Wednesday-Saturday 4/19-4/22

Issued: Wed, Apr 19, 2017 at 8AM

Expires: Sat, Apr 22, 2017

If your foot is punching through to the ground, the snow is isothermal and destructive wet avalanches are possible.

Above 2,500ft Moderate

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

WEDNESDAY THURSDAY FRIDAY & SATURDAY

DANGER SCALE

 

 

WET AVALANCHES:
Elevation:
   Below 5500′
Aspect:
   East in AM, South all day, then West in PM
Terrain:
Steep terrain near rocks and vegetation.
Sensitivity:
   Touchy when warmed.
Distribution:
   Specific.
Likelihood (Human Triggered):
  Possible
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

WIND SLAB:
Elevation:   Above 3000′
Aspect:   Southerlies
Terrain: Near ridgelines, rollovers and gully walls.
Sensitivity:   Responsive to Touchy when sitting on sun crust.
Distribution:   Specific.
Likelihood (Human Triggered):  Possible
Size:   Small
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

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION:

Maritime (Coastal) Specific: The ambient air temperature has hovered around 32 degrees during the heat of the day at 3000′. We have the north winds to thank for keeping things cool. With out these winds the avalanche danger would be rated either considerable, or even high in the afternoons. The winds are forecasted to die down this afternoon and tomorrow, and we are right on the brink of raising the danger level in the afternoons. That being said, it is important you monitor the snowpack and think about how the wind is affecting the terrain you are in. Ask your self, “Are the winds keeping the snow around and above me cold?”. It is all about finding that right balance when the snow has just softened up and hasn’t turned into complete mashed potatoes(isothermal). Cornices are also coming down during this time of year, which could bring the whole season’s snowpack with them, so look out. And don’t forget about the high elevation (5000’+) northerly aspects, which are still holding good powder.

Snow transport Wed, Apr 14 from strong NE outflow.

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

Recent Avalanche Activity

Maritime (Coastal) Specific:

  • 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 12: Numerous natural, wet loose avalanches to size D2.5 from Marshall Pass to the port, large running slides down the south faces west of Mineral creek to the flats/sea level. Many running to ground with dirty debris.
  • April 11: With more direct sun, more wet loose releasing out of steep, south aspects entraining snow to D2.5, sometimes to ground

  • 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):  21 / 31
Ridgetop Wind Forecast (direction/mph):  NE / 15-25
Snowfall (in/water equivalent):  0″ / 0″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  7 / E  18 / NE
Max Wind Gust (mph) / Direction  17 / E  31 / NE
Temperature Min / Max (*F)  33 / 48  23 / 32

Weather Forecast: On the pass, winds have kept the daily high temperatures hovering around the freezing level. At night the temps are still dropping below zero, locking everything at night for the next day. The winds are forecasted to slowly die down today and tomorrow, which will increase temperatures.

Additional Info & Media

SNOW HISTORY: Valdez 4/18 AM Thompson Pass 4/19 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 17″ 39″
April Snow / Water Equiv. trace″ /1.82″ rain 8″ / 0.8″
Total Winter Snowfall / Water Equiv. 239.8″ /24.47” 327″ / 31.4″
Snowload in Valdez 65.0 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (4/17 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.
Kyle Sobek

Forecaster: Kyle Sobek