This is a one beautiful longhorn beetle – a Banded Alder Borer (Rosalia funebris). Found it walking along Wynoochee Drive between Bald Hill Park and Fitton Green where there are big alders along the headwaters of Mulkey Creek. Probably a female since the antennae are slightly shorter than the body.
And now for the fun part. Turn the volume up a bit and try not to laugh:
Randy and Pam