Washington Post 
January 23, 2012
Fast on the heels of a solar storm that delivered a glancing blow over the weekend — triggering bright auroras in Canada and Scandinavia — the sun released an even more energetic blast of radiation and charged plasma overnight that could disrupt GPS signals and the electrical grid Tuesday, especially at high latitudes, space weather experts warned Monday morning.
Already, the storm could be disrupting satellite communications as streams of radiation from the sun bounce across the Earth’s magnetic field, which extends above the surface into space.
“With the radiation storm in progress now, satellite operators could be experiencing trouble, and there are probably impacts as well to high frequency [radio] communications in polar regions,” said Doug Biesecker, a physicist at the Space Weather Prediction Center, part of the National Oceanic and Atmospheric Administration in Boulder, Colo.
Such radio blackouts can force airlines to reroute flights between North America and Europe or Asia.