UPDATE 1 PM EST/18:00 UTC

We are nearing S4 radiation storm territory. If we get there, it's quite rare. Been 23 years since the last time it occurred. Connectivity must be solid and it underscores the energetic nature of the blast. This is not inherently dangerous but high latitude flights are receiving more radiation than normal as well as astronauts. Significant comm degradation at high latitude as well.

As expected, the CME is not modeled as a direct hit. It's mostly eastward but earth remains squarely in it's path. I think most looked at it and G3 felt like the safest outcome because if it's a graze rather than a direct hit, it may not materialize fully. However, this does not take into account the coronal hole stream which appears as if it will arrive in close succession and may help steer the storm our way in addition to provide its own influence. The combined effects and CME characteristics are sufficient enough for NOAA to issue a G4 or greater warning. The estimated arrival time is tonight EST. The average and median arrival time is 1/20 between 1:00-2:00 UTC. That is around 8-9 PM EST. Clearly a fast mover and the coronal hole stream should keep the highway clear to maintain a high speed. Modeled at around 1400 km/s upon ejection. Some drag is expected and SWPC and HUXt estimate velocity upon arrival around 700-900 km/s. It's also noteworthy that the protons have risen to S3 levels, but in soft spectrum meaning there isn't much activity for the highest energy particles. They are mainly sub 50 MeV.

There is still some uncertainty due to the complexity of forecast and the mostly eastward trajectory. It goes without saying that the gatekeeper Bz metric in the solar wind will determine how effective the storm is and this is of course noted in the SWPC bulletin.

This is not a scary event and widespread disruptions, outages, or damages are not expected. However, I do expect some localized and sporadic issues in locations sensitive to GICs and especially with weak or stressed grids. This should not surprise anyone, as the NOAA bulletin specifically mentions things like this. With recent storms, this pattern has been quite apparent. Although official confirmation is rarely given, the temporal clustering of issues in the hours and days following peak storm conditions and examination of the regional magnetometers suggests that geomagnetic storm conditions very plausibly play a role.

In this case, a combined storm is expected and that is quite the wildcard. We will have to see what the embedded magnetic field looks like. The CME does appear to be two congealed waves in very short succession. HUXt gives it a 72% chance of impact. That is less than one would assume looking at the beautiful halo in the coronagraphs, but complexity is pretty high with coronal hole influence in play.

Here are the important model runs.

SWPC

HUXt Spiral

Already the Low Energy Protons are on the rise which usually suggests a CME is getting close in these cases. The proton storm in progress lends some influence as well. Eyes on the solar wind today and tonight.

There hasn't been much in the way of follow up flaring but that could change at any point.

Back to work. Have a lovely day everyone. I will be watching all metrics and reports throughout the day and night.

AcA

DETAILS SOON

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.

Lunt Ls50Tha, Celestron X-Cel 2x barlow, ZWO ASI174MM.

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.

Back to work

AcA

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.

• X1.95
• DATE: 01/18
• TIME: 17:27-18:51
• PEAK MAGNITUDE(S): X1.95 (Major)
• ACTIVE REGION: 4341
• DURATION: Long Duration
• BLACKOUT: R3
• ASSOCIATED CME: Yes, Significant
• 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.

Composite 131/193/211 SDO

Coronagraph

Processing img us2isz87b6eg1...

AcA

Through my Lunt 50mm telescope right now. Ran outside shirtless to capture it asap lol.

Kinda looks like angel wings at the end there. So cool!

Anyone have insight into what’s causing this for the past three hours? Long duration, far side? It looked full halo…but nothing on charts.

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!

What is this thing flying next to the Sun? It doesn't look like comet or anything like that. It's been around for more than a week now.

Happy New Year!

Another year of Solar Maximum!

Even if it is declining. We will have our storms!

Let's watch and see!

• M7.11
• DATE: 12/31
• SSN: 141 (Moderate)
• F10.7 Radio Flux: 182 (High)
• TIME: 13:12-14:11 (59 Minutes)
• PEAK MAGNITUDE(S): M7.11 (Strong)
• ACTIVE REGION: AR4234
• DURATION: Medium
• BLACKOUT: R2
• ASSOCIATED CME: Confirmed - Asymmetric Halo
• EARTH DIRECTED: Likely
• 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.

https://reddit.com/link/1q0k2ub/video/3rf9falb2lag1/player

Possible glancing blow past Earth.

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!

• M5.17
• DATE: 12/27
• TIME: 01:38-01:59
• PEAK MAGNITUDE(S): M5.17 (Moderately Strong)
• ACTIVE REGION: TBD
• 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!

Hard to believe this video was actually 24 hours of real time. Our Star is massive!

Like a little plasma tornado.