The trickiest part of this problem was making sure where the Yakima Valley is. OK so it's generally around the city of the same name in Washington State.
Just for a place to work with, I picked the Yakima Valley Junior College, at the corner of W Nob Hill Blvd and S16th Ave in Yakima. The latitude in the middle of that intersection is 46.585° North. <u>That's</u> the number we need.
Here's how I would do it:
-- The altitude of the due-south point on the celestial equator is always (90° - latitude), no matter what the date or time of day.
-- The highest above the celestial equator that the ecliptic ever gets is about 23.5°.
-- The mean inclination of the moon's orbit to the ecliptic is 5.14°, so that's the highest above the ecliptic that the moon can ever appear in the sky.
This sets the limit of the highest in the sky that the moon can ever appear.
That doesn't happen regularly. It would depend on everything coming together at the same time ... the moon happens to be at the point in its orbit that's 5.14° above ==> (the point on the ecliptic that's 23.5° above the celestial equator).
Depending on the time of year, that can be any time of the day or night.
The most striking combination is at midnight, within a day or two of the Winter solstice, when the moon happens to be full.
In general, the Full Moon closest to the Winter solstice is going to be the moon highest in the sky. Then it's going to be somewhere near 67° above the horizon at midnight.
