Thursday – Sunday 3/30-4/2

Issued: Thu, Mar 30, 2017 at 8AM

Expires: Sun, Apr 02, 2017

DOT will be doing avalanche control work from MP 37-42 today! Expect delays.

Another 5 inches of snow tallies up to 23 total at Thompson Pass for this storm cycle.

Limited visibility and unstable snow slabs will complicate travel and terrain selection.

Evaluate the new snow to old snow bonding and mid-storm weaknesses as temperatures have been quite variable throughout the storm.

Friday April 14: VAC Spring Full Moon FUNraiser with Acoustic Avalanche @  Tsaina Lodge

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

 

STORM SLAB:
Elevation: All
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Widespread
Likelihood (Human Triggered): Likely
Size: Small – Large
Danger Trend: Increasing
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

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION:

Maritime (Coastal) Specific: 

An upside down snowpack has developed since temperatures warmed Wednesday, peaking in the high 30s down near the port and mid to high 20s near 3000′. 2 feet of snow has been measured in the port and on Thompson Pass, with more likely in the upper elevations which is colder and dryer. Human triggered avalanches were reported on the road run the last couple of days and slab and wet loose snow was moving on very steep slopes around the port on Wednesday. Maintain vigilance in evaluating the bonding of new snow to old and mid-storm weaknesses that have been failing with a top heavy load.

Find more photos and observations at the bottom of the page. Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

Maritime (Coastal) Specific: 

Poor visibility have limited observations: please share if you have seen anything!!!

  • March 29: 0-1000′ elev. below Comstock: up to 18″ of heavy storm snow was shifting and sliding under foot in steeps with friction: propagation limited
  • March 28: human triggered avalanches on the road run
  • March 25: reports of upper elevation (>4500′ elevation) human triggered windslabs to a foot thick releasing off steep slopes.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  26 / 29
Ridgetop Wind Forecast (direction/mph):  SE / 10-25
Snowfall (in/water equivalent):  5-10″ / 0.7″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  4 / Var  17 / SE
Max Wind Gust (mph) / Direction  21 / W  25 / ESE
Temperature Min / Max (*F)  32 / 37  20 / 28

Weather Forecast:  With slightly cooler temps this morning (high teen on the pass and just below freezing at lower elevations) and a few snowflakes are falling in town, expect a continuation of light snowfall until this evening when volume could pick as the bulk of a front hits us (possible 6 inches overnight). Clouds and light precipitation will persist through the weekend, but temperatures will warm Friday, transitioning the moisture to rain up to 2500′. Not much precipitation will make it interior until Friday when more gusto can push over the range. Winds will remain moderate with the back and forth battle of onshore and offshore flow at mountain passes.

Additional Info & Media

SNOW HISTORY: Valdez 3/30 AM Thompson Pass 3/30 AM
24 Hour Snow / Water Equiv.  0.6”/.44″ 5″ /0.5″
Storm Snow /Water Equiv. (3/27-30)  13.6″ /?” 23″ /2.3″
Current Snow Depth 42.9″ 42″
March Snow / Water Equiv. 14.6″ /1.6″ 34″ / 2.7″
Total Winter Snowfall / Water Equiv. 237.5″ /22.5” 317″ / 30.4″
Snowload in Valdez 52.0 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (3/30 AM)/STORM TOTAL (3/27-30)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 3″ / 10″ / ?”
Upper Tsaina at 1750 ft (in): 1″ / 6″ / 0.8″
Sugarloaf at 550 ft (in): 0.01″/ 15″ / 1.6″
SNOW DEPTH & WATER SURVEY (2/28/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.8″  12″
Milepost 18 42.7″ 11.5″
Milepost 29 Worthington Flats 63.6″ 18.6″
Milepost 37 Tsaina River bridge 49.3″ 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.

Forecaster: Kevin Salys