Avalanche Forecast
Issued: Mar 29th, 2018 11:00AM
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 make small Loose Wet avalanches possible at all elevations, especially on sun exposed slopes during the warmest part of the day. If you head to higher elevations, continue to avoid locations where you might expect lingering older Wind Slabs, mainly lee slopes near ridgelines.
Summary
Detailed Forecast
Another mild day Friday with sunshine will help make small Loose Wet avalanches possible on some steep slopes facing the sun, especially in the late morning and afternoon hours.
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 Friday. 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 no longer listed as an avalanche problem, in isolated terrain features there may still be lingering older Wind Slabs, such as 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
Several days of mild temperatures and sunshine, especially Thursday have allowed for a strong melt-freeze crust to form on all aspects up to at least 7000 ft.
The mild weather has allowed for older Wind Slabs to stabilize. Small Loose Wet avalanches were becoming possible over the past two days, but reports indicate these Loose Wet avalanches were very shallow and isolated to steeper slopes below rocks.
There are currently no significant layers of concern in the mid or lower snowpack.
Observations
On Thursday, professional reports from terrain in and adjacent to Mt Hood Meadows indicate only very shallow Loose-Wet avalanches were seen on specific steep slopes, mainly below rock outcrops. Older Wind Slabs were no longer considered a problem with a strong melt-freeze crust dominating the snow surface with shallow wet surface snow during the afternoon hours.
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 30th, 2018 11:00AM
