Surprise geomagnetic storm arrives early as NOAA warns more solar impacts are on their way today

A geomagnetic storm surprised forecasters overnight as material from recent solar eruptions arrived earlier than expected, briefly reaching strong (G3) levels. Now, NOAA has a G3 geomagnetic storm watch in effect as Earth braces for further impacts from multiple coronal mass ejections (CMEs) launched in quick succession from sunspot region AR4274.

The overnight storm was likely triggered by a glancing CME arrival that combined with lingering effects from a high-speed solar wind stream, according to NOAA's Space Weather Prediction Center (SWPC). The result was a strong burst of auroral activity, with sightings reported across Europe, Canada and the northern U.S.

But more solar storms are still on the way, saving the biggest until last. The M7.4 solar flare that erupted on Nov. 5 also released a CME traveling between 1,100 and 1,400 km/s (around 2.5–3.1 million mph) and is expected to reach Earth later on Nov. 6 or early Nov. 7 (UTC), according to NOAA's SWPC. This incoming CME, combined with a fast solar wind stream from a nearby coronal hole, could trigger another round of strong geomagnetic storming over the next 24 to 48 hours.

What does this mean?

A strong (G3) geomagnetic storm indicates that Earth's magnetic field is heavily disturbed by solar activity. These storms can cause intermittent satellite navigation issues and high-frequency radio disruptions, as well as voltage corrections in power systems, particularly at high latitudes.

Strong geomagnetic storms can also spark bright, dynamic auroras, sometimes much farther into mid-latitudes than normal. If you're located in Canada, northern Europe and the northern U.S., make sure you keep your eyes on the skies tonight, as we could be in for a treat.

Space weather physicist Tamitha Skov described the current forecast as "an aurora photographer's dream starting now and lasting at least through the weekend," adding that G3 to G4 storm levels are possible by Friday as multiple CMEs interact with Earth's magnetic field.

Sunspot region AR4274 remains large and magnetically complex and is continuing to rotate to face Earth, which means more solar fireworks could follow in the coming days.