I usually try to answer "simple" question like this for myself, or with the assistance of online dictionaries. But I came up blank on this one. Found a few discussions on other language forums, but no real consensus. The question came up because of a large storm moving through Arizona today.
I hear thunder.
And so I say: It is thundering outside.
I also see lightning. So what's the verb form for that? It is (what?) outside.
I've always used lightning as both a noun and verb. Kinda like building and painting serve as both. But the dictionaries I checked listed lightning as an intransitive verb, and doesn't the "It" qualify as the object the verb references?
To say "It is lightninging outside." just sounds wrong. Am I rightning?
In my 15 minutes of research I have found disagreement but I see near consensus that lightning is not a verb. To express the action of lightning we should say, "lightning flashed." The best argument otherwise is the extremely common expression, "It is thundering and lightning." This all probably is no help, but I believe lightning should not be used as a verb. My opinion.
"We're in/having a thunderstorm." You could call it a "lightning storm" as well: I find the former to be more common, so perhaps the latter would have a more striking impact.
I've never, of course, used it formally, but since I was a kid I've never hesitated in casual conversation to say, "lightninging."
I am with you. I do not hesitate to use lightninging in informal contexts. In formal contexts I would use same form of strike , flash, or some such, in conjunction with the noun.