Interesting signal reports from my mobile setup

Yesterday, at lunchtime, I decided to test out the HF setup in the car, which I have recently reinstalled. I gave out a CQ on 14.005 with 100 watts through my roof-mounted Watson Multi-ranger antenna. I didn't actually want to make any contacts. I was happy enough just to look at the signal reports on the Reverse Beacon Network. And that's when it got really interesting!

As you can see from the photo on right, I was parked against a wall with a fence on it, and behind that is a big factory unit that it perhaps 30 feet tall. The front of my car is facing roughly east-southeast, so the factory is pretty much blocking me to the west-northwest. And what was my best signal report on the Reverse Beacon Network? VE2WU in Canada, which is where my signal should have been worst. Perhaps the fence was reflecting my signal strongly onto the long path? I had good reports from Belgium and Germany too, which should not be so surprising. But 54 dB snr from Canada is a damn good report, the sort of thing I mightn't even see with my hexbeam and 400 watts pointing directly to Canada!

Perhaps one of my readers can shed some light on what might have made my signal to Canada so strong?