Ions from one of the strongest coronal mass ejections (CME), or solar storms, since 2005 are expected to hit the Earth's atmosphere beginning at about 9am EST (1400 GMT) on Tuesday, according to the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC).. The SWPC forecast is for Moderate (G2) level geomagnetic storming with G3 levels possible (the scale tops out at 5). This is expected to make the aurora borealis visible at lower latitudes, and possibly cause interference for satellite communications.
http://www.swpc.noaa.gov/