Wednesday-Saturday 1/25-1/28

Issued: Wed, Jan 25, 2017 at 8AM

Expires: Sat, Jan 28, 2017

Poor visibility will limit your ability to see what the storm is doing above you. Choose conservative terrain avoiding terrain traps such as gullies and slopes above cliffs.

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

Below 1,800ft Moderate

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

WEDNESDAY THURSDAY FRIDAY & SATURDAY

DANGER SCALE

WIND SLAB:
Elevation:
 Above 1800′
Aspect: New snow drifting north and westerly aspects
Terrain:
Ridges, gullies, steep unsupported bowls, rollovers
Sensitivity:
 Responsive
Distribution:
 
Specific
Likelihood (Human Triggered): 
Likely
Size:
 Small-Large
Danger Trend:
 Increasing 
Forecaster Confidence: 
Fair

PERSISTENT SLAB:
Elevation: 
Mostly above 2500′
Aspect: 
All
Terrain: 
Steep rocky slopes where facets exist under old and between windslab, especially interior of Thompson Pass
Sensitivity: 
Stubborn
Distribution: 
Specific
Likelihood (Human Triggered): 
Possible
Size: 
Small – Large
Danger Trend: 
Decreasing with warming
Forecaster Confidence: 
Poor

STORM SNOW:
Elevation:
 All
Aspect: 
All
Terrain: 
Steeper than 35 degress
Sensitivity: 
Reactive
Distribution: 
Widespread
Likelihood (Human Triggered): 
Likely
Size: 
Small – Large
Danger Trend:
 Increasing 
Forecaster Confidence: 
Good

AVALANCHE PROBLEM SCALE DESCRIPTORS:
Sensitivity: Non-reactive, Stubborn, Responsive, Touchy
Distribution: Isolated, Specific, Widespread
Likelihood: Unlikely, Possible, Likely, Nearly Certain
Size: Small, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor

LIST OF AVALANCHE PROBLEMS <here>

SNOWPACK DISCUSSION: Southerly wind is transporting the 5 inches that fell overnight at Thompson Pass.

 The extreme northerly outflow wind events of January 6 and 18 have left Thompson Pass and most of the upper elevation terrain wind scoured. The new snow of January 23 came in very cold and lays on various bed surfaces of faceted sugar old snow, surface hoar, and windslab. As the residual northerly outflow winds are turned around Tuesday to onshore southerlies, expect a warmer slabs of new windslab and storm snow sitting over the weaker interface beneath.

Find more photos and observations at the bottom of the page. Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

No new observations.

coastal-zone-iconMaritime (Coastal):

  • No new observations.

intermountain-zone-iconInter-Mountain (Transitional):  

  • No new observations.

interior-zone-iconContinental (Interior):  

  • No new observations.

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  10 / 30
Ridgetop Wind Forecast (direction/mph): SE / 5-30
Snowfall (in):  6-7
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   3 / var  25 / E
Max Wind Gust (mph) / Direction  11 / NE  35 / SE
Temperature Min / Max (*F)  30 / 35  8 / 25

Weather Forecast:     Snow accumulating 5-12 more inches through Friday morning at Thompson Pass, with rain/snow mix at sea level. Moderate to strong southeast wind near passes and ridgetops. Freezing line could be as high at 2800′. Precip is forecast to continue into the weekend with a triple point low pushing into Prince William Sound.

Additional Info & Media

SNOW HISTORY: Valdez 1/25 AM Thompson Pass 1/25 AM
24 Hour Snow / Water Equiv. 8.6” /0.5″ 5″ /0.4″
Storm Snow /Water Equiv. (1/23-25) 16” /0.9″ 13″ /1″
Current Snow Depth 49″ 36″
January Snow / Water Equiv. 62.8″ /4.1″ 67″ / 5.2″
Total Winter Snowfall / Water Equiv. 158.9″ / 13.9” 210″ / 19.6″
Snowload in Valdez 44.72 lbs/sq. ft.

 

SNOWFALL for LAST 24 HRS at OTHER STATIONS:
Nicks Valley at 4200 ft (in): 4″
Upper Tsaina at 1750 ft (in): 3″
Sugarloaf at 550 ft (in): 5″
SNOW DEPTH & WATER SURVEY (1/3/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  22.7″  4.7″
Milepost 18 27.9″ 5.9″
Milepost 29 Worthington Flats 44″ 9.9″
Milepost 37 Tsaina River bridge 33.8″ 5.6″
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 VAC Forecasts.
Pete Carter

Forecaster: Pete Carter