Avalanche Forecast

Light rain and snow should develop for the north Cascades in the afternoon while only a general increase in afternoon clouds should be seen for the central and south Washington Cascades. Mild freezing levels will continue Monday with temperature inversions in the Passes and sheltered valleys. Alpine winds out of the SW are forecast to ramp up Monday afternoon.  

Little change in the avalanche danger is expected Monday with recent wind slabs primarily found on N-W-S aspects. However increasing SW winds in the above treeline band may start to form shallow wind slabs on more easterly aspects. Remember that firmer wind transported snow is always your best sign of wind slab layers.

Small loose wet avalanches will be possible on steeper solar aspects Monday for areas in the south and central Cascades that see sunshine. However, loose wet avalanches will only be listed in the north Cascade zone where light rain below 4000 feet is expected in the afternoon. 

Avalanche watch issued Monday night through Tuesday: A drastic change in the weather pattern to wetter and milder weather should substantially increase the avalanche danger either Monday night or Tuesday.  

Heavy precipitation with a warming trend Monday night will most likely impact the north Cascades including the Mt. Baker area. A natural avalanche cycle should occur Monday night.

From Stevens Pass and southward to White Pass, precipitation amounts, type and timing are less certain and High avalanche danger may occur Tuesday or not until Tuesday night.  

An abundance of weak and cold snow in the upper snowpack combined with the potential for rapid warming and high precipitation rates would lead to very dangerous avalanche conditions during this period and backcountry travel is not recommended. Check the forecast Monday evening for updates. 

Weather and Snowpack

A pair of warm fronts moved across the Northwest last weekend causing see-sawing temperatures to near or above freezing for areas away from the Passes with milder Pacific air finally dislodging colder air in the Passes late Sunday night 1/8. This allowed a rain or melt freeze crust to form in some areas below treeline before 5-15 inches of snow accumulated through Monday 1/9.  

A weak low pressure system, tracking across Oregon Tuesday morning through Wednesday afternoon, deposited another 3-6 inches of snow with light winds from Stevens Pass and southward, with Paradise adding another 12 inches. A period of strong E to NE winds increased Tuesday afternoon through early Wednesday before diminishing Wednesday afternoon.

An upper ridge over the northeast Pacific Ocean has caused fair weather Thursday through Sunday over the Olympics and Cascades with mostly light winds and moderating temperatures west of the crest and at higher elevations. Paradise reached into the 40s on Saturday and Sunday while strong temperature inversions and breezy cold east winds were seen in the Passes.  

Surface hoar and near surface faceting has been noted widely throughout the range in sun and wind sheltered locations below treeline. Sun crusts have formed on steeper solar aspects over the last few days. The best riding and skiing conditions have generally been reported in less wind and sun affected areas below treeline during this stretch of fair weather.

Recent Observations

NWAC pro-observers Dallas and Ian Nicholson were in the Crystal backcountry Wednesday to assess the distribution and sensitivity of fresh wind slabs from recent strong E-NE winds. They found that wind slabs were becoming larger as they moved into the near tree line band and exposed ridges. NE-E-SE facing slopes were stripped of recent snow with new reactive wind slabs on N-W-S facing terrain and cross loaded features. In wind sheltered terrain below treeline, the storm snow was right side up and lacked slab structure with excellent skiing conditions.

Some reports are available via the NWAC Observations page for Wednesday and Thursday. in summary skiers triggered wind slab layers on Mt Herman near Mt Baker and in the Slot Couloir on Mt Snoqualmie on Wednesday. Potential wind slab layers were noted at Stevens and at Snoqualmie on Thursday but no avalanches were triggered.

NWAC pro-observer Jeremy Allyn was out in the Alpental Valley on Friday and mainly found that recently formed wind slab in the near and above treeline was settling and strengthening.

Lee Lazarra was taking observations for NWAC in Glacier Creek, NW of Mt. Baker proper on Saturday. Lee found generally good riding conditions in the trees on non-solar aspects. Solar aspects were softening and likely to form sun crusts overnight. Snow surfaces just below and along ridges were variable from last week's winds and Lee found recent wind slab to be unlikely to trigger in his specific area. Widespread surface hoar growth was noted in usual spots like creek beds, but surface hoar size diminished higher in the below treeline band.