Mountain Weather Forecast

Weather Synopsis for Wednesday & Wednesday

A deep Pacific upper level and surface low is moving E-NE on Wednesday morning in the direction of the Queen Charlotte Islands and is located approximately 700 miles off the coast of Oregon. It sits north of a strong E-W jet. The Pacific Northwest lies near the western edge of a broad, shallow ridge centered to our east and the deep upper trough and low pressure to the west.

Associated with the low pressure offshore, a warm front is lifting northward over the Pacific Northwest this morning bringing a relatively narrow band of light to occasionally moderate rain and snow to the Olympics and central/north Cascades. Temperatures are borderline in the mountain passes, but easterly flow will keep much of this precipitation in the form of snow in spite of anticipated warming aloft during the late morning hours. By noon, most precipitation will have lifted north into Canada.

During the early afternoon hours on Wednesday, the associated cold front will bring rain to the Olympics and by the late afternoon hours the frontal rain band will begin to bring rain and high elevation snow to the west slopes of the Cascades with the cold front crossing the Cascade crest just before midnight. The frontal passage will usher in a cooler air mass on a SW flow and snow levels should drop to pass levels by Thursday morning.

On Thursday, The large low pressure center will begin to fill (become less deep) as it sits and spins near the southern end of the Queen Charlotte Islands with an associated trough 500 miles offshore of our coastline. A moist SW flow should continue on Thursday and Thursday night as the trough digs southward and slightly east. Significant snowfall is expected and particularly high totals can be expected in areas favored by the SW flow (Baker and Rainier) with lower water amounts expected in the Cascade Passes.