Forecast Expired - 12/05/2022

Above 4,000ftModerate

2,000 to 4,000ftLow

Below 2,000ftLow

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Wind Slab:

 Strong north winds occurred between 11/26-11/29 stripping snow surfaces down to old crusts and forming pencil hard wind slabs on lee aspects.   

Time has allowed wind slabs to lock up and gain strength.  It is unlikely at this point to trigger a wind slab avalanche below 4000′.  Above 4000′ temperatures have risen to at or above freezing over the last 24 hours.  This rise in temperatures creates the possibility that old wind slabs could reactivate.  This is not a very likely scenario as heat will take time to penetrate into deeper layers of the snowpack, but can not be ruled out as the consequences would be high.  A cold front is forecasted to move in on Monday, which will make wind slabs unlikely to trigger at all elevations.


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


  • Historic
  • Very Large
  • Large
  • Small


  • Increasing
  • Steady
  • Decreasing

Problem 2

Persistent Slab:

There are multiple rain crusts from October that are faceting in the mid and lower snowpack.  Recent winds have created very strong snow at the surface making it difficult for a person or machine to affect these deeper layers.  

 There is an inversion in place (higher temperatures at upper elevation).  Above freezing temperatures above 4000′ have slightly increased the likelihood for persistent slab avalanches to be triggered.  This avalanche problem would probably not show signs of instability and could have  significant consequences.  A cold front moving in on Monday will once again lock up persistent weak layers.

There is a higher possibility of affecting these layers in the continental zone where a more faceted snowpack exists.



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


  • Historic
  • Very Large
  • Large
  • Small


  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

11/14-  Debris from a D3 natural avalanche at snow slide gulch ended 100 vertical feet above the Lowe river.  

Large avalanches (D2-2.5)also occurred in multiple other locations including Berlin Wall, Catchers Mitt, South Three Pigs and Billy Mitchell.  The activity extends beyond this list, and mostly occurred during the peak of warming and precipitation on 11/13.

Multiple natural D1-1.5 avalanches were observed on multiple aspects at low elevation.  No step downs noted.

12/1-  2 D2.5 natural avalanches were noted on Three Pigs (Beaver slide, Pig Leg). Pig leg ran into the top 1/3 of the fan and Beaver Slide stopped near the end of its track.  These both likely occurred during the outflow wind event 11/26-11/29.

D2 natural wind slab was observed on 40.5 mile peak on a west aspect ~3000′.  Crown depth range estimated 1-2 feet and 200′ long


Check out our updated weather tab!  A collection of local weather stations are available for viewing with graphs and tabular data included.

NWS Watches and warnings


NWS Point forecast for Thompson Pass

Mostly sunny, with a high near 25. North wind around 5 mph becoming calm in the afternoon.
Mostly clear, with a low around 23. Southwest wind around 5 mph.
A 50 percent chance of snow after 3pm. Increasing clouds, with a high near 27. Southwest wind around 5 mph.
Monday Night
Snow likely. Mostly cloudy, with a low around 23. South wind 5 to 10 mph. Chance of precipitation is 70%.
Snow likely, mainly after noon. Mostly cloudy, with a high near 27. South wind around 5 mph. Chance of precipitation is 70%.
Tuesday Night
Snow. Low around 20. East wind 10 to 20 mph becoming northeast after midnight. Chance of precipitation is 80%.
Detailed forecast for Thompson Pass Mid elevation (2000-4000 Feet)

Date               Sunday 12/04/22         Monday 12/05/22         
Time (LT)          06    12    18    00    06    12    18    00    06
Cloud Cover        SC    SC    FW    CL    FW    BK    OV    OV    OV
Cloud Cover (%)    50    35    15     5    10    60    90    85    80
Temperature        20    25    25    23    22    24    26    26    24
Max/Min Temp                   26          22          27          23
Wind Dir           NE    SW    SW    SW    SW    SW     S     S     S
Wind (mph)          2     2     2     3     4     4     6     8     4
Wind Gust (mph)                                                      
Precip Prob (%)     0     0     0     0     0    10    70    70    50
Precip Type                                       S     S     S     S
12 Hour QPF                  0.00        0.00        0.04        0.21
12 Hour Snow                  0.0         0.0         0.2         2.4
Snow Level (kft)  1.6   1.5   1.3   0.6   0.3   0.2   1.2   1.2   0.9

Click on link below for Thompson Pass weather history graph:






24 hr snow HN24W* High temp Low temp 72 hour SWE* December snowfall Seasonal snowfall Snowpack Depth
Valdez 0 0 26 16 0 0 34 11
Thonpson pass  0 0 24 6 0 1 98 30
46 mile 0 0 13 3 0 1 1** 16



*HN24W- 24 hour Snow water equivalent in inches

*SWESnow water equivalent

**46 mile seasonal snowfall total begins December 1st.

Additional Information


Our snow season began with above average precipitation and temperatures.  Beginning in September, snow lines generally hung around 4500′ until 10/12.  At that point our area received the first snow down to sea level with 12-16 inches on the north side of Thompson Pass.  

On 10/15 wet conditions continued with the freezing line rising to 5000′ or higher. As skies finally cleared on 10/22 we were left with a thin rain saturated snowpack capped by a stout rain crust up to 4500′.  Above 4500′ much deeper snowpacks existed due to significant early season snowfall at upper elevations.

Dry and cold conditions along with moderate outflow winds finished out the month of October.

On 11/1 precipitation returned with 18 inches of snow and ~1″ of SWE on Thompson Pass.  This new snow was initially reactive with several natural D2 avalanches reported on Thompson Pass.  These slides were running on a firm bed surface consisting of old rain crusts and old wind slabs from October.

On 11/4 a strong north wind event kicked up with 65 mph+ winds on Thompson Pass.  Our snowpack received significant damage as already thin snow below 4500′ was stripped down to old wind slabs, rain crusts and the ground.  

Precipitation returned on 11/8 and became heavy on 11/11.  Storm totals of around 50 inches were recorded at Thompson Pass DOT between 11/8-11/13.  Snow lines rose to ~3000′ near the tail end of the storm with heavy rain occurring in low lying areas.

Skies cleared on 11/14 through 11/18 with a strong temperature inversion setting up.  Valley temperatures north of Thompson Pass fell to 0° F with above freezing temperatures existing above 4000 feet.  Valdez temps remained mild.  This weather allowed for widespread surface hoar up to 1 cm to develop in low lying areas.  

Precipitation returned on 11/19, with incremental snowfall on Thompson Pass and areas north.  The Valdez area received rain during this period.  12 inches have been recorded at TP DOT between 11/9-11/23.

11/26-11/29- Strong outflow (N) wind event.  Many areas below 3000′ were stripped to the 11/13 rain crust, destroying the 11/19 BSH layer.



The avalanche hazard is Moderate above 4000 feet in the Intermountain zone.   Above freezing temperatures at high elevation have been occurring for 24 hours.  There is the small chance that wind slabs or persistent slabs could reactivate at upper elevations and create dangerous hard slab avalanches 2-3 feet deep.  Low avalanche hazard exists below 4000 feet where old wind slabs are locked up and triggering them is unlikely.


Posted by Gareth Brown 12/4  8:00am.


For a description of avalanche problems, weather information, season history and more click the (+ full forecast) button.  Avalanche forecasts will be issued Wednesday-Sunday.