Get out and enjoy the snow before it blows away or gets compacted into sastrugi or wind board.
Onshore winds and a foot of new snow on Thompson Pass have filled in the landscape, masking undulating, firm surfaces just beneath. Get out on non-consequential features and evaluate how the new snow is bonding with old sugar snow and in between storm layers before moving into steeper terrain.
Lower elevations are filling in and specific features could build enough snow to move, especially with strong winds moving snow around this weekend.
It still is early season: Early season dangers explained here (link to summary by Avalanche Canada).
Above 2,500ft Considerable
1,800 to 2,500ft Considerable
Below 1,800ft Low
Degrees of Avalanche Danger ?
GENERAL DANGER RATING OUTLOOK
|FRIDAY||SATURDAY||SUNDAY & MONDAY|
Elevation: 1800′ and above
Terrain: Steep and onshore wind lee features with drifting snow
Likelihood (Human Triggered): Likely
Size: Small to Medium
Danger Trend: Increasing
Forecaster Confidence: Good
Details: 12 inches of snow has accumulated and drifted with significant SE onshore winds.
WIND & PERSISTENT SLAB:
Elevation: 2500′ and above
Aspect: Mostly south and lee to outflow flow wind, but all suspect
Terrain: Ridgelines, rollovers, crossloaded features
Distribution: Specific features
Likelihood (Human Triggered): Possible
Size: Small to Medium
Danger Trend: Increasing with offshore blowing snow
Forecaster Confidence: Fair
Details: North wind will creat new slabs and add weight and stress on persistent facets (sugar snow) lower in the snowpack.
AVALANCHE PROBLEM SCALE DESCRIPTORS:
Sensitivity: Non-reactive, Stubborn, Responsive, Touchy
Distribution: Isolated, Specific, Widespread
Likelihood: Unlikely, Possible, Likely, Nearly Certain
Size: Small, Medium, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor
LIST OF AVALANCHE PROBLEMS <here>
A foot of new snow (scoured to nothing or drifted to 2+ feet in places) on Thompson Pass and more in the maritime near town is settling in on top of a variety of surfaces: ground, old facets, crust and windslab. The warm storm seems to have allowed the new snow to stick fairly well to these surfaces, but continue to monitor this, especially at higher, colder elevations. Strong onshore winds during the storm have created sensitive interfaces of soft slab that would fail in compression, but didn’t want to support propagation. As northerly, outflow winds return, look for intense snow transport and sensitive new wind slab formation. These will be responsive to human interaction. Lastly, don’t forget about our deeper, persistent facets that lay under some very firm slabs. Give these guys due respect as stress and mass increase on top of them.
Find more photos and observations below: at the bottom of the page. Sharing your observations helps others make informed decisions about where and how to go.
Recent Avalanche Activity
No new avalanche activity observed.
|WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:|
|Temperature Forecast (Min/Max *F):||9/21|
|Ridgetop Wind Forecast (mph):||NE/15-45|
|WIND & TEMPERATURE Past 24 Hours:||Ferry Terminal||Thompson Pass|
|Average Wind Speed (mph) / Direction||0?||27 / SE|
|Max Wind Gust (mph) / Direction||?||38 / NE|
|Temperature Min / Max (*F)||29 / 32||13 / 29|
As a high pressure system returns to the area through the weekend, clear skies, cold temperatures and gusty winds will dominate. Cold air in the interior and a low in the gulf will create temperatures from the single digits to below zero and 50+ mph offshore winds through the passes. Early next week, winds will back and down and clouds and temperatures increase.
Additional Info & Media
|SNOW HISTORY:||Valdez 12/1 AM||Thompson Pass 12/1 AM|
|Current Snow Depth||23″||27″|
|24 Hour Snow / Water Equiv.||11” /0.6″||8″ /0.5″|
|Storm Snow /Water Equiv. (11/30-12/2?)||11” /0.6″||8″ /0.5″|
|November Snow / Water Equiv.||33.3″ / 4.7″||57″ / 6.4″|
|Total Winter Snowfall / Water Equiv.||33.3″ / 4.7”||80″ / 8.8″|
|Snowload in Valdez||5.0 lbs/sq. ft.|
|SNOW DEPTH & WATER SURVEY (date)||Depth||Snow Water Equivalent|
|Milepost 2.5 Valdez||?″||?″|
|Milepost 29 Worthington Flats||?″||?″|
|Milepost 37 Tsaina River bridge||?″||?″|
|This survey is done the first week of each month beginning in December.|
- 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:
- Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
- Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
- Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Photo of Thompson Pass <here>
Map of Valdez Forecast areas and recreating zones <here> (Thank you Trevor Grams!)
Run map of some of the forecast area <here>
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.