Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Jan 27th, 2017–Jan 28th, 2017

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Mt Hood.

The avalanche danger Saturday will focus primarily on wet snow avalanches. Caution on steep solar aspects receiving direct sun during the warmest part of the day. Older wind slabs should be all but done, but isolated slabs may linger above treeline on specific terrain features.   

Detailed Forecast

Another mostly sunny day is expected Saturday with some high clouds at times. Warming should peak Saturday with freezing levels climbing to about 9000 feet by Saturday afternoon.

Winds should remain relatively light up to the Near Treeline Band and moderate Above Treeline. 

Watch for loose wet snow conditions on steep solar slopes as the temperatures climb under the direct or filtered sun, especially during the warmest part of the day, Saturday afternoon.  Moderate winds above treeline should help keep surface snow firmer,  limiting loose-wet activity on wind exposed slopes Saturday.

Older wind slabs have had the week to settle and strengthen and should now be confined to specific steep terrain features, mainly near ridges above treeline and will continue to stabilize Saturday. Continue to watch for recent wind effects below ridgelines and avoid steep slopes with obvious signs of recent wind loading.

 

Snowpack Discussion

Weather and Snowpack

An arctic air mass settled over the Northwest with fair, cold weather from the New Year through the second week of January. An atmospheric river moved over the Northwest 1/17-1/18 with heavy rain up to about 7000 feet on Mt. Hood during this stretch. Three day precipitation totals through Thursday 1/19 were about 1.5 - 2 inches of water at the NWAC Timberline and Meadows stations. 

From last Thursday 1/19 through Sunday, 1/22, generally 15-20 inches of snow accumulated at Mt Hood stations.

Fair weather with light winds and cool temperatures occurred Monday and Tuesday. A period of shifting and gusty winds Tuesday night helped redistribute recent snowfall to a variety of aspects by Wednesday morning. Light showers Tuesday night through Thursday produced about 1 to 4 inches of new snow. 

Recent Observations

On Monday, the pro-patrol at Meadows reported only pockets of stubborn wind slab above treeline on easterly aspects. This area had not been open or skied for 3 days and more closely represented true backcountry conditions.

NWAC pro-observer, Matt Schonwald was at Timberline on Monday and on the southeast slopes at about 6600 feet, finding right side up, increasingly resistant, settled snow with a good bond to the 1/17 crust. Shallow wind slabs showed little tendency to propagate via ski tests.

Meadows pro-patrol reported isolated areas of shallow and soft wind slab up to 12" deep on a variety of aspects above treeline due to shifting winds Tuesday night.  

On Thursday, 1/26 Laura Green found very good bonding of the 1 foot of progressively resistant storm snow to the very strong 1/17 rain crust, This observation was at about 6300 feet on a south aspect. 

Problems

Loose Wet

Loose Wet avalanches are the 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. 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.

Wind Slabs

Wind Slab avalanches are the 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.