Valdez

Forecast Expired - 12/04/2020

Above 3,000ftConsiderable

1,500 to 3,000ftConsiderable

Below 1,500ftLow

Degrees of Avalanche Danger

Low
Moderate
Considerable
High
Extreme

Avalanche Problems

Problem 1

Storm Snow:

We are at the tail end of a major storm that has deposited over 4″ of water to Valdez since 11/30.  This translates to over 3 feet of snow for some places that were above the freezing line throughout the storm, above ~3000′.   We are still within 24 hours of this event, the upper section of the snowpack will need time to adjust to this new snow.  Human triggered storm snow avalanches will remain likely 12/3.  Avoid slopes steeper than 35°, terrain traps and convex terrain features.

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Deep Slab:

Weak Basal facets exist at the ground which have shown propagation energy in stability tests as recent as 11/30.  These layers have been put to the test with the latest storm, and there may be areas that are still hanginging on by their fingernails.  It is possible that a person or snowmachine could tip the balance and create very large destructive avalanches that would include the entire winters snowpack.  Avoid large avalanche slopes and unsupported terrain.

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

12/3- Numerous avalanches were observed north of Thompson Pass with many avalanches failing at the ground.  Clouds prevented a complete picture of the activity. Observations were not made south of Thompson Pass.

Avalanches observed from 46 mile towards Thompson Pass:

Three Pigs: Nearly every path on the SE face ran with debris deposits stopping  in the top 1/3 of aprons, thick alders prevented slides from running full path.  These were mostly D3 avalanches.

40.5 Mile Peak: Many paths running similar to Three Pigs, with the Shovel approach gully running full path to the Tsaina river.  Mainly W-NW aspects, D3’s

Max High (Peak on the southern extent of Hippie Ridge)  had a D3 avalanche with a crown near 5500′,SW aspect.

The main activity noted, was on the buttresses on the east side of the pass, from Cracked Ice through North Odessey Gully.  Every buttress had significant avalanche activity originating ~4000-5000′.  Many of these failed at the ground, north – northwest aspect.   Pictures below.

School Bus and North Odyssey Gully both ran with debris in the runouts.  Starting zones were obscured by clouds.

12/2- DOT reported a natural D2.5-3 avalanche that hit the Lowe river at Snowslide Gulch.

11/30- Natural avalanche observed on 40.5 mile peak just to the South of the Shovel.  West aspect, ~4500′, crown ~200′ wide, poor light prevented further observation.  SS-N-R1-D2-U.

11/29: Natural avalanche observed on Billy Mitchell Cry babys shoulder, similar elevation as 11/16 slide but originated a couple hundred meters further west.  Released from ~4000′ with a crown length of ~ 200 meters, North aspect, ~ 37°, failed at the ground.  HS-N-R2-D2.5-G 

11/16: Natural avalanche observed on Billy Mitchell “Cry babys shoulder”.  Released from~3500′ with a crown length of ~200 meters, North aspect. This slide was triggered by recent NE wind cross loading the slope.  SS-N-R2-D2-U

11/15: Natural avalanche observed in Loveland Basin on a South aspect, down the ridge from Tones Temple.  This slide was triggered by recent NE wind loading and failed at the ground. SS-N-R1-D2-G

 

 

 

Weather

12/3- The latest storm that has affected our area the last 72 hours is exiting.  Precipitation is forecasted to taper off with falling temperatures.

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
management.

                   Today        Tonight

Temp at 1000`      34 F         19 F

Temp at 3000`      20 F         18 F

Chance of precip   80%          50%

Precip amount
(above 1000 FT)    0.07 in      0.03 in

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

Snow level         sea level    sea level

Wind 3000` ridges  SE 6-13 mph  E 7-15 mph

Remarks...None.









Date: 12/3
24 hr snow (inches)
HN24W (snow water equivalent inches)
High Temp (F)
Low Temp (F)
Weekly SWE Inches (Monday-Sunday)
December snowfall
Season snowfall
HS (snowpack depth inches)




Valdez
0
.91
36
29
3.71
5
48
23




Thompson Pass
13
1.5
32
20
5.18
35
153
48




46 Mile
0
.91
38
31
2.84
9
38
14






Thompson Pass weather history 20/21.  Click on links below the images to see full size view




 


 


 


 


 


 


 


TP NOV as of 11/18 


 


Announcements
The avalanche hazard is Considerable at mid and upper elevations.  Human triggered avalanches are likely and natural avalanches are possible.  We are within 24 hours of a major storm that has deposited over 30 ” of new snow since the evening of 11/30 at the Nick’s snotel at 4500′ feet.  Allow the snowpack time to adjust to this added weight.  Conservative terrain choices will be critical 12/3.  The hazard will be decreasing as the storm exits, temperatures fall and precipitation ends.


At Low elevations the avalanche hazard is low, a rain soaked snowpack has refrozen and gained strength.


For more information click the (+full forecast) button below.


Your observations are valuable!   If you have been out recreating in the mountains leave an observation.