Forecast Expired - 02/12/2020

Above 4,000ftConsiderable

2,000 to 4,000ftConsiderable

Below 2,000ftConsiderable

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Wind Slab:


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


  • Historic
  • Very Large
  • Large
  • Small


  • Increasing
  • Steady
  • Decreasing

Problem 2

Persistent Slab:


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


  • Historic
  • Very Large
  • Large
  • Small


  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

2/10: Skies cleared yesterday, from 46 mile to Thompson Pass very few natural avalanches were seen from the 27 inches of snow that fell from 2/8- 2/10.

2/8: Many full path avalanches were reported running around Valdez glacier lake.

2/6: 2 remote triggered avalanches on RFS at 1800-2000′.

  • SS-ARr-R1-D1-O, N aspect, 60′ wide, 50 cm crown, 1800′, failed on buried near surface facets.
  • SS-ARr-R3-D1.5-O, N aspect, 100′ wide, ~60 cm crown, 2000′, failed on buried near surface facets.

Photo of 1st remote trigger listed

-Natural avalanches observed on south aspect at mile 40, ~1800′, 1-2 feet deep and ~100′ wide. SS-NL-R2-D1.5-O.  These were triggered by small snow sluffs.

2/2: Numerous Small pockets of unsupported terrain released naturally in the tsaina valley below 2000′, 2′ deep.

1/27-1/30: Naturals were observed on RFS, N aspect ~6000′,

Avalanches were also observed on -40.5 mile, ~5000′ ,W aspect, 60 m crown

– 2 paths on Three Pigs, ~5000′, SE aspect, ran into the top 1/3 of aprons.

– 3 slides on Billy Mitchell ranging from 3000′-6000′, NW- N aspect.  The most significant was on the upper bowl of cry babys, ~5000′, ~200 m crown, 1-2 meters deep.  

1/23- Found fresh debris in a gully off point 3848′ behind the airport.  D2, ran ~2000′.

~ 1/10- There have been several natural windslabs that have released in the Thompson Pass region:

-South slope of catchers mitt, near 27 mile icefall,~3500′, ~300m wide ,~3′ deep, ran 500′ HS-N-R3-D2.5.  Photo shows extent of crown, which may have been bigger and is now filled in by wind transported snow.

– Gully Between Little and Big Oddessey, NW, 4000′, ~60 M wide, ~2-4′ crown, ran 1000′

-Averys, ~4000′, SW, ~70 M wide, ran ~1000′

1/11- Two natural wind slab avalanches observed at moonlight basin, 2500′-2800′, S aspect.  

The first was on the small last roll before the road and had debris chunks up to 3′ deep “crown filled in by wind”, 200′ wide.

The second was in a cross loaded gully ~ 300′ above the road, with a crown up to ~10′ deep, ~100′ wide.




1/11-  Strong NE winds are forecasted for Thompson Pass and may diminish as the day goes on.

The Thompson Pass Mountain Forecast covers the mountains (above
1000 ft) surrounding Keystone Canyon through Thompson Pass to
Worthington Glacier.

This forecast is for use in snow safety activities and emergency

                   Today        Tonight

Temp at 1000`      26 F         18 F

Temp at 3000`      14 F         13 F

Chance of precip   0%           80%

Precip amount
(above 1000 FT)    0.00 in      0.10 in

Snow amount
(above 1000 FT)    0 in         1-2 in

Snow level         sea level    sea level

Wind 3000` ridges  NE 7-30 mph  NE 4-25 mph

  24h snowfall (inches) HN24W (inches)* Hi Temp (F) Low Temp (F) February snowfall Season Snowfall Snow height 
Valdez 1 .07 33 8 26 133 52
46 mile 0 0 30 6 10 71 25

Thompson Pass “DOT”

0 0 23 3 50 408 93

 HN24W= total water received last 24 hours in inches

Thompson Pass weather history 19/20 season beginning 12/21 through 1/23.  Click on links below to see full size image.



























TP Jan 2020

TP Feb 2020


Additional Information

Our area received 27 inches of snow 2/8-2/10.  This new snow is now being redistributed by strong NE winds.

Prolonged arctic temperatures in January have created a weak snowpack.  Weaknesses in our snowpack are pronounced at old rain crusts where moisture was once concentrated, and has now formed facets. These rain crusts exist up to 3000′.  Near surface facets were also formed in January and are spatially variable depending on their exposure to previous wind events.

Poor stability exists below 2500′ in the Thompson Pass region.  Crust/Facet combos and near surface facets up to 2 mm exists that are now buried under 2-3 feet of snow.  This layer is especially prominent in areas that were protected from strong wind in January and north of Thompson pass where temperatures were colder.

Prior to the 2/8 storm, stability improved as you go up in elevation and became good above 3000′.  Strong outflow wind events in January did not allow near surface facets to be preserved in most locations. A very strong layer of wind affected snow exists under 2-3 feet of snow that fell beginning on the 26th of January.  This wind affected snow is creating a bridging effect above a faceted mid and lower snowpack.  In alpine areas that were protected from January wind events persistent weak layers will be present in the mid snowpack that could still be reactive.  In alpine areas this problem layer will be difficult to assess its distribution.

There is a high degree of spatial variability in our area.  Careful snowpack assessment will necessary slope by slope.  If you find good stability in one area don’t assume that the next place you go will be the same.

Forecast Confidence is Moderate.

Resolution is low 


Near surface facets found at 3000′ on Billy Mitchell 1/19. 2 MM grid.

 There have been limited observations from interior locations due to low snow at lower elevations.   Use caution if you travel in these areas.

If you see something in the mountains that could contribute to this forecast, leave a public observation.  The more observations we receive, the better we can tune our forecast. If you would rather not post an observation publicly, feel free to send me an email at [email protected]

Be aware that the elevation bands have changed on our website.  Low is now below 2000′, Mid is 2000-4000′ and high is 4000′ and above. 

Send in your best mountain recreation photos to [email protected] so we can post a photo of the week!

Photo of the Week

Thanks to Spencer Byson for sending in this photo!


The avalanche hazard is considerable at all elevations.  North east winds began on the afternoon of 2/10 and reached speeds of 60 mph on Thompson Pass.  This is resulting in fresh wind slabs forming on lee aspect (SE-NW) that will be reactive to triggers today.  Watch out for pillowed snow surfaces, shooting cracks and sudden deepening of the new snow, these are all indicators that you have found fresh wind slab.  Human triggered avalanches are likely today in areas that have received recent wind loading.  Avoid areas that are receiving active loading, cross loaded gullies and terrain traps.