Can hurricanes impact weather in the Pacific Northwest?
Hurricanes don't move into the Northwest. The cold water causes them to die. Now, a strong storm can influence other pressure systems, telegraphing influence at a distance. Scientists have talked of the butterfly effect-the idea that turbulence from a butterfly's wing beats can multiply and eventually have a discernible influence on weather. If that's indeed the case, it's not hard to see how hurricanes thousands of miles away could intensify/weaken or speed/slow/re-direct low pressure systems off our coast.
However, we've seen more direct influence. The Columbus Day storm of October 1962 began life as a Typhoon over the Philippines, which then moved east across the Pacific and curved toward Washington and Oregon. It no longer was a Hurricane-it no longer drew it's energy from warm tropical waters, but transformed into an extra-tropical cyclone, drawing its' energy from sharp contrasts in temperature in the upper atmosphere and from strong winds aloft...elements that would ordinarily weaken and then kill a hurricane. So forecasters keep a very close eye on hurricanes over the Pacific.