Arctic Man Avalanche Forecast

Issued: Wed, Apr 11, 2018 at 3PM

Expires: Wed, Apr 11, 2018

Come see us next to the beer tent! Please let us know if you have seen any natural/human triggered avalanches.

Above 4,000ft Moderate

3,000 to 4,000ft Low

Below 3,000ft Low

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

Wet Avalanches:
Elevation:   Below 4000′
Aspect:   SE – S – SW
Terrain:   Southerly facing terrain >25 degrees exposed to sun
Sensitivity:   Non-reactive – Responsive as sun and warmer temperatures dominate
Distribution:   Specific
Likelihood (Human Triggered): Possible
Size:   Small 
Danger Trend:   Increasing with solar input and warmer temperatures
Forecaster Confidence:    Good

Persistent Slab:
Elevation:   Above 4000′
Aspect:  All
Terrain:   Above 32 Degree Slope Angle
Sensitivity:  Stubborn
Distribution:   Widespread
Likelihood (Human Triggered): Possible
Size:   Large
Danger Trend:   Steady
Forecaster Confidence:    Poor

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION: The mostly likely snowmachine triggered avalanches will be in the afternoon when the sun has been beating down on the snow. Temperatures are expected to stay below 40 degrees F over the next couple days which will generally keep things glued together. Areas like rocky outcroppings, isolated brush patches, and south facing slopes are where you will most likely trigger these afternoon slides. Extensive slope testing on snowmachines has produced no results so far but stability can change with the temperature.

Limited observations above 5000′ but knowing the weak snowpack structure (sugary/facted base) we have reason to believe there is a possibility of triggering a large slab avalanche. These “Persistent Slab Avalanches” are most likely to be triggered in areas that have remained cold, like north facing slopes and glaciated areas.

Recent Avalanche Activity

Solar Triggered Wet Avalanche Near the Race Course on A Steep (50 degree) Angle

Older (2+ weeks) Deep Persistent Natural Avalanche in the Drainage Immediately North of “The Tit”

Recent Weather

Recent daytime temperatures have reached into the upper 30’s. Night time temperatures are forecasted to drop into the high teens. Thursday will bring partly sunny skies with daytime temperatures reaching close to 40 degrees F. Read the whole Arctic Man spot forecast issued by the National Weather Service Here

Additional Info & Media

SNOW HISTORY: Valdez 2/24 AM Thompson Pass 2/24 AM
24 Hour Snow / Water Equiv. <0″/0″ 0″ /0″
Storm Snow /Water Equiv. (2/22-2/23) 0.6” /0.05″ 1″ /0.1″
Current Snow Depth 48″ 49″
February Snow / Water Equiv. 44.9″ /5″ 43″ / 5.1″
Total Winter Snowfall / Water Equiv. 222.8″ /20.9” 282″ / 27.7″
Snowload in Valdez ~ lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (2/24 AM)/STORM TOTAL (2/22-23)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 0″ / 0″ / 0″
Upper Tsaina at 1750 ft (in): 0″ / 0″ / 0″
Sugarloaf at 550 ft (in): 0″/ 1″ / 0.1″
SNOW DEPTH & WATER SURVEY (2/1/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.5″  9.8″
Milepost 18 43.9″ 9.5″
Milepost 29 Worthington Flats 61.5″ 16″
Milepost 37 Tsaina River bridge 42.1″ 9.3″
This survey is done the first week of each month.

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Thompson Pass RWIS weather station <here>
  • MP 30 Nicks (Happy) Valley weather station at 4200 feet <here> (scroll to Nicks Valley)
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>
  • Further weather resources <here>

SNOW CLIMATE ZONES:

  • coastal-zone-iconMaritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • intermountain-zone-iconInter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • interior-zone-iconContinental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).

Photo of Thompson Pass

thompson-pass-ski-runs

Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)

climate-zones-topoclimate-zones-satellitegoogle-earth1

Run Map of Thompson Pass Area (Sean Wisner) (2MB download)
VAC Run Map Thompson Pass

NEWS: Our region is “one of the snowiest places on earth” – Serendipity / Rendezvous snowfall record set in 1963 <here>.

Free smart phone avalanche forecasts at: http://www.avalancheforecasts.com/

Posted in EARAC Forecasts.
Kyle Sobek

Forecaster: Kyle Sobek