The main weather feature to affect Portland will be a low pressure system moving slowly across the Pacific toward the Northwest coastline. This will push a front through the Portland area on Saturday night. Most of the rain with this front will stay offshore or just near the coast, and rain will decrease as it moves inland. Still, there may be some sprinkles that reach Portland on Saturday night and Sunday. I don't think there would be enough rain to even measure a hundredth of an inch, if it happens at all. The front will also cause a wind shift from south of Friday and Saturday to west on Sunday.