December 23, 2017

Issued: Sat, Dec 23, 2017 at 8AM

Expires: Tue, Dec 26, 2017

Don’t be tempted to follow other’s tracks if they don’t match your risk tolerance.  Colder temperatures make the consequences of a backcountry incident even more significant.  Continued good visibility will make it tempting to test new areas. Cautious route finding and conservative decision making essential. Re-group out of harm’s way.


Above 2,500ft Considerable

1,800 to 2,500ft Moderate

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

Tuesday’s (12/19) storm included lower density snow and moderate winds – expect windslab on lee features.  Pockets lee of ridges and gullies are likely still sensitive to human trigger.  Expect to find cross loaded features and wind pillows.

The most recent storm snow is becoming increasingly cohesive, creating a slab of it’s own.  In one test pit dug yesterday (12/22) at 4600′ on a south aspect, the interface of the new and old snow was 30″ (76cm) from the surface and was unreactive.

Last snowfall ended Dec. 19 leaving 10-15″ (25-38cm) of dry snow. The Dec.2-14 storm snow totaled 110″. Current Thompson Pass depth is 6+ feet (200cm) with depth increasing with elevation. On Little Girls at about 3500′, Dec.15, an observer reported finding an average snowpack depth of 8-9′ with 4-5′ of that being December’s storm snow.

Recent Avalanche Activity

The existing snowpack has now mostly adjusted to the additional load of Tuesday’s (12/19) storm.   Clear to overcast skies today allow for periods of good visibility.  Occasional gusts capable of transporting surface snow will continue to cross-load features.  Within the past few days, at various aspects throughout the advisory area, a few pockets of naturally triggered windslab and loose snow to size D1 (and one size D2) were observed primarily above 3000′ lee of ridges and gully walls, and near rocky outcrops.  Yesterday, no new avalanche activity was reported or observed.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):   4/15
Ridgetop Wind Forecast (direction/mph):  NE/3-15
Snowfall (in/water equivalent): 0.1″ /0.01″
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   3 /NE 8 /NNE
Max Wind Gust (mph) / Direction   7 /NE  15 /NNE
Temperature Min / Max (*F) 16 /25 9/20

Weather Forecast:

Light NE wind. Broken skies.  Variable temperatures below freezing throughout the advisory area.

Additional Info & Media


SNOW HISTORY: Valdez 12/22 AM Thompson Pass 12/22 AM
24 Hour Snow / Water Equiv. 0”/ 0.01″ 0″ /0.11″
Storm Snow /Water Equiv. [12/10-18]  3.5″ /3.5″snow+rain 46″ /6.4″
Current Snow Depth 16″ 60″
December Snow / Water Equiv. 38″ /13.17″ 132″ / 17.6″
Total Winter Snowfall / Water Equiv. 51″ /15.42” 197″ / 23.1″
Snowload in Valdez 45 lbs/sq. ft.


Nicks Valley at 4200 ft (in): 0″ / ?” / ?”
Upper Tsaina at 1750 ft (in): 0″ / 6″ /1.9″
Sugarloaf at 550 ft (in): 0″/ ?” /3.8″
SNOW DEPTH & WATER SURVEY (12/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  ″  ″
Milepost 18
Milepost 29 Worthington Flats
Milepost 37 Tsaina River bridge
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:

Posted in Continental Forecasts, Intermountain Forecasts, Maritime Forecasts, VAC Forecasts.

Forecaster: Ryan Van Luit