PA0O (440km) has been spotted 8 times since 1342z today on 10m WSPR. This is an odd distance and I am unsure of the propagation mode. It would be very short Es skip (and it is late in the Es season) and I would prefer to think this is tropo. He has been copied all afternoon. However, with HF F2 conditions good on 10m WSPR I guess it could be F2 backscatter?
No USA stations have been copied on 10m WSPR since KZ8C (6290km) at 1656z, whereas PA0O has been spotted several times since, tending to suggest tropo.