The National Oceanic and Atmospheric (NOAA) Space Weather Prediction Center (SWPC) has issued a geomagnetic storm warning for July 30 through August 1 due to intense solar activity. If the forecasted G3 conditions materialise, auroras may be visible across mid-latitudes around 50°. NOAA SPWC reports that previous geomagnetic storms of this intensity have triggered auroras as far south as Illinois and Oregon.
On July 29 at 8.27 pm EDT (0027 on July 30), the first of several incoming coronal mass ejections (CMEs) impacted Earth’s magnetic field, triggering a minor geomagnetic storm.
Space weather physicist Tamitha Skov commented on X, “This is an auspicious start to the multiple storm train we are expecting over the next few days,” in response to a post from NWS Riverton about auroras observed as far south as Wyoming, US during the solar storm.
The cause of the geomagnetic storm warning is a series of powerful M-class solar flares that erupted from the sun over the weekend, accompanied by several coronal mass ejections (CMEs). The first two CMEs merged, forming a “cannibal CME” that is clearing a path for at least two additional CMEs following behind it, according to Spaceweather.com. The CMEs are expected to arrive between July 30 and early August 1, although the exact timing is uncertain.
Coronal Mass Ejections (CMEs) carry electrically charged particles known as ions through space. As CMEs collide with Earth’s magnetic field, they have the potential to initiate geomagnetic storms. Throughout these events, the ions interact with atmospheric gases, emitting energy in the form of light. This phenomenon manifests as the aurora borealis in the Northern Hemisphere and the aurora australis in the Southern Hemisphere.
NOAA uses a G-scale to classify the intensity of geomagnetic storms, ranging from G1 (minor) to G5 (most extreme). Based on the current geomagnetic storm watch issued by NOAA, a G3-class storm is expected for July 30, with G2 periods predicted for July 31. The G-scale serves as a tool for categorizing the strength and potential impact of these geomagnetic events.