Tuesday-Friday 1/17-1/20

Issued: Tue, Jan 17, 2017 at 8AM

Expires: Fri, Jan 20, 2017

With 54 inches of new snow, wind drifted in north and west start zones, travel in avalanche terrain requires care.

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

TUESDAY WEDNESDAY THURSDAY & FRIDAY

DANGER SCALE

WIND SLAB:
Elevation:
 Above 1800′
Aspect: North – West
Terrain:
Slopes steeper than 30 degrees, loaded by SE wind
Sensitivity:
 Responsive
Distribution:
 
Specific
Likelihood (Human Triggered): 
Likely
Size:
 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 storms deposited 54 inches at Thompson Pass and 45 inches in Valdez. There was a temperature spike Saturday January 14 that brought rain at sea level. There is a lot of uncertainty with the snowpack. We had widespread weakness at the ground before the extreme wind of January 6 as evidenced by the spooky large release west of Milepost 33. The January 13th storm came in cold and built weaker low density snow under the warming slab formed on the 14th. The storm ended with strong southerly winds which moved a lot of the new snow over exposed terrain.

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

Recent Avalanche Activity

Poor visibility prevented new avalanche observations.

coastal-zone-iconMaritime (Coastal):

  • Reports Sunday 1/15 of possibly hearing avalanche activity near East Peak. Avalanches reported in Mineral Creek Saturday 1/14.

intermountain-zone-iconInter-Mountain (Transitional):  Poor visibility did not allow for observations.

interior-zone-iconContinental (Interior):

  • Poor visibility limited new observations.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  0 / 20
Ridgetop Wind Forecast (direction/mph): S / 15
Snowfall (in):  0″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   10/ var  20 / var
Max Wind Gust (mph) / Direction  26 / S  40 / SE
Temperature Min / Max (*F)  23 / 32  10 / 30

Weather Forecast: After a power flurry with little or no further accumulation, the storm is over. The sun will shine, mostly Wednesday and Thursday. Temperatures will drop to -20F and the winds will howl to 50 mph. Beautiful. Tough.

Additional Info & Media

SNOW HISTORY: Valdez 1/17 AM Thompson Pass 1/17 AM
24 Hour Snow / Water Equiv. 3.54” /0.68” 9″ /0.5″
Storm Snow /Water Equiv. (1/13-1/17) 46.78” /3.19″ 54″ /4.2″
Current Snow Depth 44.41″ 39″ (wind scoured)
January Snow / Water Equiv. 46.78″ /3.19″ 54″ / 4.2″
Total Winter Snowfall / Water Equiv. 44.85″ / 13.01” 197″ / 18.6″
Snowload in Valdez 27.56 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): ~5″
Upper Tsaina at 1750 ft (in): ~3″
Sugarloaf at 550 ft (in): ~3″
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.
Pete Carter

Forecaster: Pete Carter