Avalanche Forecast

Light rain was seen Saturday afternoon through Sunday morning along with mild temperatures caused wet surface snow conditions over the weekend. Since this time, temperatures cooled to near freezing Monday, before a warming trend took hold Tuesday and Wednesday with temperatures reaching into the 40's Wednesday. Further snow melt has occurred, but not much more settlement.The recent warm and wet weather has allowed water to drain through the snowpack to produced glide cracks on slopes with smooth ground surfaces. Observations indicate glide cracks in common locations such as 20th of June, Steeple, and the Steep-and-Icy avalanche paths.Large cornices developed during the last two weeks of January along ridgelines near and above treeline.

NWAC pro-observer Matt Schonwald and NPS Rangers traveled in the Mt Angeles areas Friday. They observed moist to wet surface snow up to 6000 feet. Wet loose avalanches were seen releasing during sunny breaks around mid-day. They identified and avoided traveling near or below large cornices.

Cooler temperatures, mostly cloudy weather leading to partial afternoon sunshine, and windy conditions on Monday will limit wet snow problems on Monday.Wet snow will take some time to firm up and temperatures will remain mild or slightly above freezing most of the day on Thursday, so you still may be able to trigger a small loose wet avalanche in the terrain on Thursday. Check the depth of your boot or ski penetration. At all elevations, avoid steeper solar slopes where wet, slushy snow becomes deeper than a few inches.Large cornices exists primarily on NW-SE aspects along ridgelines in the Hurricane Ridge area. Recent mild air temperatures and rain have made these massive blocks of snow more likely to fail. After a several days of cooler weather, additional warm temperatures through Thursday morning will increase the likelihood of failure, so continue to give cornices a wide berth and avoid travel directly below corniced slopes. Several glide cracks have been reported by NPS rangers. At this point these cracks should be more of a terrain hazard than an avalanche problem.

Strong WNW flow near and above crest level persists across the Pacific Northwest Thursday afternoon. The region is being squeezed between an upper ridge offshore and a trough across western Canada, thus tightening the gradients over the forecast area.A  weak frontal boundary moved across the region early Thursday causing a period of mostly light precipitation at high freezing levels. Low level moisture is now being lifted along the west slopes in moderate onshore flow, maintaining light precipitation along the west slopes and over the volcanoes.Little moisture will make it much further south than about Mt Rainier Thursday afternoon and night.The greatest expected precipitation will be over the Stevens to Snoqualmie Pass area in an active convergence zone which should gradually weaken Thursday night. Freezing levels remain relatively high Thursday afternoon and should lower significantly in the wake of the passing disturbance Thursday evening and overnight.The ridge offshore gains strength Friday and turns the upper level flow to a more northerly direction. This should cause further cooling but more drying with only a few scattered showers expected Friday.

The region should be dominated by cool and dry northerly flow aloft on Saturday, being on the downwind side of the upper ridge offshore. This should provide a mostly fair and cool day Saturday.There remains a great deal of uncertainty in the computer weather models regarding an expected disturbance to impact the region Sunday. One strong case tracks the system from off Vancouver Island early Sunday southward, mostly offshore, providing only a glancing blow. Another solution is to move the disturbance across the region. Either way, it is not a strong system, but the details remain uncertain. Whatever precipitation received should fall with relatively low freezing levels.The ridge offshore should rebound Monday to bring a cool and drier NNE flow. Showers should end early Monday with gradual clearing.