Saturday-Tuesday

Issued: Sat, Nov 19, 2016 at 8AM

Expires: Tue, Nov 22, 2016

Be mindful of the early season conditions. The snowpack is quite variable in relation to elevation and the pass proper. In general, expect less powder and more crusts on the south side of the pass and deeper/softer snow the higher and more interior you travel due to colder temperatures (less rain) during the recent storms.

Be careful near ridges, rollovers and crossloaded gullies: sensitive windslabs have been human triggered recently and moderate winds will continue to create new, touchy ones. See activity section below.

Read this summary on early season conditions posted on 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

Wind Slab Problems:
While recent offshore winds have backed down, previous gusty and variable winds had dominated the pass during and after last weekend’s big storm. This reversal of wind direction funneling through the pass has created wind slabs on many aspects, but the most sensitive ones are likely lee to the more recent outflow wind. Snowmachiners found and triggered this problem last Wednesday. Mostly southerly facing slopes are building this new problem, but make sure other aspects aren’t susceptible by checking the winds and how they are moving and loading snow on the terrain you are immediately using. The cold temps out there will necessitate more time for freshly transported snow to bond to old surfaces.

Snowpack:
Despite last night’s dusting that seemed to favor town with about an inch of snow, the most recent significant storm ended Nov.12. It deposited 2.5 inches of water equivalent in our mountains, and above 3500′, it all came as snow. It likely accumulated to 3 feet in the upper elevations.

A few eager snowmachiners were exploring around the flats and wind-loaded faces Wednesday, but seemed to often be punching through to vegetation. Creeks are wide open and alders not buried.

Explorations last Wednesday revealed about 2 feet of mostly soft snow (few thin crusts) at the highway below Nicks and only a foot at on the ground at the hairpin below Moonlight. The south side of the pass saw significantly warmer weather and rain, so therefore only has 4 inches of soft snow at the surface before one encounters a significant crust. See more observations below.

Earlier last week on the north side of Thompson Pass, a cloud ceiling at the pass height developed a widespread rime layer at the surface. In contrast, the snow surface on the cloud-free, south side of the pass was dominated by surface hoar up to 12mm in height. While this crystal can be gorgeous, it also can become a future problem worth noting and monitoring….help us do that by submitting what you find in the coming days!!! These guys can linger in cold, clear and calm areas at all elevations.

Please share your observations so everyone can be in tune with the conditions and make wise decisions – even just a photo or quick summary of whats going on out there helps all of us.

Pictures:

20161116: 27 Mile Conditions

20161116: 27 Mile Conditions

20161116: N Side Cloud Ceiling

20161116: N Side Cloud Ceiling & Open Creek

Recent Avalanche Activity

Wed. Nov. 16: A snow machine triggered a D1.5 soft wind slab on the southerly aspect of DOT/Loveland Ridge just above camp. The photo doesn’t help much other than with general location. Crown (just at sun/shade line) was likely 2ft thick and peeled off a fairly steep, wind loaded slope.

20161116 DOT conditions with machine triggered D1.5 on ridge to right of shed.

20161116 DOT conditions with machine triggered D1.5 on ridge to right of shed.

 

Recent Weather

While a weak front graced us with an inch of new snow in town last night, it didn’t seem to do much for the pass. Look for breaking skies scattered with a few flakes today until another front hits us late tonight. 2-3 inches could accumulate by late Sunday. Temperatures will warm as the front passes through, but should remain below freezing in town. As more lows track through the gulf this coming week, cloudy skies with a hint of snow could greet us Monday and Tuesday.

Additional Info & Media

SNOW HISTORY: Valdez 11/19 AM Thompson Pass 11/19  AM
Current Snow Depth 2″ 21″
24 Hour Snow / Water Equiv. 1” /0.1″ 0″ / 0″
Storm Snow /Water Equiv. (11/11-12) 2” / 2.1” 17″ / 3″
November Snow / Water Equiv. 3″ / 2.85″ 35″ / 4.7″
Total Winter Snowfall / Water Equiv. ?″ / ?” 58″ / 7.1″
Snowload in Valdez 0
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.

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>.
  • Thompson Pass weather <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>

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.

Forecaster: Kevin Salys