Monday – Thursday 3/27-30

Issued: Mon, Mar 27, 2017 at 10AM

Expires: Thu, Mar 30, 2017

Pay attention to steep slopes lee of the northerly wind. Windslab will often feel stiffer or have shooting cracks. Avoid windloaded slopes with terrain traps beneath. The danger is increasing with more snowfall and continued wind.

Avalanche Center Tsaina Lodge Spring Full Moon Bon Fire FUNraiser

Friday April 14 presenting Acoustic Avalanche

 

Above 2,500ft Moderate

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

MONDAY TUESDAY WEDNESDAY & THURSDAY

DANGER SCALE

 

 

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: 

While northeast wind transports new storm snow (4-12″), windslabs will build. The question is how will these new slabs adhere to old snow?  March 20th brought 5-24″. That snow was observed to have near surface facets to 2mm, which will function as a weak layer between the newest snow/windslab and the old hard surfaces. Possibility of human triggered slab to 24″ deep on steep rollovers and near ridgetop.

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 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):  10 / 30
Ridgetop Wind Forecast (direction/mph):  NE / 5-40
Snowfall (in/water equivalent):  4-8″ / 0.6″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  8 / NE  26 / NE
Max Wind Gust (mph) / Direction  17 / NE  39 / NE
Temperature Min / Max (*F)  26 / 33  5 / 16

Weather Forecast:   With some cloud moving into the region supported by a low pressure system located south of the Aleutians, we should see some precipitation ~4-8″ snow by Wednesday with possibility of a foot by Thursday (water equivalent of 1/2″). While moderate to strong northeast wind continues, precipitation will not push interior. Temps will trend warmer by mid-week. Visibility expected to be poor or in and out.

Additional Info & Media

SNOW HISTORY: Valdez 3/28 AM Thompson Pass 3/27 AM
24 Hour Snow / Water Equiv.  9.75”/.58″ 2″ /0.2″
Storm Snow /Water Equiv. (3/28)  10.6″ /.00″ 2″ /0.2″
Current Snow Depth 44.8″ 36″
March Snow / Water Equiv. 10.9″ /.62″ 13″ / 0.6″
Total Winter Snowfall / Water Equiv. 233.8″ /21.5” 296″ / 28.3″
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:

  • 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.
Sarah Carter

Forecaster: Sarah Carter