Northern Lights Now – High speed wind from the coronal hole mentioned in the previous NLN post is expected to arrive sometime on October 24 and should induce G1 and G2 storm conditions through the 26th. SWPC has issued storm watches for all three days with G1 watches on the 24th and 26th and a G2 storm watch on October 25. This means KP levels could reach 5.67 or more.
Models are predicting an extended period of elevated solar winds reaching as high as 650km/s for all three days. The initial winds will arrive with a CIR (co-rotating interaction Region) where densities are higher and the magnetic fields are more complex. This means you can monitor the progress of the arriving wind stream – it will show up as proton densities as measured at L1 by DSCOVR will rise. Once Earth is in the body of the high speed solar wind stream, density decreases and winds increase.
Current forecasts show geomagnetic activity reaching G1 levels (KP=4.67 and above) the second half of Oct 24, then reaching G2 (KP=5.67 and above) on the first part of Oct 25. Activity should slowly decline over the following 36 hours, but there may be spike of activity if the magnetic fields line up just right.
As an update to the features in that previous post, the filament did lift off, but was subsequently reabsorbed, so it did not generate a CME. The active regions rotating into view on the East limb seem to have lost their magnetic complexity. Space Weather forecasters are not expecting they will be active flare producers in the next several days.
Northern Lights Now – After somewhat quiet space weather since the last round of aurora October 9-13, there are several features to watch again. A coronal hole is pointed towards Earth and has prompted a G1 Geomagnetic Storm watch for October 24. There is a filament to the west of the coronal hole that looks like it could lift off soon and there is an active region rotating on to the east limb that was responsible for a large backsided CME just a couple days ago. Let’s take them one by one
The large dark area in the center of the imange is a large coronal hole pointed towards Earth right now. It has increased in size since the last rotation and is likely to bring high speed solar wind starting in three days. When it arrives there is a good chance KP values will cross into the G1 storming range. SWPC has posted a geomagnetic storm watch for Tuesday October 24.
Just to the north and west of the coronal hole there is a filament that is looking like it may lift off soon. If it does lift off, there is a chance it could produce a CME. This is worth monitoring. It is easiest to see the filament in AIA 304 as in the animated gif here:
New Active Region
Potentially the most promising area of interest is the active region rotating into view on the southeast limb. This is the return of AR2674 (Aug-Sept rotation) and AR 2682 (Sept-Oct rotation) after it traversed the backside of the Sun. It should be numbered AR2684 or AR2685 later this evening.
This AR was responsible for CMEs early on Oct 18 and on October 21. The CME yesterday was from an M1.1 flare that happened just over the eastern limb. This region has shown activity over the last several days that hints that it is magnetically unstable. It seems likely that it will continue to producing flaring and possibly more CMEs.
Northern Lights Now – The Space Weather Prediction Center in Boulder Colorado has issued a G1 storm watch for October 11-12 indicating the potential for KP values at or above 5 and active aurora. This is due to the expected high speed solar wind coming from a large northern hemisphere coronal hole.
Models, such as the WSA-Enlil below, are predicting that the first phase of the storm should start midday on Tuesday as plasma densities rise to around 15 p/cm3. 6-12 hours later, solar wind should pick up and may reach 550 km/s. The coronal hole covers a large area longitudinally, so once the wind speed readings increase, they may remain elevated for over three days. It would not be surprising to see the G1 watch extended into a third day.
As of this writing, the periods of KP=5 and above are predicted to start midday on Oct 11 and continue on and off throughout Oct 12.