Northern Lights Now – The Coronal Hole High Speed Wind Stream (CH HSS) that prompted the Jan 6, 2016 G1 #aurora watch started arriving at Earth just past Midnight GMT On Jan 6. Rather than updating the original article, NLN will be posting updates to this blog post instead, please come back soon for more updates!
13:44 UTC January 7, 2015 (08:45AM EST)
Solar winds are now gradually subsiding. This period shows too much variability in the Bz to produce wide-spread aurora.
23:45 UTC January 6, 2015 (18:15PM EST)
Around 21:45 UTC the Bz shifted softly to the south with measurements in the -2 to -4nT range at the ACE satellite. This is very mildly south, but it lasted for about 75 minutes. It was enough to start an aurora show in Finland. Here’s a skycam framegrab taken from the Sodankylä Geophysical Observatory from about an hour after the negative Bz was measured at Earth:
17:15 UTC January 6, 2015 (12:15PM EST)
Solar wind speeds have decreased slightly over the last 12 hours to around 525-550 km/s. In the last 2 hours readings have become more volatile. The Bz has stayed consistently north. As such, there have not been any signs of aurora. It is still possible that any transients or small CMEs traveling along the wind stream could push the Bz one way or the other. If that happens, there will be about 45 minutes of lead time.
04:15 UTC January 6, 2015 (11:15PM EST)
Just after midnight UTC solar wind speed started increasing. Reading moved up from 450km/s to 625km/s at the same time there was a 90 minute period of south point Bz. Together, these events pushed ground based KP monitors to register a KP of 4.67 (G1) for the 00:00 – 03:00 period. Wing KP responded by over-estimating the predicted 60 minute KP with a reading of 5.67 even though the Bz subsequently shifted to the north. The is expected to be a long duration high solar wind speed event, so there are ample opportunities for more aurora over the next 24-36 hours. Here’s the ACE data from SWPC with the increase in wind speed annotated:
Through this, there was a brief period where we’d have expected to see Aurora at lower latitudes. During that window this tweet came in from Scotland marking the first photographed aurora from this storm:
— CallanishDD (@CallanishDD) January 6, 2016