December 3, 2017

Issued: Sun, Dec 03, 2017 at 12PM

Expires: Wed, Dec 06, 2017

Expect HIGH avalanche danger starting Sunday

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

The foot of new snow deposited at the end of November sits over sturdy bed surfaces of October snow and November windslabs. The new snow is being drifted with moderate southerly wind.

Anticipate:

  1. weaker sugary faceted snow over the hard November north winds windslabs, and
  2. the new snows of the November 24-28 storm and the December 2nd storm be colder weaker snow than the warmer denser forecast storm snows drifted by southerly winds windslabs – ‘upside down’ snow.

Excellent field reports <here>. Thanks Gareth and PWS College avalanche class.

Recent Avalanche Activity

No recent avalanches observed, yet.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):   27/30
Ridgetop Wind Forecast (direction/mph):  SE/20-40
Snowfall (in/water equivalent): 10-20″ /1.2 “
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   0-2 /var  30 /SE
Max Wind Gust (mph) / Direction   5 /var  40 /SE
Temperature Min / Max (*F) 25 /31 24 /29

Weather Forecast:

This week’s accompanying atmospheric river may have as much as a foot of water (!) which will deposit a lot of snow in the upper elevations. Expect rain at sea level. With the warm wet air pushed up the Copper River through the Tsaina gorge and into the lower elevations of the continental snow climate zone north of Thompson Pass, the freezing level may rise above the elevation of Thompson Pass.

Additional Info & Media

 

SNOW HISTORY: Valdez 12/3 AM Thompson Pass 12/3 AM
24 Hour Snow / Water Equiv. 12”/0.6″ 5″ /05″
Storm Snow /Water Equiv.  12″ /0.6″ 5″ /0.5″
Current Snow Depth 18″ 17″
December Snow / Water Equiv. 13″ /0.6″ 5″ / 0.5″
Total Winter Snowfall / Water Equiv. 77″ /7.4” 70″ / 7.3″
Snowload in Valdez ~ lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (10/22 AM)/STORM TOTAL (10/22-present)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): ” / ” / “
Upper Tsaina at 1750 ft (in): ” / ” / “
Sugarloaf at 550 ft (in): “/ ” / “
SNOW DEPTH & WATER SURVEY (10/2017) 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:

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 Continental Forecasts, Intermountain Forecasts, Maritime Forecasts, VAC Forecasts.
Pete Carter

Forecaster: Pete Carter