Avalanche Forecast
Issued: Mar 28th, 2018 1:27PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet.
NWAC,
Northwest Avalanche Center
A strong March sun will sunny slopes creating heightened avalanche conditions during the middle of the day as the surface crust breaks down on Thursday. Small Loose Wet avalanches are possible at all elevations, especially if the sun pops out for an extended period of time. If you head to high elevations, navigate around locations where you expect winds may have deposited snow near ridgelines.
Summary
Detailed Forecast
Heightened avalanche conditions will exist on specific slopes on Wednesday, particularly between 10 AM and 3 PM.
Small Loose Wet avalanches are possible on steep sunny slopes near and below treeline, with the sun likely to be out for an extended period of time on Thursday. Watch for warning signs like new roller balls, pinwheels, and natural Loose Wet avalanches that indicate increasing hazard. Even small Loose Wet avalanches may carry you into terrain with high consequences such as over cliffs or into gullies.
Although it is becoming unlikely, in isolated terrain features you can still trigger a Wind Slab avalanche at upper elevations on steep slopes near ridge-tops or in cross-loaded terrain features. Watch for clues like variable snow height, drifts, cornices, and stiff snow that produces cracking. These are all indicators that you could trigger a Wind Slab. You can avoid triggering these avalanches by steering around steep roll-overs, unsupported features, and obvious start zones where you suspect Wind Slabs.
Snowpack Discussion
On Wednesday, temperatures in all elevation bands reached close to 40 degrees or higher under filtered sunshine. Winds decreased from moderate and were becoming light out of the WNW. The warm temperatures are helping wind slabs settle rapidly and there has been no recent slab avalanche activity. Small loose wet avalanches were becoming possible on Wednesday afternoon as temperatures warmed.
Moderate West winds were seen near and above treeline Monday and Tuesday and a small amount of precipitation created a rain or freezing rain crust up to 7000 feet. Warm temperatures limited wind transport of the 12-14" of accumulation from Friday through Saturday.
There are currently no significant layers of concern in the mid or lower snowpack.
Observations
On Wednesday, Mt. Hood Meadows pro-patrol reported crusts extending to 7000 ft in the terrain with Loose Wet conditions developing around mid-day as the crust broke down. Patrol had good visibility onto higher elevation terrain and saw no signs of recent Wind Slab avalanche activity.
On Tuesday, Mt. Hood Meadows pro-patrol reported moderate west winds near and above treeline but limited snow available to form new wind slabs in their area. Warm temperatures and occasional light rain caused small Loose Wet avalanches on all aspects near and below treeline, but especially on southerly aspects.
Problems
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 29th, 2018 1:27PM
