As best as I can tell from the pics, looks rather more like pseudomonas (bacterial blight) than typical winter cold damage. This cultivar of JM is extremely prone to this pathogen. It is often associated with aborted buds, tip dieback and eventually blackened stems or bark and is very common in wet springs.

You do want to prune out the affected portions, cutting back below any infected growth to viable wood, generally several inches beyond what looks like healthy growth, but always to a growth point or node. Don't leave stubs! And sterilize your pruners between cuts to avoid spreading the problem.

If persistant, the problem can prove fatal but if caught early, there is a good chance of recovery. You might want to research Pseudomonas syringae pv. syringae as it applies to Japanese maples for other methods of control.

That would be my first thought also, without even looking at the pictures - based on what I see in my area.

Ouch that's bad news. Thanks for the diagnosis. I tried to read up on Pseudomonas syringae. It seems as though, as you've suggested, the most important thing to to pick a dry day and prune back as much of the black/dead wood as possible. I'll do that later today. I've also read that it can help to spray with a bordeaux mixture in the fall and early spring. From what I understand its too late to spray now since the maple is already leafed out so there is too much risk of a phytotoxic reaction.

Do you have any thoughts as to whether it'd be beneficial/safe to spray the foliage and trunk now with a light application of something systemic like phyton 27 that isn't supposed to leave a residue on the foliage? Thanks again for all your help.

Thanks again for the help. I'm including a few more pictures. After closer inspection, what I'd refer to as the central leader appears to have some fairly large blackened areas on the upper 1/5th of the tree. Just to be clear, before I prune out this sizeable branch, can please confirm that removing this area now is my best option for the long term health of the tree?

Thanks.

-Chris