The Memorial Day weekend forecast is always an important one. Yes, many people will be on the the road this weekend, and parades, picnics and other outings are popular. The weather is generally not reliable yet, even though we have usually had a taste of warmth by this time. And many weather-related tragedies have occurred during this period: from avalanches, high and fast water in rivers from rapid melt, and even snow white-outs on high volcanic peaks.
This year we will get the worse weather out of the way early, as a moderate front moves through Washington and northern Oregon on Friday morning and early afternoon (see 3-h precipitation ending 11 AM Friday below). We need the precipitation, there hasn't been anything significant for over a week.
Saturday will be a partly cloudy day, with considerable clouds over western Washington. A few light showers will remain. To illustrate, here is the precipitation forecast for the 3 hours ending 2 PM.
Want guaranteed sun? Head east of the Cascade crest, as illustrated by the cloud forecast for 11 AM Saturday. Saturday temps getting into the upper 60s away from the water over western Washington.
Sunday will start dry, but a moderate front (and a fairly strong offshore low) will approach late in the day (see precipitation forecast for the 3-h period ending 5 PM). Rain will reach the coast during the mid afternoon, but the interior should remain dry to around dinner time. Eastern Washington will be warm as will be the Willamette Valley (both in the 70s,see temperature map at 5 PM below).
The front will go by on Sunday night and Monday there will be scattered showers and considerable cloudiness. No big winds during the weekend, although it will get blustery along the Washington coast on Sunday afternoon. Enjoy the weekend.