INFO FROM SIDC - RWC BELGIUM 2013 Dec 08 12:48:12

The X-ray curve is situated near the top/bottom of the B/C-level. C-flares
are very likely, the probability for M-flares is around 20%. The December 7
M1.2 flare (07:29UT peak time) from NOAA AR 1909 was associated with a CME.
CACTus determined it as a (partial) halo CME with a speed around 900 km/s.
The bulk of the plasma is ejected under the ecliptic plane. The side of the
CME may impact the Earth. This glancing blow can possibly arrive late
December 9, early December 10 and may result in geomagnetic disturbances. 


Late December 7, a co-rotating interaction region (CIR) arrived. The
density increased gradually together with the magnetic field. The
z-component fluctuated strongly, even to -25nT which resulted in a
planetary K of 6 and 5 and local K Dourbes of 5 and 4 early December 8.
Following the density increase and slow decrease, the solar wind speed
increased gradually. The CIR and fast solar wind is possibly linked with
the coronal hole which reached the central meridian on December 3.
 
A shock is visible on ACE data on December 8, 7:30UT: the solar wind speed
increased from 500 km/s to around 650 km/s, the temperature, density and
magnetic field dropped. This fast reverse shock is possibly linked with the
filament eruption of December 5. The geomagnetic impact will be limited and
smaller compared to the CIR because of the drop in magnetic field strength.
Bz rotated from negative (-5nT