Avalanche Forecast

The amount of new snow you find at Snoqualmie Pass will largely dependent on elevations. As of Saturday afternoon 4-6” of snow had accumulated at the top of Alpental with only a dusting at Pass level. Reports indicate that this new snow bonded well to the old wet snow surface. In some locations, this old wet snow has not refrozen yet.

The weather models continue to struggle with each round of precipitation. The latest information suggests that the bulk of the moisture will stay well south of Snoqualmie Pass and that the bulk of the warming will occur after the precipitation stops. At present, we’re even thinking the sun may make an appearance for part of the day. Will that be the case? You’ll have to pay attention to the weather and recognize if you are experiencing conditions that fall outside of the forecast. When you see observations that don’t line-up, seek lower angle and lower consequence terrain.

Even though the recent weather felt like winter, there are several springtime hazards in the mountains. Creeks, particularly at low elevations, opened wide during the recent warm weather. Many creek crossings are becoming difficult and potentially dangerous. Glide cracks continue to grow and a few glide avalanches have been found. Holes appeared near many trees and rock. Use caution when you travel near any of these spring hazards that could be hidden by a few inches of new snow.

Snow bridges over many creeks are beginning to sag, crack, and fail. Choose your creek crossings carefully. Photo: Dallas Glass

April 3rd, 2019

Spring snowmelt

The snowpack in much of the Cascades has changed dramatically in the past two weeks. The weather has shifted solidly to spring-like patterns. The spring warm-up started in mid-March with a prolonged period of relatively clear skies and warm temperatures. Moving into April, we’re seeing periods of unsettled spring weather bringing rain to many low and mid-elevation slopes and snow to upper elevations.

Very bare southeast aspects of Rock Mtn/Nason Ridge. April 2nd. Photo: Josh Hirshberg

Since the peak height of snow in mid to late February, mountain weather stations in the 4,000-5,000ft range show an average of 27% decrease in height of snow. Looking at weather stations in nearly every zone, the percentage decrease ranged from 22-29%. This year's spring snowmelt is much earlier than normal. Traveling in the mountains the loss of snow coverage is most noticeable on southerly, sun-exposed slopes and below 4,000ft. On northerly aspects and slopes above 5,500ft, the snowpack has seen less dramatic changes and has even maintained some dry layers.

NWAC climatological snow depth data from April 1st. You can view it on our website here.

Spring avalanche considerations

As you head into the mountains there are a few questions to ask yourself common to spring avalanche conditions:

1. Is there any recent snow accumulation that could cause avalanches? If so, what kind of avalanches could you trigger? And where?

2. What are the high and low temperatures of the past 24 hours as well as the forecasted temperatures during the time you’ll be in the mountains? Could these create weak, wet snow surfaces?

3. How is the cloud cover contributing to the melting or freezing of surface snow? Did clear skies allow for a sufficient overnight freeze? Will the sun be strong enough to weaken surface layers?

Glide avalanches and holes opening up in rocky terrain near Mount Herman. Photo: Andrew Kiefer

Other considerations

In addition to daily avalanche hazard, the early snowmelt is creating some other travel considerations. Some roads and lower elevation slopes may not have enough continuous snow coverage for travel on snow machines. Holes melted around rocks, trees, and creeks could create a fall hazard. When nighttime temperatures and cloud cover allow for surface freezes, bring appropriate equipment to mitigate slip and fall hazard on steep slopes.

We are approaching the end of our daily avalanche forecasting season. The mountain weather forecast will continue into the spring, and the weather station data is available year round. Keep checking the forecast for conditions updates on the end of season information.