Avalanche Forecast

A moderate front should cause increasing winds and spread increasing snow especially to the above treeline of the east slopes Sunday afternoon with a slight warming trend.

This weather should build new wind slabs on lee slopes mainly near and above treeline by the end of the day. Watch for new or previous firmer wind transported snow mainly on the lee N to SE slopes below ridges.

New storm slab is likely where more than several inches of snow rapidly accumulates Sunday by the end of the day.

A slight warming trend should help to enhance new wind and storm slab layers on Sunday.

Weather and Snowpack

Two fair weather periods in January allowed surface hoar and near surface faceting to occur. These persistent weak layers were buried intact on Jan 3rd and 11th, but are no longer considered a persistent slab threat since several warm and wet systems have tested this layer and since it has been unreactive where it can still be identified in recent snowpits.

Dry weather with the warmest temperatures of the winter occurred February 7-10th with temperatures climbing into the 50's in most areas east of the crest.

Snow has dominated since then in the northeast zone and began to bury a crust there with about 2-3 feet of snowfall starting February 11th through today.

But rain and mild temperatures dominated in the central east and southeast zones last Sunday and Monday forming a newer crust there. Then the active and cooler pattern began to bury the crust in the central and southeast zones starting February 17th with about 6-9 inches of storm in the near and above treeline Wednesday to today.

Storm layers may linger in the recent storm snow but will have strengthened today.

Recent Observations

NWAC pro-observer Tom Curtis was at Blewett Pass on Wednesday mostly reported shallow new snow on a thick crust.

The North Cascades Mountain Guides sent a report Friday for the Washington Pass area and report that the February 11th crust is found at about 65-80 cm. Some but not all tests give hard sudden collapses with sudden propagation. Also some stiff pencil hard wind slab giving easy shears, hidden under about 10 cm of new snow, has been seen near some ridges.

The pro-patrol at Mission Ridge today reported pockets of ski triggered 6-14 inch wind slab during avalanche control on northeast to southeast slopes above about 5800 feet. These slab were releasing on the February 17th crust. Later today a skier triggered a 6-10 inch wind slab and was caught and carried but not injured in a northeast facing chute at about 6300 feet.