Total posts : 45366
It seems highly unlikely that a part 15 FM signal would duct and have enough strength to cause any problems. By the time it travels into and through the duct it has gone so far that it will be well below noise. As far as interfering with a DX signal coming into your area goes the DX signal is not in its intended service area and won’t be there long so it shouldn’t be a problem.
Temperature inversions also cause some interesting things to happen on the amateur radio 2 meter band. I recall while living in Cincinnati that I could work the repeater in Asheville, NC with my 2 1/2 watt hand held. The band stayed open for several hours.