Sunday-Wednesday 2/19-22

Issued: Sun, Feb 19, 2017 at 8AM

Expires: Wed, Feb 22, 2017

The danger rating has been lowered from “Considerable” to “Moderate” which does not mean green light. Areas like “North Odyssey” or the “Berlin Wall” still have good chance of releasing some sort of avalanche that could take you in/over a terrain trap.

Remember to ALWAYS use travel techniques to your advantage, don’t expose your self if you don’t have to. Ski/Highmark one at a time!

Above 2,500ft Moderate

1,800 to 2,500ft Low

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

SUNDAY MONDAY TUESDAY&WEDNESDAY

DANGER SCALE

 

LOOSE SNOW:
Elevation: All
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Wide Spread
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Steady
Forecaster Confidence: Fair

WIND SLAB:
Elevation: Above 2000″
Aspect: Lee to SE wind
Terrain: Near ridges, gullies, rollovers
Sensitivity: Responsive
Distribution: Specific
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Decreasing
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, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION:

Maritime (Coastal) Specific: 

Dust on crust below +-3000 from the massive rains we had last week. Snowpack is locked up with this cold weather below the rain line.

Expect large amounts (4+ feet) of new snow above that rain line, with wind drifting above the alders. Take 4 feet of new snow, add some wind, and a trigger(like a human) and you have a recipe for an avalanche.

Watch the sunny south facing aspects in the afternoon for some roller balls that could lead to sluff (loose snow) avalanches. These can be deadly if you are brought in/over a terrain trap.

 

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

Maritime (Coastal) Specific: 

  • Numerous wet avalanches below the rain line (+-3000′) during last weeks storm around the port
  • 2/18 Natural sluff avalanches (loose snow) observed on sunny south facing aspects from solar radiation

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  15 / 22
Ridgetop Wind Forecast (direction/mph):  VAR / 0-5
Snowfall (in/water equivalent):  0″ / 0″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  5 / NE  15 / S-NE
Max Wind Gust (mph) / Direction  12 / NE  18 / NE
Temperature Min / Max (*F)  21 / 35  13 / 24

Weather Forecast:  Mostly sunny skies combined with temperature inversions and light, variable winds today. Some possible cloud coverage here and there over the next few days with the arrival of some light flurries. NOAA is calling for a 30% chance of snow on Monday and Tuesday.

Additional Info & Media

SNOW HISTORY: Valdez 2/20 AM Thompson Pass 2/19 AM
24 Hour Snow / Water Equiv. 0”/0″ 0″ /0.0″
Storm Snow /Water Equiv. (2/17-2/18) 3.1” /0.2″ 3″ /0.3″
Current Snow Depth 51″ 49″
February Snow / Water Equiv. 44.2″ /4.5″ 42″ / 5.0″
Total Winter Snowfall / Water Equiv. 222.2″ /20.4” 281″ / 27.6″
Snowload in Valdez 78 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (2/17 AM)/STORM TOTAL (2/17)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 2″ / 3″ / 0.3″
Upper Tsaina at 1750 ft (in): 2″ / 3″ / 0.3″
Sugarloaf at 550 ft (in): 6″/ 7″ / 0.6″
SNOW DEPTH & WATER SURVEY (2/1/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.5″  9.8″
Milepost 18 43.9″ 9.5″
Milepost 29 Worthington Flats 61.5″ 16″
Milepost 37 Tsaina River bridge 42.1″ 9.3″
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 Maritime Forecasts.
Kyle Sobek

Forecaster: Kyle Sobek