NOAA’s Space Weather Prediction Center (www.swpc.noaa.gov) has a BOLO out on this one. Expect “wonky” band conditions…
The geomagnetic storming watch for 30 December has been upgraded to a G3 (Strong), with a G1 (Minor) storming watch still in effect for 31 December. These watches are in response to consistent WSA-Enlil modeling results and SWPC forecasters’ determination that a coronal mass ejection (CME) impact is likely just after mid-UTC day on 30 December with residual CME effects continuing into 31 December. The CME impact may cause a sudden impulse geomagnetic response at Earth, likely resulting in the G3 conditions. The CME was associated with a long-duration M1 flare (R1-Minor radio blackout) that peaked at 1245 UTC (0745 ET) on 28 December. Keep checking the SWPC website for continued updates.
Graphics and more here: http://www.swpc.noaa.gov/news/g3-strong-geomagnetic-storming-likely-30-december