Northern Lights Now – The large coronal hole that was pointed directly towards Earth on May 12th and 13th combined with recent solar disturbances prompted space weather forecasters to predict there will be an extended period of aurora activity the third week of May. The Space Weather Prediction Center (SWPC) issued storm watches for three consecutive days with a G1 watch posted for May 16, and G2 watches posted for both May 17 and 18. A G1 storm watch means KP values will likely exceed 4.67 during the 24 hour period, a G2 storm watch means the KP will likely exceed 5.67.
The coronal hole responsible for the expected activity stretched from North to South on the solar disk on May 13. In the image below, the coronal hole is the outlined darker area at the time it was directed towards Earth. High speed solar wind exiting from that region should arrive at Earth around May 16. As it arrives, expect solar wind speed readings from DSCOVR to increase, possibly to as high as 600 km/s. As the higher wind pushes on Earth’s magnetosphere, KP will read higher and any aurora will be stronger during periods of negative Bz.
After the initial coronal hole impact, there are two additional features that should impact Earth this week. Part two of this storm will be the arrival of a slow moving CME that launched from the southern hemisphere of the Sun on May 13. This CME is visible on LASCO C2 and C3 imagery, but it is faint. There is a decent chance it will miss Earth entirely to the south and we may see nothing from it. But it may also arrive at Earth as a glancing blow. This is a low confidence forecast, but if it does hit there could be G2 storming due the the magnetosphere already being activated by the initial coronal hole. Here’s an animatedGIF of the CME lauching as seen by LASCO C3:
Finally the third portion of this storm is most promising and is expected to impact Earth on 5/19 and 5/20. This second coronal hole produced great activity on the previous rotation in April. NLN will keep you updated with more information about this CH as it’s structure becomes evident.
It appears the CME missed Earth, probably to the West and North. It is unlikely at this point there will be any aurora storming tonight.
Northern Lights Now – The CME from the November 5 filament eruption is now expected to arrive at Earth late on Nov 8 and produce G1 storming. SWPC has issued a G1 geomagnetic storm watch. This forecast is lower confidence and more variable than usual. The current predicted timing shows that the period of KP=5 or higher is likely to happen at the end of the UTC day (or just after sunset on the US East coast and around midnight in Europe)
This forecast is low confidence because the majority of the CME is likely to go to the north and west of Earth. If Earth is hit, it will likely be a glancing blow. Further, it is impossible to predict the orientation of the cloud of plasma. If it happens to be oriented with a strong Bz south component, the KP could reach values higher the G1. If it is oriented with a strong positive Bz component, it’s unlikely KP values will read higher than 3 or 4. This is a classic wait-and-see storm.
Here is the WSA-Enlil model output from SWPC. It shows that when the CME arrives, it is likely to have a high proton density. This high proton density, at the same time as increasing solar wind are the primary motivations for issuing the G1 watch (click image for full size):