Avalanche Forecast

An exiting warm front should be departing to the east Tuesday with only a chance of a few lingering showers early Tuesday.  However, freezing levels should remain high Tuesday helping to maintain wet surface snow conditions with a likelihood of triggered loose-wet avalanches near and below treeline.  Above tree-line expect weakening cornices along ridges and possible older wind slab on open lee slopes.  These conditions will warrant careful travel and terrain choices. 

Watch for wet surface snow conditions and given the deep recent storm snow, expect any wet-loose avalanches that start small to possibly entrain large amounts of snow.  Avoid terrain traps and steep slopes and watch for signs of natural wet loose activity.   

Cornices have grown large over the last 2 weeks. A cornice failure could provide a large enough load to trigger a destructive avalanche. With the warming Tuesday...expect cornices to become more sensitive and likely to fail.  

Continue your careful snow pack evaluation and cautious terrain selections during the work week.

Recent Northwest Weather

An extended mild and dry period occurred the latter half of January generally forming a crust in all areas. Very cold weather followed in early February which produced light low density snowfall, near surface faceting, and faceting near and just above the crust.

Frontal systems over the weekend were weaker than the frequent systems seen over the past 2 weeks.  Until we have an extended break in the storm cycle...the running tally for water equivalent over the past two weeks is about 8-10 inches with snowfall about 6 - 7 feet at the NWAC weather station at Hurricane Ridge and the Waterhole Snotel.

Observations for Hurricane Ridge area

Recent snow conditions have all but changed dramatically as of Monday in the near and below tree line zones as rain has returned.  Generally light rain has fallen through late Monday with Hurricane Ridge weather station reporting a high of 35 F at 5250 ft early Monday afternoon along with light rain.  This has quickly changed the recent low density dry snow to shallow wet snow conditions while likely causing some shallow loose-wet avalanches on some steeper unsupported terrain features, though there have not been confirmations of any avalanche activity as of Monday evening.  

Several avalanche cycles have occurred over the last 2 weeks. The last natural cycle likely occurred during the middle of last week when the road to Hurricane Ridge was closed. NPS employees found avalanche debris up to 8' deep just off the Hurricane Ridge road at 3600 ft while plowing Thursday. The start zone was likely in the near-treeline zone on a S-SE aspect. 

The late January crust layer and associated weak layers are now deeply buried by all the new storm snow, but still producing areas of collapsing and large whumpfing as reported in a NE meadow below treeline by a frequent TAY-er in the Hurricane Ridge area. The same skier had pictures of some very large cornice collapses.

On Sunday Feb 23, NWAC observer Katy Reid found relatively stable profile of right side up storm snow, meaning lower density surface snow accumulating on denser older snow layers with little avalanche activity through the day.  However some warming in the afternoon did cause some surface cohesion producing some shooting cracks from skies as shallow soft slabs formed.  On Friday stubborn but still possible to ski trigger wind slab were found on northerly aspects above treeline. She also observed quickly releasing wet loose avalanches on below treeline on solar aspects reacting to the strengthening February sunshine. With the addition of Monday's light rain these loose-wet slides should grow in number.  

   

Shallow soft slab cracking due to afternoon warming.  D2 loose-dry slide.  Sunday 2/23 Maggies, Hurricane Ridge by Katy Reid.

The mid and base pack at Hurricane should still consist of mostly stable crusts and melt form layers from periods of warm weather earlier this winter.