Monday-Thursday 2/27-3/2

Issued: Mon, Feb 27, 2017 at 8AM

Expires: Thu, Mar 02, 2017

Although the overall rating is low hazard, human triggered avalanches are expected at wind loaded peaks and ridges affected by northerly outflow winds.

Above 2,500ft Low

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

MONDAY TUESDAY WEDNESDAY & THURSDAY

DANGER SCALE

 

WIND SLAB:
Elevation:   Above 2500″
Aspect:  Lee to northerly winds
Terrain:   Near ridges, gullies, rollovers
Sensitivity:   Responsive
Distribution:   Specific
Likelihood (Human Triggered):   Possible
Size:   Small – Large
Danger Trend:   Increasing
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

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION:

Maritime (Coastal) Specific: 

Northerly winds are drifting what snow is available for wind transport on exposed peaks and ridges.

The clear and cold of February 18-22 created widespread surface hoar and near surface facets.

Crudbusters Surface Hoar to 6mm

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: 

  • 2/13-14: Numerous wet avalanches below the rain line (+-3000′) 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):  0 / 25
Ridgetop Wind Forecast (direction/mph):  NE / 20-45
Snowfall (in/water equivalent):  0.5″ / 0.01″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  7 / NE  25 / NE
Max Wind Gust (mph) / Direction  10 / NE  35 / NE
Temperature Min / Max (*F)  40 / 25  10 / 20

Weather Forecast:     Sunny Monday morning becoming overcast with clouds producing only one snowflake. Broken skies Tuesday and Wednesday. Slowly dropping temperatures after Monday into the single digits by Thursday and well below zero north of Thompson Pass. Northerly outflow winds increasing in intensity to above 60 mph Tuesday and Wednesday.

Additional Info & Media

SNOW HISTORY: Valdez 2/27 AM Thompson Pass 2/28 AM
24 Hour Snow / Water Equiv.  0”/0″ 0″ /0″
Storm Snow /Water Equiv. (2/23)  0” /0″ 2″ /0.1″
Current Snow Depth 48″ 42″
February Snow / Water Equiv. 44.9″ /5″ 44″ / 5.1″
Total Winter Snowfall / Water Equiv. 222.8″ /20.9” 283″ / 27.7″
Snowload in Valdez ~ lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (2/24 AM)/STORM TOTAL (2/22-23)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 0″ / 0″ / 0″
Upper Tsaina at 1750 ft (in): 0″ / 0″ / 0″
Sugarloaf at 550 ft (in): 0″/ 0″ / 0″
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.
Pete Carter

Forecaster: Pete Carter