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!
Northern Lights Now – The fall aurora season kicks off around the end of August when the nights in the Nordic countries (Sweden, Finland, Norway, Iceland and Denmark) start to get long enough and dark enough to see the northern lights. This year, the season should start off with a bang as a G1 storm is predicted that should bring a nice show.
Northern Lights Now Twitter follower Mia Stålnacke captured these pictures in Sweden earlier this week as aurora season gets under way.
Earth will come under the influence of a coronal hole, a corotating interaction region (CIR) and a solar storm over the next several days. There is a chance conditions may reach G2 on September 1st as the edge of a solar storm delivers a glancing blow.
On August 31st the high speed winds generated by the coronal hole shown below will start to push on Earth’s magnetosphere. The CH, which is the dark area on the image below, covers much of the northern hemisphere and crosses into the southern hemisphere. That means it is highly likely the winds will pick up at Earth about 3 days after the region was pointed towards Earth on the center of the disk. At about the same time, the CIR will also arrive. Current models indicate the solar wind speeds could reach between 550 and 600 km/s.
Later, on Sept 1 a small solar storm that was released during an eruption near active region 2672. Watch that eruption in this video. The eruption happened on the very western edge of the Earth stike zone and is not large. Most of the plasma emitted will miss earth to the west, but in the WSA-Enlil model below, see that the flank of the cloud may brush by Earth. Earth’s magnetosphere is likely to be activated as a result of 36 hours of high speed wind. That activation should accentuate any impact from the solar storm.
With this space weather setup, there is a good chance that at least one of the features will produce G1 storming (KP=5 or higher) in the next three days. If the solar storm is oriented just right, and is moving slightly faster than modeled and arrives in closer proximity to the high speed solar wind, KP values may reach G2 storm levels. Below is the official forecast from SWPC as displayed by the NLN auroraCast clock. Orange shows periods when G1 storming is expected:
Aurora hunters should be watching the data over the next three days and have their cameras ready.
Northern Lights Now – A large coronal hole pointed towards earth means there may be many as 72 hours of G2 storming between September 28 and September 30. It is likely that during that time KP values will occasionally be above 5.67 and the aurora borealis will treat Aurora hunters to a show. Refresh this page often as we’ll be posting live updates as this storm impacts Earth.
Update #11: 72:00 hours in, 0000 UTC 9/31/2016 (8:00pm EST 9/30/2016)
The interplanetary shock from the previous update did not usher in a significantly different solar wind environment. This storm has been exhausting and frustrating for Aurora hunters around the world. It’s tempting to call the storm over – the G2 watch is now expired – however, a quick peak at the SDO AIA 211 image of the Sun from yesterday indicates there may be one more round of enhanced solar wind on it’s way. Notice that there is a final “leg” of the coronal hole pointed towards Earth in the 9:00am UTC image form 9/29 in the Earth strike zone. It’s possible this will bring enhanced solar wind speeds in the second half of today. Starting in about 12 hours and lasting for between 12 and 24 additional hours will be the final chances for this storm to put on a real show. It’s frustrating, but it’s storms like this that make the storms where there is a good show that much more awesome!
The storm hasn’t been a total bust. Check out this Timelapse from Adam Hill Studios in the North West Territory:
Update #10: 69:15 hours in, 2115 UTC 9/30/2016 (5:15pm EST 9/30/2016)
It’s been quiet. The solar wind has been blowing past Earth consistently and in a non-aurora producing orientation. Until about 20 minutes ago. DSCOVR data reflected an interplanetary shock arriving, it can be seen as a sudden shift in solar wind parameters. Bz shifted quickly north, wind speed decreased and proton density dropped. Sometime this indicates a shift in the space weather environment. In this case, after a period of about 10 minutes, the Bz shifted back to the south. If it stays this way, G1 storming could pick back up. In fact, wingKP models are responding to this change and predicting a return to G1 conditions in the next 45 minutes. Here’s a snapshot of the data during the shock arrival:
Update #9: 52:30 hours in, 0430 UTC 9/30/2016 (12:30am EST 9/30/2016)
There has now been 24 hours of continuous solar wind stronger than 650 km/s. Solar wind hit a peak earlier today of over 800 km/s, which is solidly in the “very strong” range. The charged particles that are carried in the solar wind exert a force on the Earth’s magnetosphere. The force is cumulative and it acts like slowly continuing to push harder on a spring. The more “compressed” the magnetosphere is, the more likely it is to react to any periods of high proton density, strong Bt, or negative Bz. This is why magnetometers are measuring KP values in the G1 range despite only brief periods of south oriented Bz that have been occurring today.
The short story is that Earth is primed to put on an amazing aurora display if the solar wind becomes even slightly favorable for aurora. When/if it happens, there will be between 30-60 minutes of warning.
