There were two separate coronal mass ejections (CMEs) from the sun on Wednesday, December 16th, and they are headed towards Earth and will arrive during the next couple of days. The first CME was associated with a C6 X-ray flare which occurred at 0903 UTC (0403 ET) and the second was from a coronal disruption in the southeast quadrant of the Sun. While the sun has been relatively quiet in recent weeks and is in the midst of one of the weakest solar cycles in more than a century, occasional solar storms are still quite possible. In fact, one of the strongest solar storms ever that is now known as “The Carrington Event of 1859” took place during a relatively weak solar cycle. [For more information on “The Carrington Event of 1859” click here: http://www.vencoreweather.com/blog/2015/09/08/900-am-even-weak-solar-cycles-can-produce-super-solar-storms-the-carrington-event-of-1859].
The first CME that was ejected from the sun on Wednesday is likely to arrive in the Earth’s upper atmosphere late Friday, December 18th, bringing minor (G-1) geomagnetic storm conditions with it and then following in close succession, the second CME is likely to arrive early on the Saturday the 19th. The second CME – a bit stronger than the first - is predicted to increase geomagnetic activity to moderate levels (G-2). The potential effects of a moderate geomagnetic storm (G-2) are as follows as outlined by NOAA:
Power systems: High-latitude power systems may experience voltage alarms, long-duration storms may cause transformer damage.
Spacecraft operations: Corrective actions to orientation may be required by ground control; possible changes in drag affect orbit predictions.
Other systems: HF radio propagation can fade at higher latitudes, and aurora has been seen as low as New York and Idaho (typically 55° geomagnetic lat.).
NOAA’s Space Prediction Center in Boulder, Colorado runs a forecast model to provide advance warning of solar wind and Earth-directed CMEs that cause geomagnetic storms. Solar disturbances have long been known to disrupt communications, wreak havoc with geomagnetic systems, and to pose dangers for satellite operations. The latest forecast from this physics-based prediction model of the heliosphere shown above depicts the arrival of plasma associated with the first CME late Friday (indicated by the arrow and the Earth is represented by the small green circle). We are currently more than six years into the current solar cycle #24 which began after an unusually deep solar minimum that lasted from 2007 to 2009 and had more spotless days compared to any minimum in almost a century. [For more on solar cycle 24 click here: http://www.vencoreweather.com/blog/2015/04/30/845-am-the-sun-is-now-virtually-blank-during-the-weakest-solar-cycle-in-more-than-a-century ].
Meteorologist Paul Dorian