Valdez

Forecast Expired - 03/23/2023

Above 4,000ftModerate

2,000 to 4,000ftModerate

Below 2,000ftModerate

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Wind Slab:

The most likely avalanche problem to encounter within our forecast zone will be wind slab.  The Hamilton storm cycle (3/17-18) provided us with 2-3 feet of new snow above 1000′.  This new snow fell atop very strong wind affected snow in most places along the road corridor.  Good bonding has been observed and reported in multiple locations at the new/old interface.  A density change (weakness) exists within the storm snow, this has been observed to be gaining strength although assessment remains necessary and human triggered avalanches remain possible in steep terrain especially where wind slabs exist.

 

Light snowfall and moderate to strong east winds are forecasted today that will build fresh wind slabs and add to older wind loads on the lee side of high elevation ridges, terrain features and cross loaded gullies.  Human triggered avalanches are possible 1-3 feet in depth on specific terrain features.  Watch for signs of wind slab at the surface including hard snow over soft and pay attention to red flags such as shooting cracks that would indicate unstable snow.

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Persistent Slab:

 The majority of locations in our forecast zone have shown the Hamilton storm snow from 3/17 sits atop very strong wind damaged snow with good bonding observed.  In areas that were more protected from late February-early March north winds, this interface consists of near surface facets.  This difference in interface is important to identify.

 

 Human triggered avalanches are possible up to 4 feet deep in areas where facets are present at the new/old interface or where storm slab that are deeper than 3 feet exist.  These conditions are not as likely to be found within our forecast zone but have been reported in areas to the southeast of Thompson Pass that received higher storm totals, and in more continental locations where the underlying snowpack is weaker.  Ski pole probing and digging snowpits are good ways to identify what type of interface the recent new snow is sitting on.  Light snowfall and moderate to strong east winds today will be adding weight to persistent slabs.

 

Other persistent weak layers exist in our mid to lower snowpack.  These are currently unlikely to be affected where very strong wind affected snow exists at the 3/17 interface.

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 3

Deep Slab:

Weak snow exists at the base of our snowpack.  This weak snow is currently unlikely to be affected due to the strength of old wind affected snow at the 3/17 new/old interface.  Depth hoar may become a concern later in the season if our area continues to see major snowfall and the very strong wind damaged at the new/old interface starts to break down and loose strength within the snowpack.  As very hard wind slabs break down within the snowpack a person or machines weight will have a more direct affect on weak layers at the bottom of the snowpack.  In addition,  the increasing intensity of the sun will be putting pressure on deep layers during the heat of the day.

 

 

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

Below is a summary of observed Avalanche activity from the last 7 days.  Avalanches that were noted earlier in the season can be viewed by clicking the link below.

If you trigger or observe an avalanche consider leaving a  public observation.

Valdez Avalanche Activity

 

3/18-21- Several D1-D2 human triggered avalanches have been reported.  For the most part these have been outside our forecast zone and appear to be more likely in areas with either a weaker underlying snowpack (continental zone) or where storm totals were higher (SE of Thompson Pass).  Remote triggers have also been reported as the Hamilton storm slab has settled and gained cohesion.

 

3/17- Multiple D1-D2 natural storm slab avalanches were reported and observed along the road corridor.  These all failed within the storm snow with the exception of one deep persistent avalanche reported on Billy Mitchell.

Weather

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

NWS Watches, warnings and advisories

NONE
 NWS Point forecast for Thompson Pass
Today
Snow likely. Areas of blowing snow after 1pm. Cloudy, with a high near 30. East wind 15 to 20 mph increasing to 20 to 25 mph in the afternoon. Winds could gust as high as 30 mph. Chance of precipitation is 70%. Total daytime snow accumulation of 1 to 2 inches possible.
Tonight
Snow. Low around 22. East wind 15 to 20 mph becoming southwest 5 to 10 mph after midnight. Chance of precipitation is 90%. New snow accumulation of 2 to 4 inches possible.
Thursday
Snow. High near 30. Calm wind becoming southwest around 5 mph in the afternoon. Chance of precipitation is 90%. New snow accumulation of 1 to 2 inches possible.
Thursday Night
Snow likely, mainly before 7pm. Mostly cloudy, with a low around 16. South wind around 5 mph. Chance of precipitation is 60%.
Friday
A chance of snow before 10am, then snow showers, mainly between 10am and 4pm. High near 28. South wind 10 to 15 mph, with gusts as high as 20 mph. Chance of precipitation is 80%.
Friday Night
Scattered snow showers before 10pm. Mostly cloudy, with a low around 9. Southwest wind around 5 mph becoming northeast in the evening. Chance of precipitation is 40%.
Detailed forecast for Thompson Pass Mid elevation (2000-4000 Feet)
Date               Wednesday 03/22/23      Thursday 03/23/23       
Time (LT)          06    12    18    00    06    12    18    00    06
Cloud Cover        OV    OV    OV    OV    OV    OV    OV    OV    OV
Cloud Cover (%)    90    95   100   100    95   100    90    70    70
Temperature        19    23    29    26    22    27    28    19    17
Max/Min Temp                   30          21          30          17
Wind Dir           SE     E     E    SW     E     W    SW    SW     S
Wind (mph)         14    21    24     6     5     2     6     6    10
Wind Gust (mph)    29    42    36                                    
Precip Prob (%)    60    70    90    80    80    90    60    40    40
Precip Type         S     S     S     S     S     S     S     S     S
12 Hour QPF                  0.20        0.33        0.17        0.05
12 Hour Snow                  2.7         4.2         2.1         0.1
Snow Level (kft)  0.0   0.0   0.3   0.0   0.0   0.0   0.2   0.0   0.0
 Click on link below for Thompson Pass weather history graph:

https://docs.google.com/spreadsheets/d/e/2PACX-1vR_Fl5087NrNCo2BtsSaum-gxrx1QioHSO4YqEmjW76LhuDu9ZsSxbBCTl6zkYIFarys-5eM_7P5GpV/pubhtml

 

 

 

Date:

03/22

24 hr snow HN24W* High temp Low temp 72 hour SWE* March snowfall Seasonal snowfall Snowpack Depth
Valdez 2 .05 35 25 .09 15 233 54
Thompson Pass  2 N/O 23 18 N/O 54 422 N/O
46 mile N/O N/O 32 16 N/O 26 ~108** 56

 

 

*HN24W- 24 hour Snow water equivalent in inches

*SWESnow water equivalent

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

Additional Information

 

Click on the link below for a running summary of the seasons weather history.

Valdez Weather History

Announcements

The avalanche hazard is moderate at all elevations.  Human triggered avalanches are possible 1-3 feet deep in specific areas. Natural avalanches are unlikely.  Wind loaded terrain will be the most suspect.  Watch for signs of instability including shooting cracks, collapsing and natural avalanche activity that would indicate unstable snow.

 

Posted by Gareth Brown 03/22  7:45 am.

 

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

If you have pictures of recent natural or human triggered avalanches or notice signs of instability such as shooting cracks or collapsing, leave an observation to help improve forecast accuracy.