For painters searching for a medium, a show opening tonight at Umpqua Community College will suggest they try pastels, pastels and more pastels. Hosted by the Pastel Society of Oregon, the 18th Biennial Juried National Exhibition will bring a sampling of national works in pastel to the Umpqua Valley. There will be 67 pieces by 37 artists, including 12 artists from Roseburg. Most of the pieces depict landscapes and animals, though there will be a range of subjects. The show will hang in the Whipple Fine and Performing Arts through Oct. 25. Watercolor, oil and acrylic proponents are likely to …