On Thu, 17 Feb 2011 07:56:19 PST, "andrew.wallace" said:
The biggest flares can disrupt technology, including power grids, communications systems and satellites.
Better references: http://www.spaceweather.com/ and http://www.swpc.noaa.gov/: 3-day Solar-Geophysical Forecast issued Feb 16 22:00 UTC Solar Activity Forecast: Solar activity is expected to be moderate with a chance for an isolated major flare for the next three days (17-19 February). Region 1158 is expected to produce more M-class flares and still has the potential for producing an M5 or greater x-ray event. There is a chance for isolated M-class activity from Region 1161. Geophysical Activity Forecast: The geomagnetic field is expected to be predominately quiet on day one (February 17). An increase to unsettled to active conditions, with a chance for minor storm periods is expected late on day one into day two (18 February). The increased activity is forecast due to the expected arrival of the CME associated with the X2 flare that occurred on 15/0156Z. Day three (19 February) is expected to be quiet to active as the disturbance subsides. *yawn*. "active" to "minor storm". Move along, nothing much to see except some aurora. :)