New Years Day-Wednesday

Issued: Sun, Jan 01, 2017 at 8AM

Expires: Wed, Jan 04, 2017

Many thanks to you who help support the Valdez Avalanche Center.

May 2017 be full of powder and fun! Happy New Year!

Clear skies today will let us see the wind transport. Choose to avoid slopes that are actively or have recently been windloaded.

If you get into snow that is more dense, cracks, or whumphs, you are most likely on a windslab. Consider the consequences if you or your party triggers the slope: are there gullies, cliffs, rocks, or a creek that could injure or bury you more deeply?

Above 2,500ft Considerable

1,800 to 2,500ft Moderate

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

SUNDAY MONDAY TUESDAY & WEDNESDAY

DANGER SCALE

WIND SLAB:
Elevation: Above 1800′
Aspect: mostly south and west
Terrain: Near ridgelines, gullies and rollovers
Sensitivity: Touchy
Distribution: Specific
Likelihood (Human Triggered): Likely
Size: Small to Medium
Danger Trend: Steady
Forecaster Confidence: Good

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: Medium
Danger Trend: Increasing with continued windloading
Forecaster Confidence: Poor

LOOSE SNOW:
Elevation: 
All
Aspect: 
All
Terrain: 
Greater than 30* and in runouts of wind loaded slopes above
Sensitivity: 
Responsive
Distribution: 
Widespread
Likelihood (Human Triggered): 
Possible
Size: 
Small to Medium
Danger Trend: 
Decreasing with time after 12/30-31 storm
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, Medium, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor

LIST OF AVALANCHE PROBLEMS <here>

SNOWPACK DISCUSSION: North wind picked up Saturday and continues to transport the 16″ Dec.30-31 storm snow at Thompson Pass. Windslab to 2 feet deep is expected on mid-upper elevation lee slopes.

The Road Run has avalanche terrain. With barely enough snow to cover rocks and alders, the road run is seeing use. Today is a prime day to be very careful due to the north wind loading snow onto The Wall and other steep slopes. A lot of times the first people who ride the road run ski/snowboard cut and trigger size 1-2 avalanches that ‘clean out’ the new slab. If the wind continues to move snow onto the slopes, each run will have fresh instability. Talk about your group’s plan and riding habits: Do you ride one at a time on the steep sections? Keep eyes on? Ready for rescue? Wear a beacon and carrying a probe and shovel? Know and have practiced this year?

coastal-zone-iconMaritime (Coastal):
Valdez town received 12″ out of the Dec.30-31 storm. With more snow and warmer temperatures, the maritime zone has a generally more uniform snowpack. Most of the recent avalanche activity observed involved the upper layers of the snowpack and occurred in steep, rocky terrain. We can’t write off colder, upper elevations harboring buried weak facets near the ground.

intermountain-zone-iconInter-mountain (Transitional):
Interior of Thompson Pass has stayed consistently cooler and received less snow than the coast. Early season facets at the ground and between layers of windslab are still a concern. In some areas tests show sudden collapse with propagation potential; see observation from 12/28. It is not out of the picture for heavy loads such as a snowmachine or multiple machines to trigger a wind loaded slope and have it step down to persistent weak layers, increasing the avalanche size and destructive potential.

Very easy failure at top of weak facets when isolating column up Nicks @ 4200'

Very easy failure at top of weak facets when isolating column up Nicks @ 4200′

Propagation supported up Nicks Valley @ 4200': PST 40/100 (end)

Propagation supported up Nicks Valley @ 4200′: PST 40/100 (end)

interior-zone-iconContinental (Interior):
More interior beyond Mile Post 37 and out past Billy Mitchell, the snowpack is thin and weaker. Recent avalanches stepped down to ground (similar to the how the Inter-Mountain zone was acting a month or more ago).

Find more photos and observations at the bottom of the page. Sharing your observations helps others make informed decisions.

Recent Avalanche Activity

Significant avalanche activity during the Dec.30-31 storm. Avalanches inland of Thompson Pass proved there is still a dangerous buried weak layer (facets at the ground).

coastal-zone-iconMaritime (Coastal):

  • Dec. 30 Several natural loose avalanches running hundreds of feet in the maritime initiating in steep and rocky terrain to destructive size 2 (D2): Mile High, W of West Peak, S side of Loveland
img_20161230_142630

Loose slide near West Peak & Airport

intermountain-zone-iconInter-Mountain (Transitional):

  • Dec.30 A couple destructive size 2 (D2) storm slab avalanches pulled out on North face of Berlin Wall: stepped down to rocky ground in places (crown depth estimated ~4 feet) and hit the glacier.
  • Dec. 30 Wind loaded south face above Mile Post 37 near 3 Pigs: D2 slab pulled out of steep and rocky rollover and immediately stepped down to ground (see photo)
img_20161230_152840

South facing slab release to ground near 3 Pigs (MP37)

  • Dec.30 South facing steep, rocky gully at Mile Post 42 and ran to aldered apron.

interior-zone-iconContinental (Interior):

  • Dec. 30 D2 storm slab avalanche pulled out to ground mid south slope of Mt Tiekel over Mile Post 46

Dec. 28:

  • Natural D2 slab avalanche on north face of Berlin Wall
  • Natural D1 slab avalanche on south facing roll-over below Little Girls
  • Snowmachine Triggered Avalanche below Catchers Mitt in photo below: photo credit: Eric Christensen

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  12 / 36
Ridgetop Wind Forecast (mph): N / 2-30
Snowfall (in):  0
WIND & TEMPERATURE
past 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction 5 / Var 20 / NE
Max Wind Gust (mph) / Direction 13/ ENE 35 / NE
Temperature Min / Max (*F) 30 / 33 10 / 24

Weather Forecast: A ridge of high pressure will provide mostly clear sky. Outflow north wind to 30mph in passes and ridgetops. Temperature near the coast in the twenties, interior of Thompson Pass near or below zero fahrenheit. If the north wind lays down, expect an inversion that could spike upper elevation temperatures to near freezing.

Additional Info & Media

SNOW HISTORY: Valdez 1/1 AM Thompson Pass 1/1 AM
24 Hour Snow / Water Equiv. 0” /0.0” 0″ /0″
Storm Snow /Water Equiv. (12/30-12/31) 5” /0.68″ 16″ /1.5″
Current Snow Depth 32″ 35″
December Snow / Water Equiv. 73.5″ /4.1″ 69″ / 6″
Total Winter Snowfall / Water Equiv. 95.9″ / 8.16” 140″ / 14.3″
Snowload in Valdez 23 lbs/sq. ft.

img_20161228_130954img_20161228_130730

Photos of our new Nicks Valley Weather Station Python to the east, Berlin Wall to the west.

SNOWFALL for LAST 24 HRS at OTHER STATIONS:
Nicks Valley at 4200 ft (in): 0″
Upper Tsaina at 1750 ft (in): 0″
Sugarloaf at 550 ft (in): 0″
SNOW DEPTH & WATER SURVEY (12/6/2016) Depth Snow Water Equivalent
Milepost 2.5 Valdez  13.2″  2.3″
Milepost 18 15.4″ 2.1″
Milepost 29 Worthington Flats 32.2″ 6.4″
Milepost 37 Tsaina River bridge 24.1″ 4.1″
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.
Sarah Carter

Forecaster: Sarah Carter