Update – The storm watch has been continued to a second day. Solar wind speeds arrived later than predicted. Aurora will continue to be possible over the next 24 hours:
Northern Lights Now – SWPC has issued a geomagnetic storm watch for Thursday, February 23. This means KP values could exceed 5 with aurora visible in higher latitudes. Viewing conditions will be favorable with an almost new waning crescent Moon. The confidence on this storm is a little lower than other recent storms, but is high enough to merit a watch.
The potential aurora is due to the combination of a coronal hole that was pointed towards the Earth on February 20, and a filament eruption that produces a CME from just North of the coronal hole.
The coronal hole, pictured below, is likely to produce solar wind speeds at Earth in the 500-550 km/s range. The winds could pick up anytime between 20:00 GMT on the 22nd and 8:00am GMT on the 23rd. Once wind speeds increase, if the Bz shifts southward (negative), it will indicate northern lights activity is about to increase. Monitor solar wind speed and current Bz on NLN’s DSCOVR Solar Wind Data Page to know when aurora activity is about to increase.
The eruption was from a filament just to the north of center disk and February 19th. Watch the eruption in the animatedGIF below. The plasma cloud is visible shooting out, mostly northward, from the location of the filament. If the material from that cloud is pulled into the solar wind, it will be accelerated and pushed toward Earth. If that happened (forecasters can’t know for sure until the solar wind arrives) it could enhance the aurora activity by increasing the plasma density and accentuating the shifts in the Bz.
This is a slightly lower confidence prediction because the predicted solar wind speed is moderate, and there is a good chance that none of the plasma directed was toward Earth. The plasma may move off into space well above Earth’s North Pole. The image above showing the eruption does appear to show most of the material ejected moving to the north.
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):
Northern Lights Now – There have been several notable eruptions on the Sun since November 4th. As of now, models are not indicating G1 storming, but with the combination of events, and models predicting KP=4, it is not out of the question that there may be some G1 storming between 11/8 and 11/9.
Early on the 4th a filament erupted from the SW portion of the disk. There is a clear CME lift off, but it appears to be headed mostly to the South and West of the Earth-Sun line. Here is an animatedGIF showing about 4 hours in AIA 304 with showing the filament erupting
About 6 hours later, a small B2.2 flare happened around an unnumbered region in the NW quadrant. Just after this low level eruption, a wave is visible traveling southward through the corona. Dimming was also seen in automated CME detection during this flare. Often, dimming is indicative of a launching CME, but there was no clear sign of a CME on LASCO. If this flare did launch a CME towards Earth, it will be a stealth CME. This flare was optical only and did not register on NLN’s Solar Flare Browsing page. In this video, the first half shows the full disk, the second half zooms in on the actual flare.
Finally, a pair of filaments erupted early on the 5th. The first, bigger one launched from the NW quadrant of the Solar disk from a location just north of the area of the B2.2 flare. This filament also showed what looked to be a launching CME on AIA 304, however most of the material looks to be traveling North and West. The other filament erupted on the East of the disk at nearly the same time and is much smaller. They are both visible in this AIA 193 imagery, the second is just barely visible.