FAST WARNING 'PRESTO' MESSAGE  from the SIDC (RWC-Belgium) 2016 Sep 27
19:46:07

The arrival of the fast solar wind, from the coronal hole in the northern
hemisphere with a long latitude extension, has induced disturbed
geomagnetic conditions this evening. The combination of the fast solar wind
(speed of about 600 km/s) and the intervals of the negative value of the Bz
component of the interplanetary magnetic field (down to -9 nT), has caused
the moderate storm conditions. The Potsdam station reported K=6, and NOAA
reported Kp=6. We expect disturbed geomagnetic conditions to continue in
the coming hours.