Northern Lights Now – The second, larger, coronal hole mentioned in the previous NLN post is now pointed directly towards Earth and has prompted the SWPC to issue a new G1 geomagnetic storm watch for Wednesday September 27.
High speed solar winds are expected to arrive in the second half of Wednesday and May persist through Friday. It would not be surprising to see the storm watch extended another day. G2 storming is also possible during this storm. Stay tuned!
Northern Lights Now – It has been two weeks since the X-class flare that active region 2673 released as it rotated out of view on the western limb. In that time space weather and aurora activity on Earth has been slowly waning. As that active region rotates back into view it will be renumbered, probably as 2682, and space weather forecasters will be watching to find out how it’s magnetic structure has changed. In addition to the returning active region, there are two coronal holes that may impact Earth’s Aurora activity over the next 7-10 days.
A small coronal hole was pointed towards Earth on Sept 21, 2017. Notice in the AIA 211 image below that the majority of the coronal hole is to the south of the solar equator. This time of year, the earth is actually about 7 degrees north of the solar equator. The size of this hole and it’s location to Earth’s south decreases the magnitude of anticipated impact. There is a slight chance for KP4 or KP5 on Sept 24 as the high speed wind from the hole travels near Earth, but SWPC has not issued a geomagnetic watch
A second, bigger, coronal hole is approaching the Earth strike zone and will likely have a bigger impact on Earth’s geomagnetic activity September 27th to 30th. This coronal is in the northern hemisphere and has a history of producing high solar wind speeds at Earth on it’s previous rotation. The hole has developed a southern “arm” that crosses the Solar equator. The hole is now “transequitorial,” another indication that Earth will likely be in the high speed wind stream. It seems likely this will prompt a G1 or possibly G2 storm watch later this week.
The Return of AR 2673
The large complex active region that blasted 3 X-class flares and numerous M-class flares two weeks ago is completing it’s rotation around the back side of the Sun. While it was on the opposite side of the Sun, LASCO detected at least one major CME from it, but it his been less active over the last several days. As it rotates into view, forecasted will get their first glimpse of whether it has maintained it’s magnetic complexity.
We won’t know until 24-48 hours from now, but if it is still complex, there could be additional M-class flares over the next week. Stay tuned to find out!
Northern Lights Now – The expected G1/G2 storming from the coronal hole pointed towards Earth on Sept 11 arrived late on Sept 13. It induced a period of fast solar wind, strong Bt and G2 storming. The timing was good for our aurora hunting followers in Northern Europe who had clear skies.
At the onset of the storm, Bz was strongly (-15 to -18 nT) south for over half an hour at the beginning of the storm, which set up Earth’s magnetosphere to be highly activated. This means that any additional strong wind, high density, or prolonged negative Bz can quickly jump the KP back into G1/G2 range.
Here are a couple Tweets share with NLN from tonight’s storming
From the Nidderdale in northern Yorks by @HudsonWeather
It is still possible that there could be additional storming. Keep your eyes on the Solar Wind Data. If there is a prolonged people (more than 45 mins or so) of negative Bz, there could be another round of storming.
Note: The current storm is likely the last for a while. There are now active regions that pose M or X class flare threats on the Sun and the next Coronal hole isn’t expected to reach Earth until late September. Make hay while the Sun shines!