Avalanche Forecast

A weakening front should move over the Northwest Tuesday afternoon and night. This may cause some mostly light amounts of snow along the west slopes but probably not as much as earlier expected.

The bigger story is the incoming atmospheric river on Wednesday. A warm front should south to north over the Olympics and Cascades Wednesday morning to afternoon. This should bring stormy wet weather with rising snow levels initially to Mt Hood Wednesday morning and to the Olympics and Washington Cascades Wednesday afternoon. East winds should do little to lower the snow levels in the Cascade passes.

Little change may be seen by Wednesday morning along most of the Cascade west slopes. But by Wednesday afternoon watch for increasing alpine winds and increasing moderate to heavy rain or snow and rising snow levels.

Mainly in the above treeline new wind slab of increasing density due to warming is very likely to form on lee slopes. Watch for firmer wind transported snow as the storm develops Wednesday afternoon.

Also mainly in the above treeline new storm slab of increasing density is also very likely due to warming. Watch for snowfall that begins to accumulate Wednesday afternoon at more than an inch an hour.

Rain in the below and possibly in the near tree line starting Wednesday afternoon is also likely to create loose wet avalanche conditions. Watch for pinwheels and natural loose wet avalanches.

The rain where  heavy enough by Wednesday afternoon may activate previous layers and cause releases of previous wind slab layers or wet slab avalanches mainly in the near and below treeline.

Weather and Snowpack

Last week was wet and relatively mild with a series of active fronts transiting the region resulting in fluctuating freezing levels and periods of very strong winds. The heaviest snowfall and precipitation occurred late Sunday 2/28 and Tuesday 3/1. The latter half of the week featured more rain than snow at NWAC sites along the west slopes.

Mid and lower elevations late last week and over the weekend saw natural and triggered loose-wet avalanches most days due to increasing solar effects or during rain events.

A front Sunday and a cooler upper trough Monday brought some snow with 2 day storm totals of about 2-12 inches along the west slopes ending Tuesday morning.

The mid and lower snow pack along the west slopes should generally be a stable mix of crusts and layers of moist and rounded snow crystals.

Recent Observations

NWAC pro-observer Tom Curtis was at Stevens Pass on Friday found evidence of lots of large loose wet and some wet slab avalanches.

Locally heavy rain at the Mt. Baker area led to sensitive loose wet ski cuts by the Mt. Baker pro-patrol Saturday morning. A natural loose wet cycle was observed in the Bagley Lakes area and one glide avalanche in unsupported terrain released nearby. Also in the Baker area, a glide avalanche occurred Saturday night off Shuskan Arm entraining moist surface snow and becoming very large while running to the valley bottom.

A report on Turns All Year for the Crystal area for Saturday indicated wet snow conditions with pinwheels on north and south slopes.

A report via the NWAC Observations page for Sunday for Snoqualmie Pass indicated wet heavy snow conditions and previous loose wet avalanches.

The pro-patrol at Alpental on Tuesday found 2 day storm snow of 8-12 inches on  the upper mountain but had no results by ski cuts and reported that sun breaks were not enough to cause loose wet snow. Explosive control caused areas of shallow 4 inch storm slab releases.