Wednesday-Saturday

Issued: Wed, Nov 30, 2016 at 8AM

Expires: Sat, Dec 03, 2016

Tune in to KCHU this morning, Wednesday 9-10am for Coffee Break with Valdez Avalanche Center.

If you adventure into the alpine, pay attention to how the snow sounds and feels. If it begins to get punchy or sounds like a drum, get off that slope and choose another route option without wind affected slab snow.

It still is early season: Early season dangers explained here (link to summary by Avalanche Canada).

Above 2,500ft Moderate

1,800 to 2,500ft Low

Below 1,800ft None

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

GENERAL DANGER RATING OUTLOOK

WEDNESDAY THURSDAY FRIDAY & SATURDAY
2-moderate

DANGER SCALE

PERSISTENT and WIND SLAB:

Elevation: 2500′ and above
Aspect: South aspects lee to NE wind and West gully walls where facets are buried by windslab
Terrain: Ridgelines, rollovers, crossloaded features
Sensitivity: Responsive
Distribution: Specific features
Likelihood (Human Triggered): Possible
Size: Small to Medium
Danger Trend: Steady until Friday’s snow significantly adds up
Forecaster Confidence: Fair
Details: North wind has loaded 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>

SNOWPACK DISCUSSION: Winds reached 74mph Tuesday out of the north at Thompson Pass, with an average of 50mph over 24 hours. This stripped and transported surface layers. Expect hardslab to 2 feet deep in gullies and lee of high ground laid in on old sugar snow.

While we haven’t quite reached avalanche threshold in the lower elevations, this incoming storm will change that.

20161123: Wind Slab on facets!!!! ECTP3 Q1 SC on 1mm NSF

20161123: 1F+ Wind Slab on facets!!!! ECTP3 Q1 SC on 1mm NSF

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

Over the last few days, some isolated pockets of windslab popped off near ridgetops to size 1.5, mostly steep south and west aspects in the alpine.

Recent Weather

WEATHER FORECAST for TODAY at 3,000 ft:
Temperature Forecast (Max *F): 7-17
Ridgetop Wind Forecast (mph):  E-SE/15-25
Snowfall Expected Next 24 Hrs(in): 3-4″
WIND & TEMPERATURE Past 24 Hours: Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction 20 / NE 57 / NE
Max Wind Gust (mph) / Direction 39 / ESE 74 / NE
Temperature Min / Max (*F) 19 / 26 4 / 10

Cloudy with snow flurries picking up, accumulating as much as a foot of snow by Friday. Temperatures warming as wind shifts to south/southeast onshore flow. Highs in the teens fahrenheit at Thompson Pass today, with 20s F Thursday. Southeast wind to 20mph with onset of snowfall.

Additional Info & Media

SNOW HISTORY: Valdez 11/30AM Thompson Pass 11/30 AM
Current Snow Depth 12″ 21″
24 Hour Snow / Water Equiv. o” /0″ 0″ / 0″
Storm Snow /Water Equiv. (11/26-29) 6” / 0.8” 12″ / 1″
November Snow / Water Equiv. 22.3″ / 4.1″ 49″ / 5.9″
Total Winter Snowfall / Water Equiv. 22.3″ / 4.1” 72″ / 8.3″
Snowload in Valdez 5.2 lbs/sq. ft.
SNOW DEPTH & WATER SURVEY (date) Depth Snow Water Equivalent
Milepost 2.5 Valdez  ?″  ?″
Milepost 18 ?″ ?″
Milepost 29 Worthington Flats ?″ ?″
Milepost 37 Tsaina River bridge ?″ ?″
This survey is done the first week of each month beginning in December.

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Thompson Pass RWIS weather station <here>
  • 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.avalancheforecasts.com/

Posted in VAC Forecasts.
Sarah Carter

Forecaster: Sarah Carter