Remote lightning detections displayed?

I was looking at the lightning strike display tonight on Weathertap to check out the storms training up through Arizona. The display of course uses the US Precision Lightning Network that I had always assumed only covers the continental US. In times past when I looked at it, it seemed to do just that.

Tonight, however, I notice that lighting is being detected not only well up into Canada and down into Mexico, but more surprisingly well out to sea, i.e. in a Wilma rainband in the vicinity of the Isle of Pines and somewhere well east of the Bahamas. Anyone know how dey do dat?

I mean... I know more or less how the detector net works.... [In fact I happened to be taking synoptic met at the University of Arizona when Dr. Krider and his students were first developing it. The little HP pen plotters in the fax/tty machine room would go chonk-chonk to mark an 'X' whenever a CG hit in the region. This was "a few" years ago. :roll: ]

But I don't know how they can detect spot-on so far out to sea. Does anyone know how? Do they perchance have detectors on buoys or satellites now?
I don't know the specifics on the USPLN, but I'm pretty sure they have CG sensors on some of the Carribean islands as well which would explain the coverage you're seeing. The low frequency used to identify cloud-to-ground strikes can propogate in upwards of 500-1000 miles providing decent coverage in offshore areas, despite a sensor not being located anywhere near there. Although, the exact accuracy of the CG placements in these instances is error prone.