Avalanche Forecast

Mainly high clouds are expected Friday with light winds and a continued warming trend.   

Watch for loose wet snow conditions on steep solar slopes during sun breaks or thin high clouds, especially during the warmest part of the day, Friday afternoon. 

With recent observations showing wind slabs bonding and stabilizing, we will remove them from the avalanche problem list. However, any lingering older wind slabs are most likely on SW-NW-NE aspects due to strong S-E transport winds last weekend. Watch for recent wind effects near and below ridgelines and avoid steep slopes with obvious signs of recent wind loading. 

More information is needed about several potential persistent slab threats, particularly in the northeast and central-east zones. Due to the lack of direct avalanche activity on any PWL, the avalanche danger will be maintained at Moderate. Please take the travel advice to heart, evaluating snow and terrain your traveling through carefully, erring on the side of caution if you are unsure about the snowpack structure in your area and realizing large avalanches are possible in isolated areas under Moderate danger.  

Weather and Snowpack

An arctic air mass settled over the Northwest with fair, cold weather from the New Year through the second week of January. Surface hoar and near surface faceted crystals formed in wind and sun-sheltered areas during this period. Observations are beginning to paint a picture that these weak persistent grain types were buried intact in portions of the central-east and northeast zones. 

An atmospheric river moved over the Northwest 1/17-1/18 causing heavy snow in the northeast zone with about 2 feet of snow accumulating at Washington Pass. A mix of snow, sleet and freezing rain was likely seen in the central-east zone and also in some lower elevation areas east of the crest. Lyman Lake Snotel, Holden Village and Berne Camp east of Stevens saw about a foot or more of new snow while Mission Ridge and Lake Wentachee saw about 6 inches. Rain was likely seen up to about 5-6000 feet in the southeast zone during this stretch.   

With the arctic air mass finally displaced and cool easterly flow abating Thursday 1/19, many lower elevation sites east of the crest warmed to near freezing. Showers Saturday and Sunday deposited about 2-5 inches of new snow with local strong S-SE winds observed during this period. 

Fair weather with light winds and cool temperatures have been seen since Monday this week with temperatures beginning to warm Thursday.

Recent Observations

North- 

NWAC pro-observer Jeff Ward was in the Hairpin Valley of Washington Pass Saturday 1/21 and in specific terrain found reactive tests (PST) on buried surface hoar just under the thin 1/17 crust, buried 65 cm (2 feet) in that area. It is unsure how widespread the buried surface layer is in this zone, so proceed with caution, especially lower elevation and near valley bottom slopes. Jeff provided this video.

The NCMG were out on Delancey Ridge and Vasiliki Ridge on Sunday 1/22 and reported wind transport at 6000 feet. Numerous ski tests gave no results on Delancey. A storm shear was seen at about 25 cm and no results were seen at a 1/17 interface. On Vasiliki ski tests gave very local results on the 1/17 interface. The NCMG were out again on Monday on Delancey Ridge and saw no avalanche results while skiing. Compression tests on a SE slope at 6000 feet indicated a hard resistant planar shear at 45 cm below the 1/17 interface so some of the surface hoar or faceted snow from the 2nd week of January may still be present.

Initial reports from the NCH Barron Yurt Wednesday indicate no direct signs of instability, but did indicate unstable results in snowpack tests, presumably around the buried surface hoar layer just under the 1/17 interface. Persistent slab will be listed in all of the east slope zones to deal with this uncertainty. 

In areas further east, away from the crest where a shallower overall snowpack exists, the recent storm snow in many areas has settled into a cohesive slab and overlies very weak basal facets formed during the very cold weather of early January. 

On Thursday 1/26, Jeff Ward reports very good stability while ski testing extensive terrain in the Washington Pass area. Older wind slabs had bonded and stabilized and no triggered avalanches occurred. Small loose-wet avalanches were seen on some very steep solar aspects. 

Central-

On Thursday, 1/19 the Mission Ridge pro-patrol produced 8-10 foot hard slab avalanches with hand charges that released down to the basal facets formed earlier this winter. These very large avalanches were on very specific wind loaded NE slopes just below ridgelines.

NWAC observer Tom Curtis was in the Blewett Pass/Diamond Head area Saturday 1/21 to assess post storm conditions. The major finding relates to the well documented 10-15 cm of basal facets in that region. Extensive observations in this region determined that significant rounding has occurred with these grains and no facets above the ground remain. The rounding of the basal facets may be limited to this specific terrain, so tests in other areas are encouraged, especially when travelling in terrain of consequence.

In Icicle Creek at 4500 ft on Saturday 1/21, a Stevens pro-patroller reported 20 cm of storm snow over buried surface hoar/faceted snow producing collapsing and shooting cracks. This corresponds with local Methow reports of instability related to a similar snowpack structure roughly between 4-5000 feet in areas further east of the crest with a shallower snowpack.

Tom Curtis was at Dirty Face above Lake Wenatchee Thursday, 1/26 and found a persistent weak layer of buried surface hoar, consistently buried about 2 feet (60cm). Test results were inconsistent upon multiple tests, some showing it to be reactive and others not. No avalanches were seen on this layer. 

South-

No recent observations.