Heavy Snow in East Slopes of the Washington Cascades, Washington

A Cocorahs observer 17 miles NW of Roslyn, WA measured 17 inches of new snow in a 24 hour period ending at 0700 PST on Jan. 3rd. A public report indicated 12 inches of new snow had fallen 12 miles NW of Tieton, WA at 1000 PST on Jan. 3rd.

A prolonged period of northwest flow over the Pacific Northwest guided several rounds of moisture advection across the mountain zones, leading to upslope moderate to heavy snow showers nearly each day. Meanwhile, surface frontal systems and a series of shortwave troughs in the flow aloft produced moderate to heavy snow as well as some periods of freezing rain across the lower elevations. Strong winds were also produced as a result of these shortwave troughs and surface frontal systems at the beginning and end of the prolonged winter weather conditions. During this extended period of winter weather, the I-84 and several state and US highways in Oregon and Washington closed for extended periods of time due to increased traffic accidents from ice and/or moderate to heavy snow accumulations on roadways.