Thursday-Sunday 1/5-1/8

Issued: Thu, Jan 05, 2017 at 8AM

Expires: Sun, Jan 08, 2017

Bundle up for the upcoming winds chills and look out for new, touchy wind slab formations with extreme snow transport starting this afternoon/evening.

2017 New Year’s resolution – develop backcountry habits to LIVE TO RIDE ANOTHER DAY:

  • everyone is my riding group has a functioning beacon, probe, and shovel (& floatpack)
  • my group chooses to avoid slopes with rocky trigger points 
  • my group chooses to avoid slopes with terrain traps; cliffs, gullies, and creek ravines
  • my group agrees that one rider on a steep slope at a time is what we do
  • my group gathers out of harm’s way, beyond the run-out
  • my group reviews our day – where could we have triggered a slide? how can we improve our plan? 

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

DANGER SCALE

WIND SLAB:
Elevation: Above 1800′
Aspect: mostly south and west
Terrain: Near ridgelines, gullies and rollovers
Sensitivity: Responsive
Distribution: Specific
Likelihood (Human Triggered): Possible
Size: Small to Medium
Danger Trend: Increasing
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: 
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, Medium, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor

LIST OF AVALANCHE PROBLEMS <here>

SNOWPACK DISCUSSION: Scouring and flagging returned Wednesday afternoon as winds began to pick up out of the NE. Look for drifting of all loose, dry snow and loading of slopes protected from the expectant gale force winds the next couple of days. These new wind slabs will add snow load and test weaker snow structures that are thinner and colder….found generally further from the coast.
coastal-zone-iconMaritime (Coastal):
This region is generally harboring a thicker snowpack in the upper elevations that has seen consistently warmer temperatures…especially the last few days. This combination has resulted in a stronger, more predictable snow structure. The most recent avalanche activity has only involved the newest, surface snow. If you can navigate your way through the alders in the lower elevations, enjoyable conditions can be found.

intermountain-zone-iconInter-mountain (Transitional):
A large variance in depth and structure dominates this region. Weak, early season facets at the ground and between layers of windslab remain a concern, especially in steep, shallow and unsupported snowfields. Many of the storms this season have not pushed interior very far, so areas further from the ocean are generally thinner and more questionable. It has been colder on the interior side as well. These circumstances support persistent weaknesses that have been showing themselves thoughout the inter-mountain region. In the upper Tsaina Valley and north of Mile Post 36 along the highway corridor, the snow is reacting very similar to the continental region: weak, shallow structure that fails easily when loaded.

interior-zone-iconContinental (Interior):
More interior beyond Mile Post 46 and out past Billy Mitchell, the snowpack is thin and incredibly weak: mostly facets. Recent avalanches are readily stepping down to ground. This region will require significant amounts of new snow and an avalanche cycle to turn things around.

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

Recent Avalanche Activity

Please report avalanches you see or trigger. The Valdez Avalanche Center does not dwell on the who or why an avalanche incident may have occurred, but want to be informed about what the snow is doing out there. There is uncertainty about the persistent slab problem right now and any activity or signs of unstable snow provides more clues for forecasting the patterns in our area. This benefits all of us who recreate in this region.

coastal-zone-iconMaritime (Coastal):

  • A couple new loose size 1-2 avalanches out of steep rocks Jan.2 above 3000′.

intermountain-zone-iconInter-Mountain (Transitional): 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) that has a lower probability of triggering, but high consequence due to hard windslab to 2-3 feet overtop.

  • Jan. 4: Three, size 2, south facing, slab avalanches seen looking up the Tsaina Valley: One failed on a broad face, mid slope, while the other two crowns were near a rocky, steep ridgeline.
  • Jan.1 Two size 2 slab avalanches released to ground above MP 36, south aspect above 3000′
  • Dec.31 A couple human triggered destructive size 1-2 windslab avalanches on the steep slopes of the road run
  • 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)
  • 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

 

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  -5/ 22
Ridgetop Wind Forecast (direction/mph): NE / 10-70
Snowfall (in):  0
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction 4 / NNE 30/ NE
Max Wind Gust (mph) / Direction 27/ NE 52 / NE
Temperature Min / Max (*F) 22 / 44 8 / 26

Weather Forecast: As the dominating high pressures slowly shifts northeast, expect interior arctic air to force its way to the coast with gale forces reaching 90mph starting this evening through Saturday morning. This is will stir up the pools of low-lying cold air, killing the inversion that has been dominating our region. Initial warming will give way to cold temperatures that top out near zero on Thompson Pass. No moisture is seen in the near future.

Additional Info & Media

SNOW HISTORY: Valdez 1/4 AM Thompson Pass 1/4 AM
24 Hour Snow / Water Equiv. 0” /0.0” 0″ /0″
Storm Snow /Water Equiv. (12/30-12/31) 5” /0.68″ 18″ /1.6″
Current Snow Depth 29.5″ 31″
January Snow / Water Equiv. 0″ /0″ 0″ / 0″
Total Winter Snowfall / Water Equiv. 95.9″ / 8.16” 143″ / 14.4″
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 (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″  Jan.3
Milepost 37 Tsaina River bridge 33.8″ 5.6″  Jan.3
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.

Forecaster: Kevin Salys