Thanks guys, I appreciate the replies. I'll try to provide some more info and some specs.

First, my memory failed me... it's a 6" post.

The worst of the splitting is on the southern-facing side of the post, which is covered by the gutter downspout, so pics are a little hard to get straight on without removing it.

I checked some of the worst spots for depth and came up with 1 3/8".

The post itself isn't supporting a lot of weight. The patio has structural walls on two sides that intersect, and the post is on the outer corner with just roofline above.

Here are pics (apologies in advance for the size and quantity).





Here are the 2 sides that were previously caulked and repainted.




Western-facing side that has not been repaired previously


And here's the worst of the checking, which is almost exclusively behind the downspout... sorry for the angles.