The first squealls of a geomagnetic storm described as "severe" by space-weather forecasters swept past the Earth Thursday . The 1.6 million mph impact by the cloud of ionized gas and electro-magnetic energy rattled electric power grids in the Northeast, and at least one commercial satellite briefly lost its bearings. The storm began Tuesday with a pair of "X-class" solar flares, the strongest ranking, X-ray emissions from the flares blacked out shortwave radio communications for up to an hour.