose slides were observed on south aspects of Town Mountain in the Port of Valdez.

1/13- Multiple large natural avalanches were noted following the snowfall on 1/13.  Most were near high elevation ridge lines, although mid elevation storm slabs were noted on north aspect of Catchers Mitt and south aspect of Mile high.  Other avalanche not shown in photos include Goodwills north aspect and Oddeyssey north aspect.

 

1/1-1/4-  The new years day wind event created an avalanche cycle that was difficult to document due to crowns being rapidly reloaded by 80 mph winds.  Below are photos of a couple very large slides that were still visible in the Hippie ridge area.  Naturals were also noted on Three Pigs, 40.5 Mile, Crudbusters, Python Buttress.

 

12/29-  Multiple natural wet loose D1-D2’s were observed in the Port of Valdez with no step downs noted.

12/23- Berlin Wall north face ~5000′ HS-N-R3-D2-O.  It is possible this occurred on 12/21, although it was not observed until 12/24.

12/21- Numerous natural avalanches observed all along the north side of Thompson Pass, as a result of strong NE wind event along with a couple inches of new snow and rising temperatures.  Observed naturals on all aspects except windward slopes with crowns originating from 1000 feet to 5500 feet in elevation.  Most of these were hard slab avalanches.  Crown depths were difficult to discern due to reloading, although some crowns looked to be up to 2 meters in depth.

12/19- D 2.5 natural avalanches were observed on the north facing buttress west of Gully 1 and Schoolbus.  

12/14-  Several natural avalanches were observed although poor visibility prevented a full view of the action.  The most notable natural was observed in Nicks Happy Valley on a NW aspect ~4000′.  Crown depth was not visible.  Debris ran down the valley and piled up at the typical snowmachine pickup.

12/8- Large remote trigger/ sympathetic avalanche event occurred 12/8 with avalanches extending from Gully 1 to Nicks.  Avalanches were soft slabs that ranged in size from D1-D3.  Over 10 separate avalanches were counted with crown depths averaging 2-3′.  One avalanche had a crown length of half a mile while another was triggered over a mile away from the point of collapse.  See observation section for full report and more photos.

12/7- Only a few natural avalanches were noted during the last storm.  It is likely there were more during the storm, but crowns may have been filled in by subsequent wind and snow.

D2’s on Town mountain was observed ~3000′

A couple of D2’s were noted in N. Oddessey gully and Big Oddessey.

D2 on 40.5 mile peak ~5500′.

12/2-12/3- Several natural D2 avalanches were noted on south aspects of Three pigs, Hippie Ridge and Averys.  These windslab avalanches originated between 4000-5500 feet elevation.

Weather

NWS Watches and Warnings

NONE
 
Point forecast for Thompson Pass
Today
Partly sunny, with a high near 19. Northeast wind 15 to 20 mph.
Tonight
A 20 percent chance of snow after 3am. Mostly cloudy, with a low around 13. North wind 10 to 15 mph decreasing to 5 to 10 mph after midnight.
Washington’s Birthday
Snow likely, mainly after 3pm. Mostly cloudy, with a high near 26. Southwest wind 5 to 10 mph. Chance of precipitation is 70%. New snow accumulation of less than one inch possible.
Monday Night
Snow. Low around 26. Southwest wind 10 to 15 mph becoming east after midnight. Chance of precipitation is 100%.
Tuesday
Snow, mainly before 3pm. The snow could be heavy at times. High near 29. South wind 10 to 15 mph. Chance of precipitation is 100%.
Tuesday Night
A 40 percent chance of snow before 3am. Mostly cloudy, with a low around 19. South wind 5 to 10 mph.
Wednesday
A 30 percent chance of snow after 3pm. Partly sunny, with a high near 29.
Wednesday Night
A chance of snow. Mostly cloudy, with a low around 21.
Detailed forecast for Thompson Pass Mid elevation (2000-4000 Feet)
DATE             SUNDAY 02/20            MONDAY 02/21            
TIME (LT)        06    12    18    00    06    12    18    00    06
CLOUD COVER      BK    BK    OV    BK    OV    OV    OV    OV    OV
CLOUD COVER (%)  65    50    75    55    70    85   100   100   100
TEMPERATURE      18    22    18    16    17    25    26    26    26
MAX/MIN TEMP                 22          15          26          26
WIND DIR         NE    NE    NE     E     S     S    SE    SE     S
WIND (MPH)       13    11     9     3     4     5    10    20    17
WIND GUST (MPH)                                            42      
PRECIP PROB (%)   0     5     5    20    40    70    90   100   100
PRECIP TYPE                         S     S     S     S     S     S
12 HOUR QPF                0.00        0.01        0.09        0.60
12 HOUR SNOW                0.0         0.0         0.7         7.2
SNOW LEVEL (KFT)0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.0   0.1
Snow and Temperature Measurements

 

Date: 02/20 24 hr snow  HN24W* High Temp Low Temp Weekly SWE (Monday- Sunday) February Snowfall Season Snowfall HS (Snowpack depth)
Valdez 0 0 35 12 3.15 73 231 76
Thompson Pass 0 0 31 19 3.7 95 352 75
46 Mile 0 0 37 12 N/O 32 120**  43

 

All snowfall measurements are expressed in inches and temperature in Fahrenheit. 24 hour sample period is from 6am-6am. 

* 24 hour snow water equivalent/ SWE.

