Saturday-Tuesday 3/24-3/27

Issued: Sat, Mar 24, 2018 at 8AM

Expires: Tue, Mar 27, 2018

Above 2,500ft Moderate

1,800 to 2,500ft Moderate

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

Saturday Sunday Monday
& Tuesday
2-moderate 2-moderate 2-moderate

DANGER SCALE

 

WIND SLAB:
Elevation:   Above 1000′
Aspect:   Lee of ridges, gullies, ridgetops
Terrain:   All terrain exposed to northerly winds
Sensitivity:   Stubborn
Distribution:   Specific
Likelihood (Human Triggered):   Possible
Size:   Small – Large
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

LIST OF AVALANCHE PROBLEMS <here>

SNOWPACK DISCUSSION:

The snow surface is mostly firm with textures varying from undulating sastrugi to tiny patches of softer wind effected snow.  The wind slabs lee of ridges and gullies are slowly adjusting to the new load, and on slopes above 35< are still sensitive to human trigger.  In our recent test pits above 3000′ where wind slab is not formed, the top meter (3′) of snow is showing no signs of propagation.

In anticipation of our next snow cycle – If our next snowfall comes in relatively cold and light, it may not create a strong bond with the current snow surface.

With moderate temperatures and the spring sun being more intense now, any rapid warming of surface snow could create instabilities.  If you see signs of rapid warming (“roller balls”,”pinwheels”, wet avalanches),  it’s best to go elsewhere.

Check out our public observations <here>

Recent Avalanche Activity

March 22: D2 wind slab on S facing slope at 3500′ near milepost 29

March 21: Natural wind slabs to size D2, including onto the highway at Milepost 23.
March 19-20: Numerous natural wind slab releases to size D2 observed between Mileposts 22 and 29 across Thompson Pass with the initial onset of the present extreme northerly wind event, transporting available soft snow.

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F): 12 / 20
Ridgetop Wind Forecast (direction/mph): NE / 15-35
Snowfall (in):  0″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  8 / NE   27 / NE
Max Wind Gust (mph) / Direction  23 / EME  49 / NE
Temperature Min / Max (*F)  29 / 38  11 / 20

Weather Forecast:    Clear skies Saturday and Sunday. Variable winds light to moderate.  Upper elevation temperatures dropping to 10*F overnight and raising into the twenties during the day.  The port of Valdez will see temperatures around freezing during the day.  Chance of precipitation on Monday and Tuesday.

Additional Info & Media

SNOW HISTORY: Valdez 3/24 AM Thompson Pass 3/24 AM
24 Hour Snow / Water Equiv. 0”/ 0.0″ 0″ / 0.0″
Storm Snow /Water Equiv. (3/9-14) 19” / 0.41″ 40″ / 1.5″
Current Snow Depth 32″ 84″
March Snow / Water Equiv. 20.5″ / 2.61″ 49″ / 3.6″
Total Winter Snowfall / Water Equiv. 132.59″ / 27.2” 372″ / 36.6″
Snowload in Valdez 55 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