Thursday-Sunday 4/27-4/30

Issued: Thu, Apr 27, 2017 at 8AM

Expires: Sun, Apr 30, 2017

Springtime conditions exist: avalanche danger increases with daytime warming and solar radiation.

Expose yourself to avalanche prone terrain only when necessary. Even if you are standing on flat ground, the upper slopes above you are harboring large amounts of weakening snow that could travel great distances if it happens to release.

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

Below 1,800ft Considerable

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

 

 

WET AVALANCHES:
Elevation:
   Below 6000′
Aspect:
   All steep terrain, especially aspects that have direct sun
Terrain:
Slopes >35 degrees near rocks and vegetation.
Sensitivity:
   Touchy when warmed.
Distribution:
   Specific.
Likelihood (Human Triggered):
  Likely when warmed.
Size:
  Small-Large
Danger Trend:
   Increasing quickly each day with warming temperatures, falling with freezing at night
Forecaster Confidence:
   Good

CORNICE FALL:
Elevation: 
ALL
Aspect:   
ALL
Terrain:
corniced ridgelines
Sensitivity:   
Responsive 
Distribution:   
Specific
Likelihood (Human Triggered): 
Possible
Size:  
Small to 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: 

Warm temperatures yesterday led to poor overnight freezing of the snowpack. When you add the weight and weakening properties of rain on snow, natural avalanche activity from above is possible. Wet avalanche can travel greater than expected distances and are incredibly dense and powerful. Limit any exposure to overhanging snow and evaluate the snow underneath you as you travel through the mountains. It may be difficult to see signs of red flag activity when the visibility is poor. If the snow is shifting easily under skis or machine and you can easily sink deep into underlying layers of snow, consider calling it a day. Large, crushing, wet slabs can be triggered quite deep this time of year. There is a chance for some snowflake accumulation up high, but it just depends on the air mixing patterns and wind.

Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

Maritime (Coastal) Specific:

  • April 23 Natural wet slab D2.5 above Deserted Glacier, west aspect, 5800′. Lots of south and west cornice failure and wet loose activity into the Woodworth and Deserted Glaciers.

    April 23: fresh wet slab at 5800′ on west aspect above Deserted Glacier        Photo: Sarah Carter

  • April 17 The Wall/Tomahawk rockfall resulting in D3+ avalanche.
  • April 13-16 More wet loose activity in the afternoon on steep solar affected slopes

  • April 18th  “Things are coming unglued out there” Photo: Jeremy Martin

  • Large avalanche on, “The Wall/Tomahawk” caused by rockfall Photo: Jed Workman

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  32 / 40
Ridgetop Wind Forecast (direction/mph):  SW / 0-10
Snowfall (in/water equivalent):  1″? / 0.18″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  6 / Var  7 / Var
Max Wind Gust (mph) / Direction  13 / WSW  14 / NE
Temperature Min / Max (*F)  38 / 49  31 / 43

Weather Forecast: Warmer air temperatures in the upper elevation peaked at 43*F on Thompson Pass and 49*F above Nicks. There was not much of a freeze besides  the very upper elevations.  Rain will persist into tomorrow, but possibly will break Friday night and into Saturday where some blue may reveal itself if you pray long enough. The longer outlook seems that clouds and precipitation will return on Sunday and well into next week as a similar pattern sets in.

Additional Info & Media

SNOW HISTORY: Valdez 4/24 AM Thompson Pass 4/24 AM
24 Hour Snow / Water Equiv.  0”/0.0″ 0″ /0″
Storm Snow /Water Equiv. (3/26-4/9)  16.9″ /4.1″ 24″ /2.4″
Current Snow Depth 5″ 39″
April Snow / Water Equiv. trace″ /1.82″ rain 8″ / 0.8″
Total Winter Snowfall / Water Equiv. 239.8″ /24.64” 327″ / 31.4″
Snowload in Valdez 65.0 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (4/24 AM)/STORM TOTAL (3/27-4/6)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 0″ / ~16″ / ?”
Upper Tsaina at 1750 ft (in): 0″ / ?” / 1.2+”
Sugarloaf at 550 ft (in): 0″/ 20+rain” / 2.8″
SNOW DEPTH & WATER SURVEY (4/2/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.9″  11.9″
Milepost 18 40″ 11.9″
Milepost 29 Worthington Flats 62.2″ 19.6″
Milepost 37 Tsaina River bridge 46.3″ 12.5″
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 Maritime Forecasts.

Forecaster: Kevin Salys