Sunday-Wednesday 1/21-1/24

Issued: Sun, Jan 21, 2018 at 8AM

Expires: Wed, Jan 24, 2018

Above treeline, the Jan.13-16 storm snow is being transported by strong outflow wind. Avoid crossloaded gully walls and actively loading lee features. If the snow begins to get stiff, sound hollow, or you see shooting cracks, choose another slope without wind affect. Windchill will be significant.

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

SUNDAY MONDAY TUESDAY
& WEDNESDAY
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-Likely
Size:   
Small – Large
Danger Trend:
   Steady
Forecaster Confidence:
   Fair

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

In areas exposed to strong outflow wind, the recent storm snow is being redistributed. Jan.13-16 totals ranged from 18’’ (46cm) near Kenny Lake/Chitina to 41’’ (104cm) at Thompson Pass. Expect scoured ridgelines, while lee slopes could have very deep pockets of fresh windslab.

In wind protected zones, expect the storm snow to continue settling. Watch for characteristics of a slab.

Previous to this 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 3-4’ down.  Be on the look out for natural avalanche activity on this old layer. If you see natural avalanches on this layer, use extreme caution on slopes of similar aspect/elevation.

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

Recent Avalanche Activity

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.

January 19, two riders spent the day in the Kenny Lake area and reported seeing no natural or human triggered avalanches and experienced no additional signs of instability including whumphing or cracking.

Several small windslab avalanches size D1 were observed Thursday Jan.18 at 3200′, visible from the Loveland parking lot to the lee of gullies.  These seem to have been naturally triggered and were likely a day or two old.  All of them were facing southeast, which indicate they were created by a northerly outflow wind.

 

 

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  0/ 14
Ridgetop Wind Forecast (direction/mph): NE / 12-50
Snowfall (in): 0
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   15 / NE  35 / NE
Max Wind Gust (mph) / Direction  32 / NE  53/ NE
Temperature Min / Max (*F)  24 / 29  5 / 9

Weather Forecast:  Overcast and cold. Outflow northerly wind through the week. Possible flurries with no significant accumulation. Significant windchill.

Additional Info & Media

SNOW HISTORY: Valdez 1/21 AM Thompson Pass 1/21 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″ 86″
January Snow / Water Equiv. 12.57″ / 5.81 ″ 73″ / ~6.5″
Total Winter Snowfall / Water Equiv. 77.43″ / 22.02” 281″ / ~30″
Snowload in Valdez 40 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.
Sarah Carter

Forecaster: Sarah Carter