** Season total snowfall measurements for 46 mile began December 1st.

 

Season history graphs for Thompson Pass

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Click on links below to see a clear and expanded view of above Season history graphs

 

TP WX Nov 21

 

TP wx Dec 21

 

TP Jan 22

 

TP as of 2/20

 

 

 

Additional Information

Winter weather began early this season, with valley locations receiving their first snowfall on the last day of Summer (September 21st).  Following this storm, above average temperatures and wet weather occurred from late September through early November.  During this time period Thompson Pass received 96 inches of  snowfall by November 7th and Valdez recorded 7.73″ of rain.  

After the 7th of November our region experienced a sharp weather pattern change.  Temperatures dropped below seasonal norms and snowfall became infrequent.  Between the time frame of November 7th- November 28th Thompson Pass only reported 19″ of snow with 1.1″ of Snow water equivalent (SWE).  Temperatures remained below 0° F for most of the period.   This cold/dry weather caused significant faceting of the snowpack, with poor structure the result.

Moderate snowfall returned to our area the last day of November and deposited 6-12 inches of new snow.  The amount varied depending upon the locations’ proximity to the coast.  As the storm exited on the 2nd of December it was quickly replaced by moderate to strong northeast winds.  

On 12/5-12/6 Valdez received 2 feet of new snow with Thompson Pass reporting 16″.  Blaring red flags like collapsing, shooting cracks and propagation in stability tests were immediately present.  On 12/8 a significant remote/ sympathetic avalanche event occurred from Gully 1 through Nick’s Happy Valley. 

Strong outflow winds began on 12/11 with periods of light snowfall.  This has caused slab thicknesses to become variable in areas exposed to NE winds.

A fair amount of natural avalanche activity occurred during the 12/11 wind event mostly on southerly aspects.  The week following this wind event fairly benign weather occurred which allowed the snowpack to adjust and for stability to improve although snowpack structure has remained poor.  

On 12/21 our area received a couple inches of snow along with temperatures rising and strong outflow winds.  This combination of weather kicked off a fairly significant natural avalanche cycle.  Many of the slabs appeared to be deeper wind slabs that were created from the 12/11 wind event.  These failed on faceted snow created in November.  The event is yet another indicator of our poor snowpack structure and its inability to receive any major change in weather without the avalanche hazard rising in conjunction.

 

On 12/26-28 warm air moved in at elevation and caused light rain to fall up to ~4000′.  A very thin rain crust was formed in many locations that was unable to support a persons weight.

 

A prolonged period of strong north winds began on new years day with wind speeds reaching 80 mph.   As winds tapered to 30-40 mph on the 5th temperatures plummeted with lows exceeding -30 F in the Tsaina valley.

 

Snowfall returned to our area on 1/13 with a foot of snow reported on Thompson Pass.  An additional ~6 inches of snow were received on 1/15 with settled storm totals of 2.5 feet above 5000′.  

Moderate outflow winds kicked up on 1/16, but were short-lived and not wide spread.  This was followed by two days of calm and mild weather.

 

Stormy weather returned to our area on 1/19 with 10 consecutive days of measurable precipitation.  The Initial change in weather brought ~1 foot of dry snow which was quickly followed by a big warmup from 1/21-1/24, with snow line rising to 3000′.  This caused the snowpack to go upside down at the surface which created a decent amount of natural wet/loose activity near sea level and a couple D3 slab avalanches on Snowslide Gulch and Mt.Tiekel.  Observation of avalanche activity was limited due to continued storms and crowns being filled back in.  

 

After 1/24, precipitation continued with temperatures slowly dropping and snow line returning to sea level.  Precipitation ended on 1/29 with moderate northeast winds building wind slabs as skies cleared.

 

Snow water equivalent storm totals for 1/19-1/28 are as follows:

Valdez: 6.73″

Thompson Pass: 4.3″ (1/19-1/26)

46 Mile: 1.93″

A period of moderate outflow winds directly followed as the late January storms cleared out.

1/30-2/3-  A period of mild weather occured with clearing skies dropping temperatures and light to moderate northerly winds.  A fair number of large natural persistent avalanches were observed that occured during the previous storm and as a result of outflow winds at the tail end of the storm.  First human triggered persistent slab avalanche since 12/8 reported on 1/30.  This was remotely triggered.

 

A parade of lows began on 2/4 with precipitation measured in Valdez for 9 consecutive days.  On 2/9-10 south winds ramped up to 50 mph and triggered a natural avalanche cycle with debris covering and closing the highway in a couple spots.  Numerous deep persistent slab avalanches were observed in the mid elevation band.  Storms continued after the natural cycle preventing a thorough record of the activity.

 

Following the 2/9-10 natural cycle storms continued to roll through our area with moderate to heavy accumulations occurring each day.  On the 17th a more significant system moved through bringing ~20 inches of snow to Valdez and Thompson Pass with 2″ of SWE.  This storm sparked a widespread natural avalanche cycle creating very large hard slab avalanches on all aspects, with many failing near the ground.  Even small 30° glacial rolls were reported failing down to black ice.  The November facets have been reactive this year every time there has been a major change in weather and this storm was no exception.

 

 

Announcements

The avalanche hazard is CONSIDERABLE at all elevations.  Very dangerous avalanche conditions continue to exist.  Very large human triggered avalanches are likely and natural avalanches are possible.  Human triggered avalanches have the potential to fail near the ground and involve the entire snowpack.   

Click the + Full Forecast button below for a list of current avalanche problems, travel advice, weather resources and more.

 

Help to improve your local avalanche center and contribute an observation to the website.  You can also contact me directly at [email protected] (907) 255-7690.