Spring 2018/Special Avalanche Advisory

Issued: Sat, May 05, 2018 at 10PM

Expires: Tue, May 08, 2018

Special Avalanche Advisory Saturday Evening, May 5 2018

Thompson Pass has received 33” of wet heavy snow since the morning of May 4th. A few slab avalanches and several point release(sluff) avalanches were visible during a break in the clouds Saturday afternoon around the Port of Valdez.

It seems like there might be a break in the weather on Monday/Tuesday. Direct sunlight will increase the avalanche hazard rapidly. Please be aware of the extreme consequences of being caught in an avalanche due to the several feet of new snow that has fallen the last 10 days. Most of the time there is no escaping an avalanche of this type. Our Condolences go out to the family and friends of Chad.

Above 2,500ft High

1,800 to 2,500ft High

Below 1,800ft Low

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

The avalanche danger is variable and can range from Low to High. Travelling early in the day is recommended, as conditions can change rapidly in short periods of time due to daytime warming. Pay careful attention to the integrity of the surface crusts formed overnight and rising air temperatures during the day. Dry slab avalanche danger may also exist during spring snow storms.

SNOWPACK DISCUSSION:     The end of April spring storms has brought 3-4 feet of new snow above 4000′ with the new snow drifted by strong winds.

Snow depths generally range from 30-350cm, including on glaciated terrain.

Check out our public observations.

Avalanche Canada has broken down the conditions you’re most likely to encounter into the following four scenarios.
1. Cold and Snowy: when winter storms roll through
2. Daily Melt-Freeze Cycles: Warm during the day, cold overnight
3. All Melt, No Freeze: Intense warming with no overnight re-freeze
4. All Freeze, No Melt: Cool weather with little or no melting

Each scenario has specific weather, snowpack, and avalanche characteristics. Each has trip planning advice. And each requires a different approach in terms of risk management. It’s up to you to decide which scenario applies to your specific location and situation. You may find basic guidance as to which scenario is the most applicable in the headline of the avalanche forecast for your region. You should also check the weather forecast, consider past weather patterns, and look for area specific information from knowledgeable people.

Recent Avalanche Activity

May 3: numerous new snow avalanches observed with the end of April series of snow storms, mostly point releases to size D2.5 in lower and mid-elevations. A few new observations of avalanche activity in the upper elevations, mostly point releases.

See reports in our public observations.

Recent Weather

Expect a lot of new snow to accumulate above the freezing level Saturday May 5.

Additional Info & Media

SNOW HISTORY: Valdez 4/29 AM Thompson Pass 5/3 AM
24 Hour Snow / Water Equiv. 0”/ 0.37″ 1″ / 0.05″
Storm Snow /Water Equiv. (4/21-5/2) 0” / 3.98″ 44″ / 3.8″
Current Snow Depth 0″ 75″
May Snow / Water Equiv. 0″ / ~″ 11″ / 1.5″
Total Winter Snowfall / Water Equiv. 132.59″ / 31.18” 424″ / 41.2″
Snowload in Valdez 0 lbs/sq. ft.


SNOW DEPTH & WATER SURVEY (5/1/2018) Depth Snow Water Equivalent
Milepost 2.5 Valdez  ″  ″
Milepost 18
Milepost 29 Worthington Flats 64.6″ 25.8″
Milepost 37 Tsaina River bridge 40.2″ 16″
This survey is done the first week of each month.

Weather Quicklinks:



  • 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


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


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 Continental Forecasts, Intermountain Forecasts, Maritime Forecasts.
Kyle Sobek

Forecaster: Kyle Sobek