Valdez

Forecast Expired - 03/19/2023

Above 4,000ftConsiderable

2,000 to 4,000ftConsiderable

Below 2,000ftConsiderable

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Storm Snow:

All three of our forecast zones have received significant snowfall in the last 36 hours. Storm totals of 12-24 inches have been recorded above 1000 feet with higher amounts expected in the upper mountains.    Winds out of multiple directions were moderate to strong yesterday promoting slab development on multiple aspects.  An additional 4-6 inches of snow will continue to build the depth of slabs and continue to stress the upper snowpack.

 

New snow began with temperatures in the single digits and were deposited on a variable wind damaged crust.  On 3/17 instabilities were observed within the lower half of the storm snow at a density change with small shooting cracks, easy hand shear results and easy results on ECT‘s all pointing to sensitive storm slabs that will be reactive to human triggers on slopes steeper than 30°.   Human triggered avalanches will be likely today on slopes steeper than 30° especially where the surface has been stiffened by wind.  Convex and wind loaded terrain will be the most sensitive.

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Deep Slab:

 Over three weeks of dry and windy weather previous to this storm has decreased the height of our snowpack and caused layers near the ground to facet (loose strength).  

 

Todays storm is adding stress to weak snow at the bottom of our snowpack.  It is currently unlikely for human triggered or natural avalanches to occur at this layer.  This is due to the strength of old wind affected snow at this interface, and an insufficient amount of new snow to tip the scales.  Depth hoar may become a concern later in the season if our area starts to receive more consistent 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.

 

 

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

No natural or human triggered avalanches have been reported or observed the last 7 days.  Last activity observed occurred on the 7th and 8th during a strong temperature inversion that brought above freezing temperatures to mid and upper elevations for an extended period.  Strong north winds on 3/9-10 may have produced some small avalanches, although none have been reported or observed.

 

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, mainly before 4pm. High near 34. Northeast wind 5 to 10 mph. Chance of precipitation is 80%. Total daytime snow accumulation of 3 to 5 inches possible.
Tonight
Snow before 1am, then snow showers, mainly after 1am. Low around 19. Northeast wind around 5 mph becoming south after midnight. Chance of precipitation is 80%. New snow accumulation of 1 to 2 inches possible.
Sunday
Snow showers likely, mainly before 7am. Cloudy, then gradually becoming mostly sunny, with a high near 35. South wind around 5 mph becoming calm in the morning. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.
Sunday Night
Mostly cloudy, with a low around 10. Calm wind becoming northwest around 5 mph.
Monday
Mostly sunny, with a high near 31. Calm wind becoming south around 5 mph in the afternoon.
Monday Night
Isolated snow showers before 10pm, then a chance of snow after 10pm. Mostly cloudy, with a low around 12. South wind around 5 mph. Chance of precipitation is 30%.
Detailed forecast for Thompson Pass Mid elevation (2000-4000 Feet)
Date               Saturday 03/18/23       Sunday 03/19/23         
Time (LT)          06    12    18    00    06    12    18    00    06
Cloud Cover        OV    OV    OV    OV    OV    SC    SC    BK    BK
Cloud Cover (%)    85   100    95   100    95    50    45    55    50
Temperature        23    27    29    28    22    23    25    12     9
Max/Min Temp                   30          19          29           9
Wind Dir           NE    NE     E     E     S    SE     E    NE    NE
Wind (mph)          4    14    17    23    10     3     2     8     5
Wind Gust (mph)    17    32    34    40    23    16    14    19      
Precip Prob (%)    40    90    50    90    80    30    10     5     5
Precip Type         S     S     S     S     S     S     S            
12 Hour QPF                  0.34        0.29        0.04        0.00
12 Hour Snow                  4.0         3.1         0.2         0.0
Snow Level (kft)  0.0   0.2   1.1   1.1   0.0   0.0   0.0   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:

03/18

24 hr snow HN24W* High temp Low temp 72 hour SWE* March snowfall Seasonal snowfall Snowpack Depth
Valdez 3 .5 34 27 .9 13 231 53
Thompson Pass  ~20 N/O 18 9 N/O 15 408 40
46 mile ~14 N/O 32 19 N/O 26 ~108** 58

 

 

*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 Considerable at all elevations. 12-24 inches of new snow has accumulated at low elevations with higher amounts and moderate to strong winds at upper elevation.  This new snow will need time to settle and bond to the underlying snowpack.  In the meantime, human triggered avalanches are likely up to 3 feet in depth and natural avalanches are possible.

 

Posted by Gareth Brown 03/18  8:15 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.