It is quite possible. I used to use packet radio on 144.45MHz, and when the conditions were right I could reach a BBS ~200km away. That's not terribly exciting, but both stations were pretty low to the ground, not very powerful or directional, and definitely not in line of sight.
For reference, according to wikipedia, if one station was at sea level and the other about 1500m above, you'd expect line of sight to be around 160km.
Similarly, around the same time of year (January or so) but less frequently we used to get VHF TV interference from a station on the same frequency but more like 1000km away (if I'm remembering the source station right, it was a long time ago), strong enough to interfere with the more local transmission.
For reference, according to wikipedia, if one station was at sea level and the other about 1500m above, you'd expect line of sight to be around 160km.
Similarly, around the same time of year (January or so) but less frequently we used to get VHF TV interference from a station on the same frequency but more like 1000km away (if I'm remembering the source station right, it was a long time ago), strong enough to interfere with the more local transmission.
Radio+atmospheric effects can get weird.