Thursday-Sunday 3/22-3/25

Issued: Thu, Mar 22, 2018 at 8AM

Expires: Sun, Mar 25, 2018

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

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

Thursday Friday Saturday
& Sunday

DANGER SCALE

 

WIND SLAB:
Elevation:   Above 1000′
Aspect:   Lee of ridges, gullies, ridgetops
Terrain:   All terrain exposed to northerly winds
Sensitivity:   Responsive
Distribution:   Specific
Likelihood (Human Triggered):   Likely
Size:   Small – Large
Danger Trend:   Steady
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 snow surface is mostly firm with textures varying from undulating sastrugi to tiny patches of softer wind effected snow.  The newly forming wind slabs lee of ridges and gullies continue to develop and give responsive test results.  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.

Check out our public observations <here>

Recent Avalanche Activity

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.
March 17: D2 Wind slab, upper elevation, north aspect inter-mountain snow climate zone, accidental human triggered one foot deep, 30 feet wide, ran 450 feet.

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F): 8 / 18
Ridgetop Wind Forecast (direction/mph): NE / 50-80
Snowfall (in):  0″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  20 / NE   62 / NE
Max Wind Gust (mph) / Direction  54 / NE  89 / NE
Temperature Min / Max (*F)  30 / 34  13 / 18

Weather Forecast:    Clear skies and strong to extreme northerly winds continue through Friday. Temperatures dropping to single digits overnight and raising into the twenties during the day.

Additional Info & Media

SNOW HISTORY: Valdez 3/22 AM Thompson Pass 3/22 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 33″ 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