Northern Light Now – The long absence of large solar flare activity may come to an end soon as solar cycle 25 active regions start to appear. The last C-class flare occurred on May 15, 2019 from active region 12741. In the 7 months since, there have been only 19 active regions numbered as the Sun has been in the depths of the cyclic solar minimum. For aurora hunters, the only source of activity has been from an occasional filament eruption and High Speed Streams originating at Coronal Holes. However, over the last several months there are indications that the next solar cycle is picking up and activity will return over the next year. Aurora hunters should start looking forward to the next season.
The Solar Cycle lasts about 11 years. During each cycle, activity increases for about five and a half years. The monthly count of active regions and sunspots visible on the Sun increases until Solar maximum. At maximum, the Sun’s polarity flips and activity slowly tapers back into solar minimum over the remaining five and a half years in the cycle. Currently, the Sun is in the least active part of this cycle and as a result there have been fewer and weaker aurora displays over the last year.
Solar Cycle 24 (SC24) started in January of 2008 and peaked in July of 2013 and is ending now. At peak, there were nearly 300 active regions numbered in 2013. There were only 22 new active regions numbered in 2019. There is normally an overlap between the end of one solar cycle and the beginning of the next. Of those 22 active regions numbered in 2019, only 17 actually belong to SC24, the other 5 are part of Solar Cycle 25.
When Will Solar Activity Increase?
By the start of the next northern hemisphere aurora season! Aurora hunters can expect the 6 to 9 months ahead to continue to have very low solar activity. During the minimum between SC23 and SC24 there were about 30 months with fewer than seven active regions numbered. In the current minimum, the last month with more than seven active regions identified was September of 2017 – or 27 months ago. This is an arbitrary threshold, but can prove useful when making an estimate. Projecting out and assuming the same length of solar minimum, May or June should be the first month with 7 newly numbered active regions of Solar Cycle 25.
While there won’t be much activity from CMEs originating at active regions, it will certainly be possible that there will be activity from coronal holes. Attentive space weather fans will have noticed over the last couple years that Coronal Holes are the primary driver behind aurora activity during solar minimum. It is possible there will also be activity from filament eruptions (link to what happened today). Overall, the frequency of storms should be about the same over the last 6 months as it will be over the next 6 months – that is to say, not much.
The frequency and magnetic complexity of SC25 regions will continue to increase. With each new region, the likelihood of the next C-class flare increases. Seasoned aurora hunters know that long duration C, M and X class flares are one of the keys to a good northern lights display. Of course, a more complex AR could develop at any time and produce an strong flare, it is just far less likely during solar minimum. So keep watching the data and keep watching the active regions.
Northern Lights Now – SWPC has posted a G2 storm watch for this weekend. The arrival of a coronal hole high speed wind stream should bring a couple periods of active aurora. Here’s the expected timeline.
Northern Lights Now – Space weather forecasters are predicting a period of G1 and G2 aurora conditions May 15th-17th. NLN is activating the live blog. We’ll aim to update several times a day, or as warranted, so check back often.
NLN Live Blog Update – Saturday, May 18, 04:30 UTC (18:00 EST 5/17)
Live blog time: 52hrs 30min
Calling it. It’s over. This is the last post in this storm’s live blog.
@HaloCME on twitter has offered a compelling explanation as to what happened to this week’s storm. In short, it came early. The G2-G3 storming we saw on Tuesday the 14th was the complex eruption from May 10-11. The follow-on storms arrived on 5/15 as we mentioned in the Thursday, May 16, 05:20 UTC live blog post. Later on the 15th and 16th instability as a result of the pushed the KP as high as KP=3.
The recent G3 storm on May 14 was not just because of CIR followed by HSS, but contributed also by a CME (likely from May 11). Note the periods of depressed proton temperature and smooth field rotation. Looks like another one (from May 13) may be hitting us. pic.twitter.com/c6VGoM4XBT
Thank you as always for following along this storm with NLN. We’ll still be in solar minimum for the next year and a half, but as the G3 storming earlier this week shows, there will still be activity. Please follow NLN on Twitter, Facebook and Instagram.
NLN Live Blog Update – Friday, May 17, 04:30 UTC (00:30 EST 5/17)
Live blog time: 52hrs 30min
Thanks for checking back in. Nothing to report. We are awaiting the third transient. With each hour that passes, it become less likely we will see it.
A quick reminder: take a look at the ways to support NLN. Most don’t cost anything.
NLN Live Blog Update – Friday, May 17, 00:30 UTC (2030 EST 5/16)
Live blog time: 48hrs 30min
Quick update: Nothing to see here.
It’s still been quiet, with a max recorded KP=3. The G2 storm watch is expired, we are now in a G1 storm watch. This is when aurora hunters start guessing the odds that the watch is a dud.
NLN Live Blog Update – Thursday, May 16, 20:30 UTC (16:30 EST 5/16)
Live blog time: 44hrs 30min
Looking at the Bz again there have been two periods of 58 minutes and 60 minutes in the last 6 hours. Individually, these are not enough to produce activity beyond KP=2. They do, however, prime the magnetosphere to react more quickly during the next phase of Bz.
There is no indication yet that the next CME is incoming. Watch and wait.
NLN Live Blog Update – Thursday, May 16, 18:00 UTC (14:00 EST 5/16)
Live blog time: 42hrs 00min
Looks like we had the next CME arrival. Take a look at the 24 and 6 hour solar wind charts. At about 16:40 on the 16th, Bz shifted deeply south, Bt and wind speed showed slight increases. Bz south lasted about an hour, then orientation switched back to the north. Once again, a small impact CME unlikely to cause much aurora.
