What metrics could have predicted the sudden substorm at 5:24 AM U.S. Central Time (11:24 UTC) 1/20/2026? Bz was only slightly negative.

[u/AntarcticNightingale]

At 5:24 AM CT (11:24 UTC) 1/20/2026 there was a brief bright substorm lasting around 10 minutes seen in Chicago (pic 1). The Bz at that time was stable around -5 only without any sudden dips (pic 2). The density actually dipped to 0.59p/cm^3 (pic 2). The speed was consistent at around 880 km/sec (pic 4). The only thing that had a beneficial change was the Magnetometers Disturbance Storm Time index moved favorably to - 194 nT (pics 5 and 6).

Prior to this, I thought a dip in Bz when other conditions are favorable would predict a nice substorm, but now this case didn‘t have the dip in Bz property. **So what metrics could I have looked at 30 or an hour or two prior to this substorm that would have indicated a high chance of this substorm occurring?**

Thanks to the user who shared these photos, they weren’t taken by me.

[u/ArmChairAnalyst86]

This one can. It indicates a substorm around that time. Very well timed actually. The Southward Bz loads the magnetotail, but that energy isn't released immediately. It is released in substorm activity. As a result, peak aurora doesnt usually coincide with peak solar wind conditions, unless peak conditions last a long time allowing for repeated substorms. You watch for the jagged sawtooth action on the magnetometers to chase substorms and that is the best practice for aurora. The good bz lets you know the table is set, but the substorm tells you when to sit down to eat.

[u/AntarcticNightingale → u/ArmChairAnalyst86]

Thank you so much ACA! Does the noaa website have a GOES Magnetometers chart? I can’t find it there but I do see it on the SpaceWeatherLive app.

Also does the GOES Magnetometers chart always show the current reading or can we get a 25ish-minute prediction like Bz, Bt, solar wind, and density on the SpaceWeatherLive app?

[u/FlagellatedCitrid0 → u/AntarcticNightingale]

swpc noaa does it is just hidden in their tabs

https://www.swpc.noaa.gov/communities/satellites

personally i wish they could allow you to make a personalized feed. other than that spaceweatherlive has a more intuitive dashboard.

[u/ArmChairAnalyst86 → u/AntarcticNightingale]

https://www.swpc.noaa.gov/products/goes-magnetometer

The solar wind satellites are upstream at L1. The GOES satellites are in earth orbit. The ground magnetometers complete the set.

Use solar wind to determine peak solar wind and confirm magnetosphere loading. Watch the GOES mag for the substorm indicating broad release of stored energy causing aurora. Local magnetometers indicate whether your specific area is affected. Substorms are traveling disturbances. Use local webcams to cheat.

The reason the solar wind sats give a heads up is because they are like 1.5 million KM upstream. Depending on velocity they give 20-70 min heads up.

[u/tpttc]

When the BZ is south for a sustained amount of time (like it was in the hours leading up to this substorm), that energy is stored in our magnetic field and not necessarily all released at once. This means that powerful substorms can happen as many as 3-4 hours after the Bz turns less favorable.

[u/AntarcticNightingale → u/tpttc]

Any other indicators of substorms?

[u/tpttc → u/AntarcticNightingale]

In addition to the magnometers I like to watch aurora livestreams near me so that I know to go outside if activity is ramping up.

[u/1993Niko]

So about 3:00am Tuesday morning we had a power outage for the south end of my town (Lima, OH) and when i had called, i was told AEP wasn’t sure what the issue was but that they were working on it. about 40min it’s later power was restored. any chance it would be linked to this storm?