Avalanche Forecast

Fair weather has returned to hurricane ridge, with cooling to slightly below freezing with diurnal warming to slightly above freezing. A melt-freeze cycle is likely to be seen with the surface snow conditions and some initial warming trend is starting to be seen during the day on Tuesday as a high pressure brings warmer air to the Olympics before the Cascades.Light rain was seen Saturday afternoon through Sunday morning along with mild temperatures caused wet surface snow conditions over the weekend. Significant snowpack settlement continues to occur in the Hurricane Ridge area with the recent warm and wet weather. On Friday, several natural wet loose avalanches were observed at all elevations.Large cornices developed during the last two weeks of January along ridgelines near and above treeline.The recent warm and wet weather has 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.

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.

The Hurricane Ridge area will see very significant warming, with snow levels rising to the top of the above treeline terrain on Wednesday. Mostly cloudy skies are expected with a slight chance of a light rain shower.Small to large loose wet avalanches are possible on all aspects and at all elevations on Tuesday as significant warming combine with the potential for sun breaks or light rain showers warm the snow. You are more likely to trigger a loose wet avalanche at lower elevations where wet snow conditions extend deeper in the snowpack. Loose wet avalanches may be small to large in size and may run farther and entrain more snow than you expect on Wednesday.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 warming on Wednesday 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 recently by NPS rangers. Glide avalanches occur in locations where wet smooth ground surfaces allow the entire snowpack to avalanche. Glide avalanches are highly unpredictable and as their releases generally are not tied to peak warming or rainfall. If you see glide cracks on a slope, avoid traveling on or below that terrain. While you are unlikely to trigger a glide avalanche, a glide avalanche would be large and deadly. With limited rain at Hurricane Ridge, the probability on Tuesday is quite low, but continue to travel around open cracks and rock faces with caution.

On Wednesday, the Pacific Northwest continues to sit between a robust and relatively stationary high pressure off the northern coast of California and a deep low over Hudson's Bay. The jetstream lies to our north, taking today's storm track and precipitation on a higher-latitude trajectory than previously expected. The resulting weather has been warmer than anticipated for Wednesday, with relatively drier weather. Winds have been and will continue to be moderate to strong on the east slopes of the Cascades at higher elevation and downslope winds to the east of the Cascades have scoured out the cold pool that normally resides there. Mazama saw an 18F jump in temperature in just one hour this morning due to a wind shift from E to W and temperatures are now in the mid-50's. Winds below crest-level have been light to moderate.To the west of the Cascade crest the atmosphere has been very stable on Wednesday morning, meaning that the temperature doesn't decrease significantly with height as you normally expect. Temperatures are in the low-to-mid 30's at most NWAC stations, including Camp Muir!Light precipitation is beginning to re-develop in the Northwest Cascades this afternoon with light amounts expected. Some locations in the central and north Cascades (west slopes) have also experienced freezing rain above 5000 feet or drizzle. As a system approaches from the W-NW tonight, W-SW winds will increase to the moderate-to-strong range by morning at crest level and snow levels will begin lowing slightly as the jetstream drops southward, pushing the ridge back south. In some cases east of the Cascade crest, winds will be very strong tonight.On Thurday, the reasonably strong, but relatively moisture-starved surface cold front associated with a short-wave trough will cross the Pacific Northwest, arriving in the Olympics in the early morning, then the NW Cascades around 10 AM and reaching Mt. Hood during the evening hours.Snow levels will drop significantly behind the front with rain changing back to snow at many mid-elevation locations between 1-4PM at the Mt. Baker base and between 4 and 7 PM for Stevens Pass and Crystal Base, with a changeover at Snoqualmie pass level likely after 7 PM. Most precipitation will be with moderate post-frontal showers behind the cold front and a potentially strong convergence zone that is likely to set up in the Stevens Pass vicinity during the afternoon and early evening hours.Some lighter convergence will focus lingering snowfall in the Snoqualmie Pass vicinity on Thursday night.

A moderate jet will remain over the area on Friday, with some light snow showers on a light W-NW flow along the west slopes of the Cascades.Late Friday into Friday night, an upper trough to the NE will retrograde to the west, spawning a back-door coldfront that pushes south and may bring a few snow showers to the Mt. Hood area on Friday night. Over Washington, expect clearing skies and light winds with low freezing levels.Saturday, should feature a brief period of relatively cool high pressure with clear skies, rebounding freezing levels, and light winds as a northward tongue of our trusty offshore high pressure slides east to replace the southward-moving shortwave trough. The high pressure should hold through Saturday night with clear skies and low freezing levels.Models agree that a storm will impact the northwest at some point on Saturday on a NW flow coming down the back-side of the high pressure ridge, but the models disagree regarding the track. Some models take the storm offshore into central Oregon, cutting off the potential for much moisture getting into our mountains. Other tracks take it directly into Washington during the daylight hours on Sunday. At this time, the upper and surface low look to bring another round of colder air and the potential for snow to lower elevations.