North American weather patterns look decidedly North American at the
moment: http://weather.unisys.com/images/sat_sfc_map_loop.html
These fronts always follow the outline of the east coast, I suppose
that is to be expected.

The set out of the storms on here though:
http://www.spc.noaa.gov/climo/reports/yesterday.html
..... how do they know the shape of the east coast?