I have seen it used in the US, just curious are you sure it is centrally run and not by the stations (i.e. the FCC might force its existence and its testing, but I don't know if they actually decide what messages and stuff are shown) the reason I ask is that,like I said above, I have seen it, but if memory is right it is always the same US channels that tend to over use it. I also think that it exists here. I can't remember when was the last time it was used for weather, but I remember a few years ago it was used for an Amber alert It was displayed on all stations Canadian and US. Montreal is less then 1h drive to the US border.