A strong, fast-moving cold front will sweep across western Washington and Oregon for the first day of fall on Sunday, bringing a combination of wet, windy and white weather from the coast to the Cascades.
In places such as Seattle and Portland, southerly winds sustained at 15-30 mph, with gusts of 35-45 mph, are possible as the front blasts onshore. Some of the higher elevations and coastal locations could have winds gust as high as 55 mph.
Winds of this speed can snap tree branches and bring them down onto power lines, causing sporadic power outages. These winds will also blow around any unsecured objects left outside, such as trash cans or patio furniture.
Rainfall across the region will average between 1.00 and 2.00 inches from Portland to Seattle. Some areas on the Olympic Peninsula and in the Cascades will have over 2.00 inches of rainfall. Some localized urban and small stream flooding is possible, as well as flooding in poor drainage areas.
Snow levels in the Cascades will start the day on Sunday at around 7,000 feet, but they will lower to around 5,500 feet for Sunday night and Monday. Snowfall accumulations of 2-4 inches are likely, especially above 6,500 feet.
If you plan to travel major interstates such as I-90 or I-5, be sure to drive slowly and maintain a safe distance between your vehicle and the one in front of you. The combination of wet, slick roadways and diminished visibility from vehicle spray and rain are an accident waiting to happen for anyone not paying attention to the roadway.
Some delays are possible at the airports, especially in the afternoon as heavy rain and low clouds make landings and departures a challenge.
In the higher elevations hikers should prepare for rain turning to snow. Be sure to have appropriate winter weather survival gear.
The rain and wind will diminish during the day on Monday, but there will still be plenty of lingering clouds and showers, with snow showers in the higher elevations above 5,000 feet.