Wednesday – Saturday 3/22-25

Issued: Wed, Mar 22, 2017 at 8AM

Expires: Sat, Mar 25, 2017

Proceed with caution on wind loaded slopes. Skier triggered avalanches have been reported over the last 48 hours.

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 3-5pm: Recognizing 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

WEDNESDAY THURSDAY FRIDAY & SATURDAY

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: 

Since Monday, Backcountry enthusiasts have been out and about on many different aspects and elevations putting this new snow to the test. There have been numerous reports of natural and skier triggered avalanches over the last few days. It seems these human triggered avalanches are occurring in shallow rocky spots, where people are hitting the perfect, “trigger point”. North winds picked up Tuesday, and are expected to continue this week, which will increase the cohesiveness of the fresh snow, turning it into a stiffer slab giving it a greater potential to avalanche.

Certain Maritime zones have a variation of new snow from the last 48 hours. Cordova reported 8 inches at sea level Monday AM, with 2 feet at 1000′, while the town of Valdez received 2 inches with 1 foot at the pass, and trace amounts of snow at 56 Mile.

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):  3 / 15
Ridgetop Wind Forecast (direction/mph):  NE / 25-45
Snowfall (in/water equivalent):  0″ / 0.0″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  13 / NE  31 / NE
Max Wind Gust (mph) / Direction  17 / NE  40 / NE
Temperature Min / Max (*F)  29 / 34  12 / 17

Weather Forecast: The winds from the north have returned with moderate force, gusts expected to 45MPH through the pass today. Noticeable flagging on peaks observed on Tuesday including: Berlin Wall, Odyssey, Python, Loveland, and many other peaks off the road corridor. Temperatures have dropped to the mid teens at night. There will be flat light with greybird skies, as the low pressure system seems to be moving further south in the Gulf of Alaska. Areas more interior will have better visibility, but with less snow from the last few days.

Additional Info & Media

SNOW HISTORY: Valdez 3/23 AM Thompson Pass 3/21 AM
24 Hour Snow / Water Equiv.  0.0”/.00″ 3″ /0.2″
Storm Snow /Water Equiv. (3/20)  0.0″ /.00″ 1″ /0.4″
Current Snow Depth 37″ 42″
March Snow / Water Equiv. 0.8″ /.03″ 11″ / 0.4″
Total Winter Snowfall / Water Equiv. 223.7″ /20.8” 294″ / 28.1″
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.
Kyle Sobek

Forecaster: Kyle Sobek