Avalanche Forecast Stevens Pass

Date Issued: Valid Until:

Josh Hirshberg,

Avalanche Forecast

Sun Jan. 27th ยท 6:00PM

Alpine

Danger Ratings Low

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low

Problems

Persistent Slabs Persistent Slabs

Alpine

Danger Ratings Low

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low
The Bottom Line: Expect more warm temperatures and sun. If you are heading to upper elevations or less traveled terrain, take time to assess the snow. Avalanches may be possible in isolated or extreme terrain.

Snow and Avalanche Discussion

Warming of the snow surface has a few concerns on our minds. You could trigger isolated loose wet avalanches on sunny slopes with extreme, rocky terrain or areas of shallow snow. If you sink to the top of your boots in wet snow, it's time to move to more supportive, cooler snow. Additionally, cornices commonly fall with prolonged warming. Limit your exposure and avoiding traveling on or below these features.

Monday will be another day of warm temperatures and sun. You may still find soft, wet snow on steep sunny slopes. Most loose wet avalanches you will see are at least a few days old or from a rain event on the 23rd. A number of factors will help keep snow surfaces slightly more frozen on Monday. Air temperatures should drop a bit and an easterly wind will cool the surface snow.

Check out the Regional Synopsis tab for details on the last weeks storm and avalanche activity.

Loose wet avalanches ran on January 23rd with rain. Lichtenberg Mtn, SW. Photo: Josh Hirshberg

Weather Forecast

Mon 28th Jan 13:28 - Kenny Kramer

Weather Synopsis for Monday night through Wednesday

A ridge of high pressure will remain centered offshore on Monday night and weak gradually through Wednesday, maintaining fair and dry weather. Surface high pressure has strengthened east of the Cascades Monday causing increasing easterly winds across the Cascade crest and through Stevens, Snoqualmie and White pass.  Surface high pressure and cooling easterly winds have strengthened a temperature inversion with below-freezing temperatures returning to the passes and lower elevation areas, especially along the east slopes.

Some high clouds will continue to spill over the ridge at times through Wednesday, however, plenty of sunshine will persist both Tuesday and again Wednesday.

The current weather pattern typically causes extensive low clouds and fog along the east slopes and valleys, however, a lack of sufficient low-level moisture is limiting clouds and fog to just patchy areas.

The moderate easterly winds Monday should gradually subside Tuesday through Wednesday, allowing for warmer temperatures.

The next approaching weather system expected to undercut the offshore ridge has been consistently forecast to move southward well offshore Tuesday and head towards southern California Wednesday, missing the region entirely. 

Weather Forecast

Sat 26th Jan 14:48 - Robert Hahn

Weather Synopsis for Saturday night through Monday

A high-amplitude late-January ridge centered over our region on Sunday continues to dominate the weather pattern through early next week. The ridge is bringing some of the warmest temperatures our higher elevation stations have seen in several months, while lower elevation stations have managed to warm up as well in spite of the overall inversion (a pattern where colder air sinks and pools in valleys). Overnight, the inversion should gain some strength as clear skies and light winds continue, with patchy very low-level fog developing once again. The fog should reduce in extent during the daytime. 

A shortwave weather system riding over the ridge Saturday night and moving down the Rockies into Montana on Sunday, resulting in the ridge axis moving slightly offshore where it will remain into early next week. This is likely to drop freezing levels by 2000 ft relative to Saturday. The upper-level flow should shift northerly while a colder high pressure from interior British Columbia drops southward along with it late Sunday, bringing cold air to the North Cascades and areas east of the Cascade Crest. It will also drive an offshore pressure gradient. Winds will pick up Sunday night and Monday.

Problems

Persistent Slabs

Persistent Slabs

While they are very difficult to trigger, persistent slab avalanches can be dangerous. With the warm temperatures and recent load, there's uncertainty about these avalanches at upper elevations. The best approach is to pick smaller pieces of terrain, and minimize exposure to large avalanche paths until we can be confident that these avalanches are no longer a concern. 

A layer of surface hoar, buried on January 17th, should be 2 to 3 feet down from the surface. The main concern for the weak layer is above 5500ft. Digging in the snow and using snowpack tests can help you confirm if it exists. Try not to make decisions on a single test or snow profile.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 2