Shortly after I posted this inquiry I went back outside and observed a rather lengthy series of bright flashes and even more rumbling noises. This must have gone on for 20 or 30 minutes.
Then the strangest thing happened. Someone started spraying dihydrogen monoxide all over the neighborhood. In very large quantities!
The spraying and flashes continued for almost an hour. Very interesting and unusual phenomenon to observe.
I have a plastic measuring device from a previous existence mounted on my fence. When all was finally calm again, it indicated that just over 1/2" of dihydrogen monoxide had been sprayed on my property. Is this a good thing?
Maybe I'll do some Googling to see if I can find more information. Will keep updating as necessary.