Mountain Weather Forecast

Weather Synopsis for Friday night through Sunday

The dry pattern the Pacific Northwest enjoyed this past week winds to a close. A weakening front system sends the majority of its moisture and energy north of the Canadian border but brings increasing clouds overnight with some light rain and snow impacting the Olympics and Mt. Baker areas in the early morning hours. The moisture sags gradually south and east on Saturday, with light amounts as far south as Snoqualmie Pass. Snoqualmie and Stevens Pass should expect less than an inch of snow with Mt. Baker picking up 1-2". Low relative humidity values should allow the atmosphere to cool significantly as moisture arrives, allowing for snow down to around 3000 ft. The fizzling front exits by mid-afternoon with a mix of sun and clouds expected in the late afternoon hours across the region.

After a mostly dry evening Saturday night, a strong system with a well-defined warm front, cold front, and detaching low should begin to spread light rain and snow back in the early morning hours on Sunday. Widespread heavy rain and snow Sunday morning should accompany the warm front and cold frontal passages in rapid succession. Light E flow developing as the precipitation arrives should keep the Passes mainly snow through mid-morning, but as the cold front passes there may be a bump in snow level briefly above Snoqualmie Pass level before the snow level drops by Sunday afternoon as moderate to heavy postfrontal moisture moves in on a westerly flow. The post-frontal portion of this storm is quite significant and longer-lasting. The detached low should track toward southern Vancouver Island by late Sunday, enhancing snowfall late in the afternoon. The system should also bring widespread moderate to strong 5000 ft winds from the early morning hours Sunday through Sunday afternoon and widespread very strong to extreme winds in the alpine that peak Sunday morning with the frontal passages.