Update #8: 47:00 hours in, 2300 UTC 9/29/2016 (07:00pm EST 9/29/2016)
Wrapping up the second full day of G2 storm watch, and the third day of active storming. Today there have been 4 periods of G1 storming recorded. There should be more G1-G2 storming over the next 24 hours with the possibility for some G3 if the Bz cooperates (which it hasn’t been doing much of so far this storm.
Update #7: 36:30 hours in, 1230 UTC 9/29/2016 (08:30am EST 9/29/2016)
Since the last update, there has been nearly consistent G1 storming. Pictures of aurora and proton acrs started rolling in on Twitter. Take a look at the 6 hours chart from NLN’s current KP page showing consistently KP5+
These two twitter post show proton arcs that happened overnight for this storm, one in Montana, the other was visible in the North Caithness coast
Update #6: 29:00 hours in, 0500 UTC 9/29/2016 (01:00am EST 9/29/2016)
Just a quick update. The negative Bz did infact lead to a small substorm. KP is back to G1 levels. Check out that same webcam now, it is showing much more green:
Update #6: 28:15 hours in, 0415 UTC 9/29/2016 (12:15am EST 9/29/2016)
On of the great things about the internet is that people hook up webcams and share them with the world. Check out www.sebeclake.net where you can watch aurora live when it’s cloudy where you are. Right now, it’s clear in Eastern Main and the webcam is showing some faint green on the horizon:
On that note, after it has been quiet for the last 3-4 hours, the Bz has been oriented negative for over 15 minutes now at a strength of more than -5Bz. This means there could be a small substorm coming in the next 30-60 minutes. Watch that KP!
Update #5: 26:00 hours in, 0200 UTC 9/29/2016 (10:00pm EST 9/28/2016)
About one third of the way through the predicted duration of the late September active period and so far the storm is mostly as expected. There have been 2 periods of G2 storming recorded so far and 7 periods of G1. Solar wind has continued to stay in the range of 600-725km/s.
Those strong KP readings are all the more impressive because Bz has been variable, rarely staying negative for more than about an hour. That indicates the long duration of strong solare wind as primed the magnetosphere for a big show if there is a period of negative Bz that lasts a couple hours. Here is the 24 hour view of solar wind data, note that Bz is continuously shifting between negative (south) and positive (south) orientation (click to see full size image):
We have not seen a lot of great pictures from this storm so far. Lots of the traditional Aurora hot spots are clouded in. Hopefully it clears out for some of you over the next 48 hours. Please share your pictures with as at @northLightAlert on Twitter!
Update #4: 20:45 hours in, 2045 UTC 9/28/2016 (5:45pm EST 9/28/2016)
G2 storming is ongoing now!
Update #3: 11:00 hours in, 1100 UTC 9/28/2016 (7:00am EST 9/28/2016)
Activity has decreased a bit over the last 9 hours. One additional period of G1 storming was recorded since the last update, current KP estimates are between 3 and 4 which is not enough for most of our readers to have a chance of seeing a show.
In the lull, let’s take a quick look at NLN’s dynamic inforgraphic of DSCOVR solar wind data. The chart below shows the strength and duration of the wind. Generally, more taller bars mean a better chance of a higher KP. The height of bars indicate how long the solar wind has been favorably exceeded the threshold along the bottom. For example, below: wind speed has been above 400km/s for over 48 hours, above 500km/s for over 18 hours, and above 600 km/s for an hour. One of the most important factors for aurora is Bz, the value on the right of the chart, when it is negative and has been for more than an hour or two, that is some of the best time to go out on the hunt. The chart updates automatically – no need to refresh that page!
Update #2: 3.5 hours in, 0330 UTC 9/28/2016 (11:30pm EST 9/27/2016)
The official G2 watch period has started. There has been G1 and G2 activity consistently over the previous 24 hours, even before the offical watch period begins. This has happened without Bz making a sustained southward shift. Solar wind exceeded 700km/s for about an hour just after midnight GMT. Any sustained period of south oriented Bz could make for a very strong aurora display.
In the 0030 SWPC aurora forecast discussion, there are a pair of notes that it is possible that storming could reach G3 levels over the next three days. This would mean KP values of 6.67 and above!
Update #2: t-2 hours, 2200 UTC (6:00pm EST) 9/27/2016
The storm is rolling! G2 storming levels we reached in the 6:00pm UTC hour. Solar wind speeds are now over 650km/s and there have been periods of south oriented Bz. Here’s the reported 3-hour KP values from SWPC:
Aurora reports are already streaming in! Check out these northern lights that happened just after sunset in Iceland:
Update #1: t-20 hours, 0400 UTC (midnight EST) 9/27/2016
SWPC increases duration of storm watch to 72 hours. Here are the updated timings of this G2 storming. It is important to note that these specific timings are less meaningful in a long duration event like this as it’s likely that the exact timing of KP spikes will depend on when substorms carried by the solar wind arrive at Earth.