We've talked in the past about skywave propagation, but it's cool when you heard about real-world examples of it. Recently I've gotten several emails from "DX'ers" (Distant Reception enthusiasts) in Europe saying they've been able to hear Latino Public Radio on 1290AM all the way across the Atlantic!
We have put a temporary setup in place with a donated 30 watt transmitter on loan (with the antenna array's gain factor of 2.1, it's really more like 63 watts of Effective Radiated Power), and a special radio that's tuned to 102.7FM (there's a high-gain FM antenna on the rooftop tower) and puts out the composite signal directly into the new transmitter. This effectively makes 91.5 into a "repeater" of 102.7FM.
UPDATE 11/5: Thanks to a fellow engineer who informed me there is a pirate broadcasting on 102.9FM and that is likely the source of the interference people have reported (see below). Quite possibly the atmospheric changes made it worse, but the bulk of the problem is likely the pirate.