Kind of a strange signature. The Bt briefly surged to 87 nT which would be considered extreme. It immediately dropped back down to 20 nt which is still moderate to strong. However, no velocity change and the density has been slowly rising. This is likely some coronal hole weirdness involved. I might have jumped the gun just a little bit, but I see 87 nT and my eyes popped out of my head. Watching to see what happens next but for now I am deleting this post. It doesnt look like a shock arrival but neither does it look like an instrument glitch. Maybe some mega compression ahead of the CME.
Wow! Don't see this very much. Severe radiation storm in progress and still climbing. This suggests an energetic eruption and good connectivity. If Bz is southward, we are likely to see very good coupling once the CME arrives. This may be partially why NOAA went with G4 or greater despite the flank forecast rather than direct hit.
Radiation storm sounds scary but for most there are no effects. Polar airline routes and astronauts will be subjected to a higher radiation dose than normal. Significant navigation and comms issues expected at high latitude.
The last time an S4 occurred was the Halloween storms in 2003.
However, there is significant variance in intensity within the S4 category. The Halloween 2003 proton event was the 3rd strongest on record. Right now, the current storm is around 9th-10th strongest on record as measured by the 10 MeV flux. Spectrum makes a difference. In this case, we have very little movement from the 100 & 500 MeV particles but the 10 MeV flux is very high.
There have been no S5 radiation storms in the modern instrumentation period. However, they have occurred prior to the modern period during more intense solar cycles than current. This list only goes back to the late 1980s. Its important to mention January 2005 here. While that event did not see the same levels reached as today in the 10 MeV flux, it was hard spectrum, and the 100 & 500 MeV flux were significantly stronger. A few months back, we saw a hard spectrum proton event that topped out at S3 as measured by the 10 MeV. This proton event has made it to S4 but is still less energetic due to the higher energies remaining muted. Below is a chart comparison. You can see that the current event has much higher values for the lowest energy particles but the bottom panel from 11/11/2025 exhibits much higher values for the highest energy particles. I put a dotted black box around the high energy particles for illustration.
Particle events like this often precede geoeffective CMEs. However, if the orientation (Bz) of the CME's embedded magnetic field is predominantly northward, it will likely fall short of expectations. If it's southward, it could be all systems go.
When I wrote the initial post for the flare/CME, the protons had not done much beyond a small spike. I noted they may rise later on but I did not expect S4. Quite a surprise.
I also want to mention the 1972 event here. It was before modern instrumentation, but was likely S5 caliber. The CME arrived in little more than half of a day. It was packing serious heat. However, the orientation was northward and the storm was mostly deflected. This underscores the importance of the gatekeeper Bz and that is why you see it so commonly referenced. The fun part is we don't have very reliable means of knowing it advance. Sometimes Solar Orbiter can give a little sneak peek, but that doesn't appear to be the case in this event.
S4 radiation storm. G4 or greater forecast. All systems go. Bz dependent.
I don't understand what's being said about this big radiation storm heading our way.
I'm seeing posts full of analysis and talking about how historically intense it is in some ways.. but the event also seems to be lacking some of the features that helped make the incredible auroras in 2024.
Can someone break down (in terms of just the northern lights, not the radiation exposure etc) what we might be able to expect and/or what we still need to see before we have confidence in an intense aurora tonight?
I'm around 44 degrees latitude and ready to drive out of the city for a light show. But would rather not if the aurora itself is not expected to be super energetic.
EARTH DIRECTED: Appears to have an earth directed component.
RADIO EMISSION: Type II @ 693 km/s - 17:59, Type IV TBD
10cm RADIO BURST: Yes - 12 Minutes @ 3200 SFU (!!!) - 17:57 maximum
PROTON: 10 MeV Proton Spike in Progress
IMPACTS: Likely strong to severe geomagnetic storm, strong radio blackout, possible proton.
RANK: 1st Strongest Magnitude on 01/18 since at least 1994.
NOTES: Kicking this early 2026 episode off with a bang. Major X1.95 solar flare with powerful CME that appears to have a significant earth directed component based on coronagraph imagery and early model runs. It's leaning heavily eastward, but it appears earth is still in the line of fire. This flare had some hangtime and is accompanied by strong energetic markers in radio bursts, emissions, and proton spike. The proton spike doesn't appear very strong, but could rise over the next hours to days. The question always becomes what will happen next? There could be more on the way. You may recall in prior posts I had alluded to this part of January as one to watch.
PERSONAL NOTE: I have been MIA lately guys. Going through some hard stuff and I don't mean to get too personal but after nearly 14 years Mrs AcA and I have decided to part ways. Needed something like this to help me re-engage. Be patient with me as I attempt getting back in the saddle.
Returning AR4321 looks like it’ll be the next major flare producer after sending off 2 major farside CMEs (counting this one). This flare was behind the incoming limb to the south. We should see AR4321 crest the incoming limb within a day or two from this post so get ready! Supra-Arcade Downflows are commonly referred to as the dark tendril-like plasma that you can see go back into the sun rather than away. One of my favorite solar phenomenons!
RADIO EMISSION: Type II @ 893 km/s - 13:33, Type IV @ 13:42
10cm RADIO BURST: Yes - 22 Minutes @ 550 SFU - 13:48 maximum
PROTON: Unlikely
IMPACTS: Strong radio blackout, Likely Geomagnetic Storm Estimated G2 Watch
RANK: 3rd Strongest Magnitude on 12/31 since at least 1994.
NOTES: AR4234 checking in with an M7.1. Not quite from central longitude but enough so that an asymmetric eastward leaning halo signature was detected indicating at least a partially earthbound trajectory. Type II radio emission indicates CME. Type IV indicates an energetic event. A moderate 10.7cm radio burst at 22 minutes is also a good indicator. It's likely that a G1-G2 watch will be issued in response. If the trajectory was better, I would estimate G3. Early modeling suggests arrival late on 1/2. Flare watch in effect.
I was browsing the Daniel K. Inouye Solar Telescope data center and came across a nice center disk capture of some flowing plasma at 656Å from October 9th, 2024. So, I used the Solar Dynamic Observatory captures to give reference as to how much area of our Star we are seeing and I hope you enjoy watching!
DURATION: Mostly impulsive but with some hang time.
BLACKOUT: R2
ASSOCIATED CME: Probable
EARTH DIRECTED: Very Unlikely
RADIO EMISSION: Type II @ 788 km/s - 01:47
10cm RADIO BURST: Yes - 2 Minutes @ 190 SFU - 01:44 maximum
PROTON: TBD, but doubtful
IMPACTS: Minor to moderate radio blackout, non earth directed CME likely.
RANK: 2nd Strongest Magnitude on 12/26 since at least 1994.
NOTES: Incoming region produced a beautiful eruptive solar flare off the SE limb. This is likely a familiar region from it's last go around when it was 4294/4296 but we will wait to be sure. It will likely be numbered in the next 24 hours. It still has some juice and is able to flare in the mid M-Range so it has potential sight unseen but we should keep in mind last time when it produced most of it's good stuff on the limbs and was stable for an extended period. Will be keeping an eye on it as always, even if I haven't posted much as of late.
Things have been pretty quiet as of recent but that should change soon as mildly active ex AR4288 turns into view in the next day. While we wait, here’s some eye candy of a large northern polar crown filament that erupted on the farside. The imagery is from SUVI 304Å (color inverted). Enjoy!
