Avalanche Forecast
Regions: Snoqualmie Pass.
The Bottom Line: Gradual warming and light winds should produce surface snow melt on steep sun exposed slopes during the warmest part of the day. Continue to watch for local wet-loose slides on steep solar aspects.
Detailed Forecast
Temperatures should warm Monday as freezing levels climb under high pressure back up by 4 to 8 degrees from Sunday.  Plenty of sunshine, warming temperatures and light winds Monday should allow for gradual surface snow melt on steeper solar aspects during the late morning and afternoon, especially mid and higher elevations.
Be aware of quickly softening surface snow in the late morning through afternoon hours on solar aspects. Natural pin-wheels or sinking in more than ankle deep means it is time to get off that slope and out of the way of steeper southerly slopes and avoid terrain traps.Â
Continue to approach wind loaded slopes with caution, isolated wind slab may linger on N thru SE aspects near and above treeline zones.  Â
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Snowpack Discussion
The most recent storm cycle to impact the PNW ended Tuesday after lasting for nearly a week depositing 2 - 4 feet (60 - 120 cm) of snow for most west slope Cascade sites and Hurricane Ridge in the Olympics. Strong westerly wind accompanied the much of the storm cycle from Friday through Monday and transported new snow onto lee slopes near ridges, building wind slab. The tail end of the storm cycle from a week ago Sunday afternoon through early Tuesday was accompanied by a warming trend that brought rain to mid elevations and deposited a heavy dense snow layer at higher elevations. The main avalanche activity with this cycle occurred a week ago Sunday, Jan 12th with large to very large D2 to D3 natural avalanches reported throughout the west slopes with start zones mainly in the near and above tree-line zones on wind loaded aspects. Natural avalanches released within the storm snow with isolated but larger slides up to 5' were produced by local ski patrols with explosives down to older crusts.Â
Tuesday through Saturday has seen a return to very mild temperatures and sunshine. The warmer and drier weather has allowed for snowpack settlement of about 7-14+ inches over the past week. Last weeks storm snow is now generally well-bonded.  At higher terrain snow surfaces vary from dense powder on wind and sun sheltered aspects...to chalky wind board on lee slopes...to sun crusts or soft shallow wet snow on solar aspects, depending on time of day.  Due to the low winter sun angle the somewhat supportable rain crust at low and mid elevations on non-solar aspects remains firm during the day.  On a better note, there have been many nice reports of good spring-like corn snow on sun exposed terrain at higher elevations over the past several days.
About 5-10 degrees of cooling Sunday Jan 19 helped limit surface snow melt and maintain firmer surface snow and hence a lower danger of wet-loose slides on solar aspects.Â
Recent observations:
Near surface facets on shaded slope near Hurricane Ridge Olympics 1/18/2014, Katy and Tyler Reid
Recent natural wet-loose activity on solar aspects above Hurricane Ridge, 1/18/2014, Katy Reid
Wind and sun effects near Panorama Pt above Paradise Mt Rainier, Dennis D'Amico
NWAC observer Tom Curtis on Wednesday from Jove Peak reported a sudden collapse and a clean shear in a compression test on an east aspect near-treeline.  However, this layer did not propagate in an Extended Column Test but suggests there may still be some lingering but increasingly isolated wind slab on lee slopes, though four days of mild weather may have now settled this layer.Â
Photo by NWAC observer Tom Curtis on Jove Peak at 5400 ft
The warm and sunny weather activated solar aspects with large wet-loose avalanches reported Tuesday and Wednesday that ran into the below tree-line zone in the Stevens Pass area. Â
Photo from the Smithbrook area near Stevens on Tuesday by NWAC observer Dallas Glass and a short video of the wet loose slides:  https://www.youtube.com/channel/UCXKN3Cu9rnnkukkiUUgjzFQ
For the Olympics and west slopes of the Cascades a generally favorable mid and lower snowpack exists and is expected to consist of crust layers and melt form crystals. The avalanche danger is locally lower in the Olympics where the snowpack on windward and solar aspects near and below tree-line has less snow and ample terrain anchors. Â
Local non-avalanche hazard Snoqualmie Pass area:  On Monday a heavy local freezing rain event occurred in the Snoqualmie Pass area above about 4500 feet, reported to the top of Alpental above 5500 feet covering the surface with about a 2 inch clear ice crust.  This crust should break down over time but a fall on this surface would result in a long and dangerous ride!     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: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1
Wind Slabs
Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: North, North East, East, South East.
Elevations: Alpine.
Likelihood: Unlikely
Expected Size: 1 - 1