Tuesday – Friday 3/28-31

Issued: Tue, Mar 28, 2017 at 10AM

Expires: Fri, Mar 31, 2017

8” of new snow and more on the way. The likelihood of starting an avalanche is rapidly increasing. The road run can, has, and will avalanche.

Avalanche Center Tsaina Lodge Spring Full Moon Bon Fire FUNraiser

Friday April 14 presenting Acoustic Avalanche

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

TUESDAY WEDNESDAY THURSDAY & FRIDAY

DANGER SCALE

 

STORM SLAB

Elevation: All
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Widespread
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Increasing
Forecaster Confidence: Good

WIND SLAB:

Elevation:   Above 2000′
Aspect:  Lee to northerly and easterly winds
Terrain:   Near ridges, gullies, rollovers
Sensitivity:   Responsive
Distribution:   Specific
Likelihood (Human Triggered):   Possible
Size:   Small – Large
Danger Trend:   Increasing
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

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION:

Maritime (Coastal) Specific: 

With 8” of new snow in town and on the pass, storm and wind slab avalanches are our primary concern. Before this storm, there was enough cold and clear weather to produce a hoar frost (surface hoar) layer in certain areas. Buried hoar frost is the perfect weak layer for the new snow to avalanche on. Ask your self, ” how is the new snow is bonding to the old snow, and is the new snow settling enough to form a cohesive slab that I can hold in my hands?”

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: 

  • Expect fresh windslab/stormslab to be sensitive, especially where it is building on old hard surfaces
  • 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):  29 / 29
Ridgetop Wind Forecast (direction/mph):  E / 0-25
Snowfall (in/water equivalent):  9-13″ / 1.15″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  5 / NE  19 / SE
Max Wind Gust (mph) / Direction  13 / NE  35 / SE
Temperature Min / Max (*F)  26 / 31  13 / 22

Weather Forecast:  This storm is coming in stronger than expected with up to 13” of snow predicted over the next 24 hours, and up to 2 feet of snow forecasted for the rest of this week. Today, temperatures should stay below freezing at sea level, but later this week expect warming temperatures and rising snow levels. The winds are shifting from northeast to southeast which is important to keep in mind when thinking about wind loaded slopes.

Additional Info & Media

SNOW HISTORY: Valdez 3/28 AM Thompson Pass 3/28 AM
24 Hour Snow / Water Equiv.  9.75”/.58″ 8″ /0.8″
Storm Snow /Water Equiv. (3/27)  10.53″ /.00″ 10″ /1.0″
Current Snow Depth 44.85″ 39″
March Snow / Water Equiv. 10.92″ /.62″ 21″ / 1.4″
Total Winter Snowfall / Water Equiv. 233.8″ /21.54” 304″ / 29.1″
Snowload in Valdez 52.0 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (3/27 AM)/STORM TOTAL (3/27)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 3″ / 3″ / 0.3″
Upper Tsaina at 1750 ft (in): 2″ / 2″ / 0.2″
Sugarloaf at 550 ft (in): 0.1″/ 0.1″ / 0.01″
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.
Kyle Sobek

Forecaster: Kyle Sobek