Friday-Monday 2/2-2/5

Issued: Fri, Feb 02, 2018 at 8AM

Expires: Mon, Feb 05, 2018

The most likely place you will trigger an avalanche is lee of gullies, chutes, ramps, ridges, rollovers, and cornices that have been wind loaded by the strong and persistent winds.

Above 2,500ft Moderate

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

Thursday Friday Saturday
& Sunday
2-moderate 2-moderate

DANGER SCALE

 

 

WIND SLAB:
Elevation:
   Above 2000′
Aspect:  
 Lee of ridges, gullies, ridgetops
Terrain: 
  All terrain exposed to wind
Sensitivity:
   Responsive
Distribution:   
Specific
Likelihood (Human Triggered): 
Possible
Size:   
Small – Large
Danger Trend:
 Steady
Forecaster Confidence:
   Good

PERSISTENT SLAB:
Elevation:
   Above 2500′
Aspect:
   All
Terrain: 
  35+ degrees steepness
Sensitivity:
   Stubborn
Distribution:   
Specific
Likelihood (Human Triggered):   
Possible
Size:   
Small – Large
Danger Trend:
   Steady 
Forecaster Confidence:
   Poor

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: 

It’s been almost 2 weeks since the last significant snow storm.  The 80+ MPH North winds have done some damage throughout the advisory area,  at all elevations. You are most likely to trigger a slide in wind loaded areas. As you travel throughout the day take note about which direction the wind is coming from, and think about how it blows snow across the landscape. Avoid areas that have been loaded by the wind, especially slopes steeper than 30 degrees.

Previous to the Jan.13-16 storm there were concerns of a persistent weak layer about 1-2’ under the snow surface. This persistent weak layer (surface hoar and/or near-surface facets) is now buried 2-4’ down.  Our snowpack tests indicate that this layer is persisting and remains a concern.  We encourage you to dig for and test this layer, especially above 3000′.  Jan.26 on a NW aspect across from Rice Mountain at 3200′, we found this layer 28″ (70cm) below the snow surface and it was stubborn to trigger. This layer was confirmed by another party Sunday January 28 closer to Thompson Pass. It was found 32″ (80cm) down and propagated when tested.

Below 2000′ (the rainline from the Jan.13-16 storm) the snow is frozen in place with a beefy crust.

Recent Avalanche Activity

January 28: several size 1-2 windslab avalanches observed lee to north outflow wind, mostly off ridgelines and gully walls above 3000′ through the Thompson Pass corridor.

Jan.28, 2018 Natural windslab avalanche on west facing gully wall above MP 33. Ryan Van Luit photo.

Wind transport Jan.28, 2018. Ryan Van Luit photos.

 

January 19, a snowmachiner triggered an avalanche size D2 between Heiden Glacier (near “The Books”) and Deserted Glacier. The weak layer may have been near-surface facets.

  • NW aspect
  • ~35< slope
  • ~5000′ in elevation
  • 1-3′ (30-91cm) crown
  • No injuries reported

See photo and map below.  Photo credit: Clyde Hewitt.

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  -8/ 9
Ridgetop Wind Forecast (direction/mph): NE / 14-36
Snowfall (in): 0
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   14/ ENE  52 / NE
Max Wind Gust (mph) / Direction  35 / NE  72/ NE
Temperature Min / Max (*F)  13 / 21  -7 / 1

Weather Forecast:  High winds continue, with gust over 60mph. High temperatures around 0*F at the pass.  No  precipitation for the Valdez region for the next few days.

Additional Info & Media

SNOW HISTORY: Valdez 2/2AM Thompson Pass 2/2 AM
24 Hour Snow / Water Equiv. 0”/ 0″ 0″ / 0″
Storm Snow /Water Equiv. (1/13-16) 2” / 2.82″ rain 41″ / ~3″
Current Snow Depth 23.5″ 75″
January Snow / Water Equiv. 12.78″ / 6.02 ″ 83″ / ~6.5″
Total Winter Snowfall / Water Equiv. 77.64″ / 22.05” 290″ / ~30″
Snowload in Valdez 37 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS / STORM TOTAL (Jan.13-16) / STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 0″ / 22″ / ?”
Upper Tsaina at 1750 ft (in): 0″ / 19″ / 2″
Sugarloaf at 550 ft (in): 0″ /rain” / ?”
SNOW DEPTH & WATER SURVEY (2/1/2017) 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.

Forecaster: Ryan Van Luit