Strong G3 geomagnetic storm watch for 23 March

Saturday, 22 March 2025 17:58 UTC

Interesting stuff indeed. When we look at SOHO/LASCO coronagraph imagery we see that the eruption launched a faint but rather fast coronal mass ejection with the bulk of the ejecta heading to the south-east. The NOAA SWPC issued a strong G3 geomagnetic storm watch as it anticipates an arrival early tomorrow, 23 of March.

But why the strong G3 geomagnetic storm watch? It does sound a bit over the top to issue a strong G3 geomagnetic storm watch (Kp7) for what seems like an underwhelming coronal mass ejection but the solar wind environment around Earth is already disturbed and along with the high solar wind speeds expected from this coronal mass ejection of around 800km/s it could cause quite a significant geomagnetic response with the right interplanetary magnetic field parameters. Also we should not forget that the equinox effect also might play a part in NOAA's decision to issue a G3 watch as aurora activity is slightly more common and elevated around the equinoxes.

All in all... like always.. no guarentees... the coronal mass ejection is a bit faint on the coronagraph imagery as you can see for yourself which could result in a lackluster impact but it does seem likely to us that this plasma cloud is indeed going to arrive at our planet. Will it be around 6 UTC tomorrow (23 March) as NOAA predicts? That might be on the fast end of the prediction scale but for sure an impact tomorrow is likely. Be sure to keep an eye on the data to see how this story developes when the CME arrives!