Thursday-Sunday 1/26-1/29

Issued: Thu, Jan 26, 2017 at 8AM

Expires: Sun, Jan 29, 2017

Given moderate southerly winds, poor visibility and the continued building of storm slabs with rain in the lower elevations today, choose terrain you are familiar with.

Don’t linger below avalanche paths hanging above you or enter steep terrain without a plan and idea of the snow’s stability. This will be changing quickly today as more weight is added to the stability equation.

Rain on new snow can quickly trigger large and unpredictable avalanches.

Above 2,500ft High

1,800 to 2,500ft High

Below 1,800ft High

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

STORM SNOW:
Elevation:
 All
Aspect: 
All
Terrain: 
Steeper than 35 degress
Sensitivity: 
Reactive
Distribution: 
Widespread
Likelihood (Human Triggered): 
Likely
Size: 
Small – Large
Danger Trend:
 Increasing 
Forecaster Confidence: 
Good

WET AVALANCHES:
Elevation:
 Below 2000′
Aspect: All
Terrain:
>30 degrees
Sensitivity:
 Responsive
Distribution:
 
Widespread
Likelihood (Human Triggered): 
Possible
Size:
 Small-Large
Danger Trend:
 Increasing with rain
Forecaster Confidence: 
Fair

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): 
Unlikely
Size: 
Small – Large
Danger Trend: 
Increasing with load
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: The extreme northerly outflow wind events of January 6 and 18 have left Thompson Pass and most of the upper elevation terrain wind scoured. The new snow of January 23 came in very cold and lays on various bed surfaces of faceted sugar old snow, surface hoar, and windslab. On Tuesday, the northerly outflow winds shifted to the south.

Another 4-6 inches fell in the last 24 hours with moderate onshore SE winds. Given warmer frontal air, expect sticky, soft slabs of storm snow to rest on weaker snow crystals underneath.

 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

Roofs are a slidin’….if they’re steep enough that is.

coastal-zone-iconMaritime (Coastal):

  • Widespread wet snow releases Jan 26 below the rain line. Storm snow instabilities Jan 25.

intermountain-zone-iconInter-Mountain (Transitional):  

  • No new observations.

interior-zone-iconContinental (Interior):  

  • No new observations.

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  28 / 30
Ridgetop Wind Forecast (direction/mph): SE / 5-30
Snowfall (in):  3-10
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   2 / var  20 / ESE
Max Wind Gust (mph) / Direction  7 / NE  27 / SE
Temperature Min / Max (*F)  31 / 35  24 / 30

Weather Forecast:     Despite above freezing temperatures in town, snow has hung on as the form of water falling from the atmosphere. That could change to rain up to 1000′ today as temperatures could peak in the mid 30’s with afternoon precipitation. Expect varied precipitation with slightly cooling temperatures into Friday when a slight wave of snow could hit us. The higher elevations on Thompson Pass will be all snow with up to 10 inches of snow and winds from the SE.

Additional Info & Media

SNOW HISTORY: Valdez 1/26 AM Thompson Pass 1/26 AM
24 Hour Snow / Water Equiv. 8.6” /0.7″ 4″ /0.4″
Storm Snow /Water Equiv. (1/23-26) 24.6” /1.6″ 17″ /1.4″
Current Snow Depth 50.7″ 39″
January Snow / Water Equiv. 71.4″ /4.8″ 71″ / 5.6″
Total Winter Snowfall / Water Equiv. 167.5″ / 14.7” 214″ / 20″
Snowload in Valdez 44.72 lbs/sq. ft.

 

SNOWFALL for LAST 24 HRS at OTHER STATIONS:
Nicks Valley at 4200 ft (in): 6″
Upper Tsaina at 1750 ft (in): 2″
Sugarloaf at 550 ft (in): 9″
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″
Milepost 37 Tsaina River bridge 33.8″ 5.6″
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