Avalanche Forecast
Issued: Mar 31st, 2018 12:09PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
NWAC,
Northwest Avalanche Center
Fresh and generally shallow Wind Slabs will likely develop near and above treeline Sunday afternoon, especially on NW-N-E-SE aspects. Use visual clues such as snow drifts, cornices, wind textured snow, and firm snow surface conditions that produce cracks to identify and avoid wind loaded areas. Avalanche conditions will deteriorate Sunday night.
Summary
Detailed Forecast
An incoming frontal system will spread clouds and eventually light precipitation into the Mt. Hood area on Sunday. Light rain and snow should develop mid-day.
Fresh and generally shallow Wind Slabs will likely develop near and above treeline Sunday afternoon, especially on NW-N-E-SE aspects. Fresh Wind Slabs may form quickly on the leeward side of terrain features and ridges near and above treeline. Use visual clues such as snow drifts, cornices, wind textured snow, and firm snow surface conditions that produce cracks to identify and avoid wind loaded areas.
Increasing cloud cover, rising W-SW winds and a slow cooling trend should limit new Loose Wet avalanche activity.
Avalanche conditions will deteriorate Sunday night.
Snowpack Discussion
Despite light winds and temperatures in the 30s to lower 40s near and below treeline Saturday, overcast skies for much of the day kept surface snow firm and limited new Wet Loose avalanche activity.
Several melt-freeze cycles occurred over the latter half of last week allowing older Wind Slabs to stabilize.
There are currently no significant layers of concern in the mid or lower snowpack.
Observations
On Saturday, Mt. Hood Meadows pro-patrol reported high overcast skies limiting the softening of surface snow on all aspects. No new avalanches were observed.
On Friday, professional reports indicated very little Wet Loose avalanche activity and that rock outcrops had already shed most of their snow.
On Thursday, professional reports from terrain in and adjacent to Mt Hood Meadows indicate only very shallow Wet Loose 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.
Problems
Wind Slabs
Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 1st, 2018 12:09PM
