Avalanche Forecast
Regions: Cascades - East.
Watch for signs of loose wet snow steep sun exposed slopes. Stay back from areas on ridges where cornices may be present and avoid slopes below cornices.
Detailed Forecast
Tuesday morning should start out mostly sunny but increasing clouds will be seen by Tuesday afternoon especially in the Olympics and northwest Cascades. Alpine winds will increase with high freezing levels and mild temperatures but with cooler east winds in the Cascade Passes. Significant rain or snow should hold off until Tuesday night and Wednesday.
Some initial sunshine and another day of mild temperatures Tuesday should make loose wet avalanches possible on steep slopes facing the sun. Be cautious on sun exposed slopes if the wet surface snow becomes deeper than a few inches.
Older wind slabs should have mostly settled and stabilized the past couple days. Significant new wind slab is not expected Tuesday as southeast to southwest winds won't transport sun affected snow. But continue to watch for signs of wind deposited snow on north facing terrain features.
Recent cornices have become quite large and continued mild temperatures Monday will maintain the danger of failing cornices.
Snowpack Discussion
Weather and Snowpack
The last strong storm cycle began Wednesday 2/8 and peaked on Thursday 2/9. This storm cycle deposited 2-2.5 inches of water equivalent in the northeast Cascades. The warming peaked Thursday afternoon with rain in the central east and southeast Cascades but precipitation remained snow throughout the event at all elevations in the northeast Cascades depositing 2-3 feet of snow at Washington Pass.
Westerly winds also became strong late Thursday into Friday building wind slabs and cornices.
High pressure Saturday to Monday brought increasing sunshine and warming temperatures. Temperatures reached the 40's and 50's in many areas of the Olympics and Cascades on Monday. This has brought snowpack settlement, some small loose wet avalanche activity and a decreasing avalanche danger.
The heavy storm cycle was a great snowpack test for any Persistent Weak Layers that we have not had good confirmation about. There was no evidence of any deeper releases as a result of the recent cycle and as such we will remove the Persistent Slab from the problem list.
Recent Observations
North
NWAC pro-observer Jeff Ward covered a significant amount of terrain in the Washington Pass zone Sunday. The few days of snowpack settlement, warming and sunshine have allowed for the 2-3 feet of recent storm snow to stabilize significantly by Sunday. Snowpack tests were negative Sunday and no triggered avalanches occurred. The avalanche problems were shifting away from storm related problems to warming and sunshine related dangers. A very large cornice failed naturally Sunday and cornices will be added to the problem list for the northeast zone.
A report via the NWAC Observations page indicates a shallow climax slab avalanche on a north slope on Mt Patterson near Winthrop on Sunday. There is likely to be shallow faceted snow in this low elevation area.
Jeff was out again in the Silver Star and Cedar Creek area with the NCHG on Monday and reported minor loose wet avalanches on solar slopes and no other activity or signs on instability. Snow was still cold on north slopes in the 5000-9000 foot range.
Central
A large avalanche off of Dirty Face Peak knocked in a garage door of a house on the north shore of Lake Wenatchee around 1130 am Thursday.Â
NWAC's Tom Curtis travelled in the Icicle Creek area near Cashmere Mountain Saturday. Tom did not get far as there was only a dusting of recent snow over a slick, firm crust. The greatest danger in this area was from uncontrolled falls on the slick crust as opposed to avalanches. Observations were not made in higher elevation terrain where wind slabs may have formed.
Another report via the NWAC Observations page for Dirty Face Peak for Sunday indicates that wind slab was unreactive there on Sunday.
Reports from the Mission Ridge pro-patrol mostly indicate a breakable surface crust from late last week and bad skiing on Sunday and Monday.
South
No recent observations.Â
Avalanche Problems
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1