Monday – Thursday 3/20-23

Issued: Mon, Mar 20, 2017 at 8AM

Expires: Thu, Mar 23, 2017

Flat light will reduce your ability to see above and around you. Remember surfaces are hard and inconsistent under the dusting of new snow.

Join the VAC Basecamp FREE classes every day this week in the One Love Lot (MP 29.5). Check our Facebook page for more details! Today’s class: Plan & Prepare for Travel in Avalanche Terrain

 

 

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

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):   Likely
Size:   Small – Large
Danger Trend:   Steady
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: 

A couple inches of new cold snow in the alpine will be blown around creating fresh windslab on hard surfaces. Expect it to be sensitive to human trigger.

Due to the prolonged cold, clear, windy beginning to March, the snowpack structure is weak with lots of facets under and between layers of windslab. Before this new dusting, high ground was stripped bare. Glacial ice is exposed in many areas.

Rain Crust from mid Feb. is now a bed surface.

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 human triggered windslab near ridgetops.
  • March 7 : report of two human triggered size D1 soft slabs (20cm deep on a SW aspect at 3500′ and 15cm deep on a NE aspect at 4000′). Some human triggered dry loose activity to size D1.5. With several collapses felt on low angle terrain.
  • March 2/3 : report of windslabs to size 2 released to ground near the 3000′ elevation on aspects lee to north wind.

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):  10 / 19
Ridgetop Wind Forecast (direction/mph):  E – N / 20-35
Snowfall (in/water equivalent):  1″ / 0.08″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  4 / NE  19 / NE
Max Wind Gust (mph) / Direction  16 / NE  36 / NE
Temperature Min / Max (*F)  20 / 28  0 / 10

Weather Forecast:   Partly clear. Over the next few days, bands of cloud and flurries will pass over our area with not much more snow accumulating. Thompson Pass might see another couple inches, while the interior remains dry. A slight warming trend from yesterday, with temps in the teens fahrenheit near Thompson Pass. East to northeast wind will continue with gusts to 35mph in constricted terrain and passes.

Additional Info & Media

SNOW HISTORY: Valdez 3/20 AM Thompson Pass 3/20 AM
24 Hour Snow / Water Equiv.  0.8”/.03″ 8″ /0.2″
Storm Snow /Water Equiv. (3/20)  0.8″ /.03″ 8″ /0.2″
Current Snow Depth 38″ 45″
March Snow / Water Equiv. 0.8″ /.03″ 8″ / 0.2″
Total Winter Snowfall / Water Equiv. 223.7″ /20.8” 291″ / 27.9″
Snowload in Valdez 62.4 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (3/20 AM)/STORM TOTAL (3/20)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 2″ / 2″ / 0.02″
Upper Tsaina at 1750 ft (in): 0.1″ / 0.1″ / 0.01″
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