Some Enlil model runs had the second and third CMEs merging together. While there is a slight chance this aurora event is over, we’ll keep our fingers crossed for the third CME arriving over the next 12 hours.
For hopeful hunters, there is another potential explanation: it’s possible the CME arrival just now was part of the first CME from the complex eruption on May 10 that the Enlil model had merged together. If this is the case, we could see another arrival of the official second CME soon – with the third still waiting for tomorrow.
NLN Live Blog Update – Thursday, May 16, 05:20 UTC (01:30 EST 5/16)
Live blog time: 29hrs 30min
Looking back at the 24 hour solar wind profile (below) it looks like the first CME hit around 18:00 UTC on 5/15. At that time the solar wind speed suddenly becomes more variable, Bt jumps then drops off, and Bz goes from fairly stable to slowly decreasing. This isn’t a classic ICME shock, but it is enough of a change in the background variables that we’ll call it a shift and the indicator of a passing transient.
Bz has been mostly south over the last hour, but it would need to be at -5 for over 45 minutes for there to be much aurora. With the passing of the first CME complete, aurora hunters will need to wait for the next CME expected to arrive later today.
NLN Live Blog Update – Wednesday, May 15, 23:20 UTC (19:20 EST 5/15)
Live blog time: 23hrs 20min
First indication the CME is arriving. Proton density has dropped. We’ll need to wait some more to know the real magnetic structure.
NLN Live Blog Update – Wednesday, May 15, 21:15 UTC (17:15 EST 5/15)
Live blog time: 21hrs 15min
Still waiting for first CME shock.
Let’s talk Moon:
Tonight we have a waxing gbbous Moon. For just about everyone, the Moon will be rising 4:00 and 5:00 in the afternoon and setting between 4am and 5am. It is nearly 80% full and the brightness will work against aurora hunters. There’s not much we can do about this aside from go out between moonset and sunrise or cross our fingers that the aurora is strong enough to see through the moonlight. Drier air will help as it reflects less moonlight.
Over the next three days, Moonset and Moonrise become 45 mins later each night, but the moon continues to get brighter until it is Full on Saturday.
NLN Live Blog Update – Wednesday, May 15, 18:30 UTC (14:30 EST 5/15)
Live blog time: 18 hrs 30min
The expected incoming storm is complex. Many times there is a single flare, or filament eruption that prompts a watch from SWPC. This time there are three separate solar events responsible for the activity. First, A complex combination of a flare and two filament eruptions (7 degrees and 13 degrees) from the interaction between AR2740 and AR 2741 launched CMEs late on May 10 and early on May 11. These CMEs merged and should arrive any moment.
Next Another filament, this time 10 degrees erupted from near center disk around 8pm UTC on 5/12. This CME should arrive in about 24 hours and will likely be the biggest impact we see. Timing is harder to estimate when multiple CMEs are between Earth and Sun so the timing on the second CME has a wider variance than normal (read: don’t worry if it’s late)
Third, another smaller filament happened eruption on May 13. This eruption was slightly more to the west of the second eruption and should give Earth a glancing blow. It is possible that this third CME will merge into the second on and we will only see the second – particularly if the second is slower than forecast and the third is faster.
You can see all of 3 CMEs on the Elil model output below (see: How to Read the Enlil Model ) as curved lenses of activity moving from the Sun towards Earth. The upper plot on the right shows three arrivals as peaks in density.
NLN Live Blog Update – Wednesday, May 15, 16:30 UTC (12:30 EST 5/15)
Live blog time: 16 hrs 30min
Still awaiting the arrival of the first shock. Bt is around 8, Proton density is between 13 and 15 parts per cubic centimeter, and wind speed is steady around 470km/s. Those are all slightly elevated levels. We’ll know the first shock arrives when those each make a sudden shift. For now: Watch and wait.
NLN Live Blog Update – Wednesday, May 15, 04:30 UTC (00:30 EST 5/15)
Live blog time: 4 hrs 30min
If you are wondering whether you are going to be able to see aurora where you live, here’s a handy map. G2 is KP=6. (click to enlarge)
When G2 storming is going on Aurora may be visible across Canada, Central and northern New England, the Great Lakes Region, the Upper Midwest, Alaska, Northern Russia, the Scandinavian Countries, Scotland, and Very Northern Ireland. In the Southern Hemisphere, KP=6 is enough to give the entire South Island of New Zealand a show as well as Tasmania and the South Pole. Of course, you can’t see aurora if the sky is bright, so most of the northernmost spots won’t have a chance due to the midnight sun.
NLN Live Blog Update – Wednesday, May 15, 04:15 UTC (00:15 EST 5/15)
Live blog time: 4 hrs 15min
NLN is expecting at least three separate storm arrivals over the next three days with a chance for a forth. Here are some more details on the expected timings of when there may be G1 and G2 storming. Please note: because this is a complicated forecast, this graphic should be taken with a grain of salt. We could easily see a prolonged period of G2 and some G3, or no G2 at all. We also expect storming to go beyond the end of the three day forecast window.
NLN Live Blog Update – Wednesday, May 15, 04:00 UTC (00:00 EST 5/15)
Live blog time: 4 hrs 0min
SWPC has updated the watches for the anticipated set of storms. There are now G1 watches posted on both 5/15 and 5/17 and a G2 storm watch posted for 5/16.
NLN Live Blog Update – Wednesday, May 15, 00:00 UTC (20:00 EST 5/14)
Live blog time: 0min
Live blog activated. We are expecting this to be a multi-storm several day complex event. Thanks for live blogging with NLN.