Earth faces back-to-back geomagnetic storms on August 27 and 28, as a fast solar wind stream from a coronal hole and incoming coronal mass ejections from an M6.9 solar flare combine to trigger G1 minor and G2 moderate storm watches and potential northern lights sightings at lower latitudes.
Skywatchers and aurora chasers are on alert after NOAA’s Space Weather Prediction Center (SWPC) issued a moderate (G2) geomagnetic storm watch for Friday (Aug. 28), as coronal mass ejections (CMEs) launched from the sun yesterday (Aug. 25) head toward Earth. NOAA’s SWPC has also issued a minor (G1) geomagnetic storm watch for Thursday (Aug. 27), as a stream of fast solar wind from a coronal hole is expected to buffet Earth ahead of the incoming CMEs.
The M6.98 solar flare erupted from the active sunspot region 4513 and peaked at 6 a.m. EDT (1000 GMT), according to SpaceWeatherLive. 4513 has been particularly active over the previous 24 hours, firing off a barrage of solar flares including five powerful M-class eruptions. Solar flares are ranked by strength into five classes — A, B, C, M and X — with each class 10 times more powerful than the one before it. M-class flares are the second-strongest category, sitting just below the most powerful X-class eruptions.
The eruption also triggered a moderate (R2) radio blackout across the sunlit side of Earth, affecting high-frequency radio communications over parts of Africa, Europe and the Arctic. Several CMEs left the sun that day and NOAA’s SWPC now anticipates their arrival at Earth.
Back-to-Back Geomagnetic Storm Watches for August 27 and 28
Earth could face back-to-back geomagnetic storms on August 27 and 28. A G1 storm may arrive from a coronal hole, while CMEs launched on August 25 could trigger a stronger G2 storm. Two geomagnetic storm watches have been issued for Aug 27-28, featuring a G1 storm on Aug 27 and a G2 storm on Aug 28.
On August 27, Earth could encounter a stream of fast solar wind. It is expected to come from a coronal hole on the Sun, which are regions where the Sun’s magnetic field opens into space. Solar particles can escape through them at unusually high speeds. When this high-speed stream reaches Earth, it can disturb our planet’s magnetic field, prompting the G1 geomagnetic storm watch.
The bigger event could follow a day later. A G2 moderate geomagnetic storm watch has been issued for August 28, triggered by a series of coronal mass ejections (CMEs) that erupted from the Sun on August 25. If they arrive as expected, they could produce stronger disturbances than the preceding solar-wind stream. NOAA forecasts isolated G1 to G2 conditions across Aug. 27-28 due to the combined influence of the high-speed solar wind stream and the incoming CME activity.
What Lower-Latitude Skywatchers Can Expect
During G2 geomagnetic storm conditions, the northern lights can push farther south than usual, potentially becoming visible across parts of the northern U.S. and northern Europe. A G2 storm could create opportunities for aurora sightings at unusually low latitudes.
If the glancing CME arrival coincides with antennas and the high-speed solar wind stream, the two influences could work together to ramp up geomagnetic activity and potentially enhance aurora activity. How much of an impact the CME ultimately has will depend on its exact arrival time and, crucially, the orientation of its magnetic field when it reaches Earth. A strong southward magnetic field would interact more effectively with Earth’s magnetic field, increasing the chances of stronger geomagnetic activity. However, visibility depends on the storm’s actual strength and local conditions, and a storm watch is not a guarantee that the predicted storm will occur at its expected intensity.
Solar Activity Trends and What Comes Next
While Earth remains safe from the solar eruptions themselves, our planet’s magnetic shield could soon be in for a turbulent ride. Forecasters will keep a close eye on the latest models and space weather forecasts as Friday approaches.
