Saturday-Tuesday 3/18-21

Issued: Sat, Mar 18, 2017 at 8AM

Expires: Tue, Mar 21, 2017

Incredibly firm and variable conditions warrant more conservative speeds and plans. Monitor persistent weaknesses buried under firm layers.

Come enjoy the VAC Basecamp FREE classes every day this week in the One Love Lot (MP 29.5). Check our Facebook page for more details!

 

Above 2,500ft Low

1,800 to 2,500ft Low

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

DANGER SCALE

 

WIND SLAB:
Elevation:   Above 2000′
Aspect:  Lee to northerly winds
Terrain:   Near ridges, gullies, rollovers
Sensitivity: Stubborn
Distribution:   Specific
Likelihood (Human Triggered): Unlikely
Size:   Small – Large
Danger Trend:   Decreasing
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: 

Recent evaluation in the port area (<1000′) demonstrated that poor structure remains in the upper snowpack: primarily wind slab resting on weak sugar snow (old facets). Test results supported easy collapses and propagation of the knife on fist layer combo. This undesirable situation is a bit less concerning due to the poor quality fracture (Q3) and friction/resistence within the thick, underlying weak layer that is bonding to the bottom of the wind slab. This is only where the wind slab can be found, for the majority of areas have been scoured down to the mid-February rain crust. Human triggered wind slab avalanches are unlikely, but steep, wind protected areas that retain the poor structure should be evaluated. You are most likely to trigger this slab where the snowpack is the thinnest. The last reported human triggered avalanche was March 11th.

There are incredibly limited soft snow options for skiing, snowboarding, or snowmachining in the Valdez region, yet some far off wind protected pockets have held some inconsistent soft snow/facets. Despite a dusting in the interior on Wednesday, Valdez has not seen significant snowfall for one month as of today. 13 of the last 16 days had 50 mph wind gusts, approaching 100 mph at the beginning of this month. This wind cycle has completely scoured and stripped all peaks and ridges of their snow. Glacial ice has been exposed in areas normally visible mid summer. Entrances to many “normal” ski runs are bare rock.

Rain Crust from mid Feb.

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: 

  • Recently reported from Mar 7: 2x D1 AS soft slabs (3500’ SW 20cm and 4000’ NE 15cm), long running dry loose and several collapses on low angle terrain.
  • Somewhat recent wind slabs (likely occured during Mar. 2-3 wind event) had scoured/released to ground near the 3000′ elevation on varying aspects.

Wind slab to ground west of Meteorite. NE aspect at ~3000′

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  -2 / 15
Ridgetop Wind Forecast (direction/mph):  NE / 20-35
Snowfall (in/water equivalent):  Trace / 0.09″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  13 / NE  35 / NE
Max Wind Gust (mph) / Direction  30 / ENE  50 / NE
Temperature Min / Max (*F)  15 / 24  -5 / 7

Weather Forecast:   Wind and temperatures have dropped slightly due to clear skies and the gulf low moving eastward. Today, a weak low will develop that will bring clouds tonight and a possible dusting of snow…nothing substantial. As the clouds clear monday, expect a return to more of the same through the end of the week.

Additional Info & Media

SNOW HISTORY: Valdez 3/18 AM Thompson Pass 3/19 AM
24 Hour Snow / Water Equiv.  0”/0″ 0.2″ /0.01″
Storm Snow /Water Equiv. (2/23)  0″ /0″ 2″ /0.1″
Current Snow Depth 37″ 38″
March Snow / Water Equiv. 0″ /0″ 0.2″ / 0.01″
Total Winter Snowfall / Water Equiv. 222.8″ /20.9” 283″ / 27.7″
Snowload in Valdez ~ lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (3/18 AM)/STORM TOTAL (3/18)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 0″ / 0″ / 0″
Upper Tsaina at 1750 ft (in): 0″ / 0″ / 0″
Sugarloaf at 550 ft (in): 0″/ 0″ / 0″
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:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Thompson Pass RWIS weather station <here>
  • MP 30 Nicks (Happy) Valley weather station at 4200 feet <here> (scroll to Nicks Valley)
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>
  • Further weather resources <here>

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