Avalanche Forecast

This stretch of high pressure has featured mostly sunny and warm conditions with light winds for areas west of the Cascade crest and at higher elevations. Local colder, cloudier and breezier conditions have been seen in and around the Cascade Passes. More of the same can be expected on Thursday.

Loose wet avalanches are unlikely, but might be encountered in isolated steep solar exposed slopes below rocks or trees absorbing more radiation.  

This weather provides a nice opportunity to check out a variety of surface snow conditions but be sure to watch for early season/low snow travel hazards. Early season terrain hazards include poorly covered rocks, vegetation and creeks, particularly at lower elevations.

Heads up when a variety of weather conditions is likely on Friday. Snow may bury surface hoar or near-surface facets in some areas. Freezing rain may cap these layers mainly at low elevations in the passes or deep valleys. As you make your weekend plans, keep an eye on the weather forecasts.

Strong high pressure has now been over the region for over a full week. Sunshine and very mild temperatures have been the story with cooler temperatures and areas of low clouds at lower elevations and in the Cascade Passes. This weather has allowed for overall strengthening and consolidation of an already strong snowpack. Total snow consolidation along the west slopes of the Cascades ranges from 5-17" since December 3rd, with settled old storm snow of about 1.5 to 2.5 feet over the strong Thanksgiving rain crust. 

No human-triggered avalanches have been reported in over a week. Some natural small loose wet slides have occurred on mainly steep sun exposed slopes over the last week, but have become much less frequent over the past several days. Active wind loading has not been observed since late last week.

Surface conditions are highly variable. On solar aspects, surface melt-freeze crusts reform every night. On shaded and sheltered aspects, settled storm snow or near surface faceted snow are still providing some nice skiing and riding conditions. Many aspects in higher terrain now feature wind stiffened snow. Near surface faceting and surface hoar growth has been reported on colder, non-solar aspects throughout the Cascades but especially in the cooler Cascade Passes. These persistent grain types will become important when snowfall returns and watched as potential future weak layers. 

Observations

North

On Wednesday, NWAC Pro Observer Jeremy Allyn was on Green Mountain and found settled, stable snow conditions. At the summit, northeast slopes were wind affected, but there was no snow available for transport. At peak solar warming, spring-like conditions were found on steep solar aspects. There was little to no snow below 5000 feet. 

On Wednesday, the Mt. Baker professional patrol reported no glide or other avalanches. Surface snow softened in the sun. Snow on non-solar is staying cold and drier, but without near surface facets or surface hoar, likely due to being above the inversion.

On Monday, Pro patrol at Mt Baker Ski area reported two climax/glide avalanches off steep rock faces during the late morning hours. The slides were on an east and a south face, both were about 30 feet across and 3 feet deep, with debris piles 4-5 feet deep. No other avalanche activity was observed.

NWAC observer, Lee Lazzara travelled extensively Sunday, December 10th in the Swamp Creek / Winchester area from 3000-6100 feet. While the temperatures were quite warm and melting evident, surprisingly little current or previous loose wet avalanche activity was noted, mainly tree bombs. No avalanche activity was noted with variable but good ski quality in well settled storm snow, well bonded to the T-Day crust. Very little to no surface hoar or near surface facets were seen, other than in non-avalanche terrain near valley bottoms and creeks. 

Central

On Wednesday, NWAC Pro Observer Jeff Ward was on Jove Peak where he found little to no avalanche concerns. He found a mix of conditions, ranging from corn-snow on solar slopes, to powder on lower angle slopes at lower elevation, and large (1 cm+) surface hoar in the valleys. With the variable snow surfaces, he suggests it is going to be difficult to predict how the next storm snow is going to bond to these surfaces.

Professional Observer Dallas Glass skied non-solar slopes in the Alpental valley on Monday. He observed a very strong temperature inversion up to 4800' with cold, dry snow below the inversion. He found moderate easterly winds near treeline at 5200’. No snow was being transported. He found no avalanche problems that affected his travel. He noted the biggest travel hazard was low snow cover. Surface snow conditions were extremely variable.

South

Professional observer Ian Nicholson was in the Crystal backcountry on Wednesday. He found an overall consolidated, stable snowpack. He found limited good skiing on NE-facing slopes on a surface layer of settled powder, near-surface facets, and surface hoar. He noted an impressive volume of snow lost during this high pressure ridge. He noted that the easterly wind was picking up over the course of the day, but was not transporting snow.

A DOT crew was at Chinook Pass on Tuesday and reported noteworthy surface hoar up to 1 cm below the 4500' inversion.