Avalanche Forecast

A weak front will move across the Northwest Cascades late Thursday. This should cause southwest winds and a cooling trend. Snowfall should be pretty light except with 5-10 inches looking likely in the Mt Baker area. By Friday a large digging trough offshore should cause much lighter winds and but with renewed snow mainly over the south Cascades with low snow levels.

Wind slab should be the primary problem Friday. Southwest winds in the last storm cycle and for the late Thursday system make this most likely on north to southeast slopes. Watch for firmer wind transported snow mainly north to southeast slopes.

The latest tests of the December 17th PWL in the Cascades don't seem to indicate a regionally reactive layer. There is a lot of uncertainty regarding this layer and there still may be a lot of variability from area to area and location to location. Snow pits valid for slopes you intent to ski or ride may give some indication of the presence and reactivity of this layer. But skiing or riding on lower angle slopes is the safest bet until there is more certainty that this layer is no longer a problem. While triggering this layer seems unlikely  remember that PWL's generally cause larger avalanches.

Mostly light new snow amounts and the cooling trends in the Olympics and Washington Cascades make a significant new storm slab problem seem unlikely on Friday.

The surface crust formed in some areas following the storms early this week is reported to be strong and hard enough in some areas of the west slopes to present an out of control fall danger. Avoid steep hard slopes where there will be fall consequences if you are not confident you can manage this problem by walking or using ski or boot crampons.

Weather and Snowpack

Clear and cold weather from Wednesday, December 14th to Friday, December 17th allowed widespread surface hoar and near surface faceted snow to develop in the Olympics and Cascades. Thin sun crusts formed on steeper solar slopes during sunny periods. In many areas, these persistent grain types were buried intact by December 18th during a period of light snow and light winds.

Strong westerly flow directed two Pacific frontal systems across the Northwest Sunday night and again Monday night with generally up to an inch of water accumulating at the Hurricane Ridge station through early Tuesday morning. Storm snow totals varied quite a bit due to a mix of precipitation types during the storm cycle. Many areas in the Cascades experienced a natural avalanche cycle involving either shallow, loose wet or storm slabs Monday night or early Tuesday morning.  A strengthening rain crust was noted in many areas by later in the day Tuesday with the arrival of colder air.  

Westerly winds were especially strong with the 2nd system late Monday night and into Tuesday with gusty winds mixing down into usually more wind sheltered terrain.

Cool, dry weather with sunshine Wednesday helped settle recent storm snow and possibly create a thin sun crust on steep directly south facing slopes.  

Recent Observations

The road to Hurricane Ridge is closed midweek and no observations have been received since last weekend.