Sunday-Wednesday 3/11-3/14

Issued: Sun, Mar 11, 2018 at 8AM

Expires: Wed, Mar 14, 2018

Visibility will be in and out today, so plan your route with options for flat light. Avoid fresh windslab on slopes steeper than 30 degrees lee to northerly wind.

Above 2,500ft Considerable

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

Sunday Monday Tuesday
& Wednesday



Elevation:   Above 2000′
Aspect:   Lee of ridges, gullies, ridgetops
Terrain:   Upper elevation terrain exposed to wind
Sensitivity:   Responsive
Distribution:   Specific
Likelihood (Human Triggered):   Possible
Size:   Small – Large
Danger Trend:   Increasing
Forecaster Confidence:   Fair

  30+ degrees steepness
Likelihood (Human Triggered): 
Small – Large
Danger Trend:
Forecaster Confidence:

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



Friday March 9, the advisory area received 5-12″ (12-30cm) of snow. This snow is now being redistributed by northerly wind. Expect fresh windslab on leeward slopes.

Extreme winds  Feb. 28 – Mar. 1 scoured exposed terrain and eroded into older snow layers.  The snowpack depth varies widely due to these wind events scouring the snowpack down to rock and heather, while lee of ridges, and sometimes quite far down the slope, there are pockets of windslab meters deep.

The combined effect of wind events and fewer storm events this season has produced notable density and depth differences across the advisory area. Inland areas have more snow on the ground this year than in the past several seasons. Intermountain areas have a mixed bag snowpack. Maritime areas are less deep and warm than average.

The cold, clear weather between the 1/15 and 2/13 storms grew a faceted weak layer which the subsequent storm snow did not adhere to very well. We have dropped that weak layer from our primary concerns for now, due to its depth 3-7′ (90-310cm) below most surfaces, and observers not finding it reactive in tests. This is the kind of persistent weak layer that might reactivate at some point or may be a problem in certain areas where the snowpack is quite thin. File it in the back of your mind as something to check if you are digging to identify layers.


Recent Avalanche Activity

Two natural D1 windslab avalanches observed near miles 23 and 25 of the road corridor on Friday.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F): 19 / 24
Ridgetop Wind Forecast (direction/mph): NE /10-30
Snowfall (in):  2-9″
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  7 / Variable   18 / NE
Max Wind Gust (mph) / Direction  17 / ENE  37 / NE
Temperature Min / Max (*F)  26 / 36  15 / 21

Weather Forecast:   Partly cloudy with NE wind to 30mph Sunday morning. Scattered snow flurries accumulating up to 8 inches at Thompson Pass through Monday. With a warm front pulling from the tropics, expect warming temps Tuesday with rain at sealevel.

Additional Info & Media

SNOW HISTORY: Valdez 3/11 AM Thompson Pass 3/11 AM
24 Hour Snow / Water Equiv. 0”/ 0″ 1″ / 0.1″
Storm Snow /Water Equiv. (3/9-10) 6.3” / 0.41″ 14″ / 0.9″
Current Snow Depth 37″ 69″ wind scoured
March Snow / Water Equiv. 9.3″ / 0.55″ 16″ / 1.1″
Total Winter Snowfall / Water Equiv. 120.84″ / 24.92” 339″ / 34″
Snowload in Valdez 47 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:



  • 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


Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)


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:

Posted in Continental Forecasts, Intermountain Forecasts, Maritime Forecasts.
Sarah Carter

Forecaster: Sarah Carter