Friday-Monday 1/5-1/8

Issued: Fri, Jan 05, 2018 at 8AM

Expires: Mon, Jan 08, 2018

Above 2,500ft Considerable

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

FRIDAY SATURDAY SUNDAY & MONDAY

DANGER SCALE

WIND SLAB:
Elevation:
   Above 2000 feet elevation
Aspect:  
 Lee to southerly wind during New Years storm AND new windslabs created with clear weather northerly outflow winds Thursday January 4.
Terrain: 
  All terrain exposed to wind
Sensitivity:
   Stubborn
Distribution:   
Specific
Likelihood (Human Triggered):   
Possible
Size:   
Small – Large
Danger Trend:
   Steady 
Forecaster Confidence:
   Fair

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:
The big concern is the near surface faceting <info here> and surface hoar now buried by the New Year’s storm snow. See Observations <here>; many thanks to those submitting for which we’re all much obliged.

Two to four feet of storm snow accumulated since the New Year. During the storm strong southerly winds drifted windslabs to waist deep at Thompson Pass. Following the storm northerly outflow winds redistributed the new snow creating new windslabs over wind exposed terrain.

A few small storm slab releases have been observed along the highway through the inter-mountain snow climate zone, with the releases running on the Boxing Day surface hoar.

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

Reports of (unintentional?) human triggered cornice releases Thursday January 4.
Tuesday and Wednesday January 2nd and 3rd had numerous windslabs to size D2 ran on slopes near the highway over Thompson Pass as well as a few small wet releases in Keystone Canyon. Limited observations. See Observations <here>, including human triggered releases on Road Run.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  10 / 20
Ridgetop Wind Forecast (direction/mph): NE / 10-50
Snowfall (in): 0
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   ~ / ~  30 / NE
Max Wind Gust (mph) / Direction  ~ / ~  50 / NE
Temperature Min / Max (*F)  ~ / ~  12 / 22

Weather Forecast:    Sunny Friday.  Clouds returning over the weekend with snow starting Saturday depositing 2-4″ by nightfall Monday. Outflow northerly winds strongest during the clear weather, decreasing Monday. Skies clearing again next week.

Additional Info & Media

SNOW HISTORY: Valdez 1/3 AM Thompson Pass 1/3 AM
24 Hour Snow / Water Equiv. 0”/ 0.43″ 5″ / 0.2″
Storm Snow /Water Equiv. (1/1) ” / ″ 24″ / 2.5″
Current Snow Depth 25″ 78″
January Snow / Water Equiv. 10″ /2.82 ″ 24″ / 2.5″
Total Winter Snowfall / Water Equiv. 74″ / 19.12” 231″ / 26.7″
Snowload in Valdez 42 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS / STORM TOTAL / STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): ~” / ~” / ~”
Upper Tsaina at 1750 ft (in): ~” / ~” / ~”
Sugarloaf at 550 ft (in): ~” ~” / ~”
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.
Pete Carter

Forecaster: Pete Carter