A couple weak shortwaves are forecast to pass over the forecast area today through Thursday, with periods of precipitation. Thursday night through Friday night, a more robust upper low and attendant frontal system will develop offshore in the northeast Pacific, Bringing more rain. There is freezing rain potential in portions of north-central Oregon and south-central Washington Thursday night through Friday.
Saturday through Tuesday, An upper trough will be over the Pacific Northwest at the start of the period. This trough will move eastward and out of the region during the day on Saturday. This system will depart on Monday as the flow becomes more northwesterly which will bring in drier air as a large upper ridge begins to build in. Snow levels are expected to be 3000 to 3500 feet across the Washington Cascades Saturday and Sunday and 3500 to 4500 feet elsewhere.
TRI-CITIES;
Thursday: 43/35
Friday: 42/33
Saturday: 48/36
Sunday:…..