Friday-Monday 4/13-4/16

Issued: Fri, Apr 13, 2018 at 8AM

Expires: Mon, Apr 16, 2018

Spring Fundraiser tonight, April 13, at Tsaina Lodge! Door prizes! Silent auction!

Acoustic Avalanche and Jer Ber playing music!  See you there!

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

Friday Saturday Sunday & Monday
 

DANGER SCALE

Wet Avalanches:
Elevation:   Below 4000′
Aspect:   SE – S – SW
Terrain:   Southerly facing terrain on slopes above 30 degree slope angle
Sensitivity:   Non-reactive – Responsive as sun and warmer temperatures dominate
Distribution:   Specific
Likelihood (Human Triggered): Possible
Size:   Small 
Danger Trend:   Increasing with solar input and warmer temperatures
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

LIST OF AVALANCHE PROBLEMS <here>

SNOWPACK DISCUSSION: The forecast region is on the verge of experiencing a shed cycle, particularly below 3500′.  Temperatures around Thompson Pass have been above freezing during the day, and barely freezing over night.  This cycle can produce corn snow but is also the precursor to surface instability and an isothermic snowpack.

The snowpack below 2500′ is not refreezing at night and is becoming isothermic in many areas, especially on southerly facing slopes.

Snow surface conditions above ~3000′ are variable and range from wind scoured pencil hard sastrugi, sun effected melt/freeze, to decomposing unconsolidated particles.  Below ~3000′ surface conditions range from heavy wet snow, to corn, to isothermal.  Snow depths generally range from 30-300cm.

Check out our public observations!

Recent Avalanche Activity

Numerous southerly facing slopes above 30< slope angle are experiencing natural point release wet avalanches from the port of Valdez up to 3500′ throughout the advisory area.  All of this wet avalanche activity has been surface snow and shown no signs of stepping down deeper into the snowpack.

The conditions we’re experiencing lately don’t fit well with our North American Danger Scale.  We’re at a low danger in the mornings, with natural and human triggered avalanches unlikely. As the day progressively becomes warmer and as solar input increases, the danger increases as the surface warms.  When this happens, small human and natural triggered avalanches could become likely.

Video of Winds from 3/22/18

 

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F): 29 / 37
Ridgetop Wind Forecast (direction/mph): N / 0-12
Snowfall (in):  0”
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  3 / VAR   11 / VAR
Max Wind Gust (mph) / Direction  23 / W  22 / NE
Temperature Min / Max (*F)  31 / 49  27 / 38

Weather Forecast:      Clear skies Friday trending toward cloudy in the evening. Temperatures in the Port of Valdez and at Thompson Pass into the 40’s F (4-9*C).  Light to moderate winds.

Additional Info & Media

SNOW HISTORY: Valdez 4/13 AM Thompson Pass 4/13 AM
24 Hour Snow / Water Equiv. 0”/ 0.0″ 0″ / 0.0″
Storm Snow /Water Equiv. (3/15-19) 19” / 0.41″ 40″ / 1.5″
Current Snow Depth 21″ 64″
April Snow / Water Equiv. 0″ / 0″ 0″ / 0″
Total Winter Snowfall / Water Equiv. 132.59″ / 27.2” 372″ / 36.6″
Snowload in Valdez 53 lbs/sq. ft.

 

SNOW DEPTH & WATER SURVEY (3/4/2018) Depth Snow Water Equivalent
Milepost 2.5 Valdez  32.2″  9″
Milepost 18 42″ 11″
Milepost 29 Worthington Flats 62.4″ 21.2″
Milepost 37 Tsaina River bridge 58.4″ 14.2″
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 Continental Forecasts, Intermountain Forecasts, Maritime Forecasts.

Forecaster: Ryan Van Luit