Avalanche Forecast

A strong but quick moving front will bring a period of strong winds along with light precipitation Thursday night for the Mt. Hood area. Winds and showers should quickly taper down on Friday morning with a clearing trend expected along with cool temperatures. 

Shallow new wind slab should be the primary avalanche problem due to a period of moderate to strong westerly winds Thursday afternoon and/or Thursday night and may load leeward aspects mainly near and above treeline. 

Storm slabs are expected to be the most reactive and likely to trigger Thursday night during peak warming and storm intensity. However, sensitive storm slabs may linger and be found in wind sheltered terrain Friday. More snow is expected from Snoqualmie Pass and north to Mt. Baker with this storm and the avalanche danger will be rated higher to account for the additional expected snowfall.  

The 12/17 PWL persistent slab problem is becoming more deeply buried and less sensitive in snowpack tests but still warrants attention in the Cascades for areas without the Solstice crust layer. Recent and new loading may make this layer more sensitive to triggering where it is still present. Remember that persistent weak layers are generally involved in larger avalanches. Avoid steeper slopes in areas where you still find this layer reactive in snow pits. 

Weather and Snowpack

Strong storms around the Solstice deposited generally 3 inches of water equivalent recorded at NWAC stations on Mt Hood. Unfortunately, much of the heavy precipitation fell in liquid form with rain reaching above 7000 feet.

A strong front and strong west flow aloft was seen over the Cascades on Monday and Tuesday. NWAC stations at Mt Hood had strong west winds and the station at Mt Hood Meadows had about 2.5 feet of new snow for the 48 hours ending Wednesday morning.

A warm front draped over the north Washington Cascades Thursday left Mt. Hood in the warm sector with temperatures pushing above freezing at most stations under mostly sunny skies. 

Recent Observations

Reports from the Mt Hood Meadows pro-patrol following the Solstice indicated a significantly different snowpack following rain, avalanches and cooling. A stout surface crust was found on all elevations up to at least 7200 feet. On exposed terrain, the crust was very supportable while in treed terrain the crust ranged from breakable to supportable.

The pro-patrol at Mt Hood Meadows Tuesday reported very sensitive storm slab releases, with slabs releasing upon approach to ridges or steeper features.

The pro-patrol on Wednesday reported below treeline widespread sensitive 6-12 inch storm slab releasing by ski tests. Near tree line wind slab became reactive to 1-1.5 feet with good propagation. Above treeline explosives were used with larger hard deep wind slab releases where ski tests where considered too dangerous. One very large hard slab released with explosives was R4 - D3.5 with an average crown depth of 4-6 feet with a maximum of 8 feet down to the Solstice crust. Again this was released with explosives and not repeated during control work Wednesday but impressive!  Wind slab near and above treeline was seen mainly on E-SE slopes.