On Thursday, the National Weather Service’s Space Weather Prediction Center Issued a Severe (G4) Geomagnetic Storm Watch.

UPDATE #3: At approximately 22:54 UTC (6:54 PM EST) the Geomagnetic Storm reached the level G5, becoming the first G5-rated Solar Storm since the 2005 Halloween Storms, which caused an hour-long power outage in Sweden. In addition to causing a power outage, those Solar Storms caused Aurora Borealis sightings as far south as Texas and Florida.

UPDATE #2: At 18:00 UTC (2:00 PM EST) the Space Weather Prediction Service posted a SEVERE (G4) Geomagnetic Storm ALERT, after the K-index, the measurement of magnitude for geomagnetic storms, reached 7.67.

UPDATE: At approximately 16:00 UTC (12:00 PM EST) on Friday, May 10, the Space Weather Prediction Center increased the number of observed Coronal Mass Ejections to 7, with an expectation of the storms persisting from midday Friday through Sunday. In addition, a minor solar storm (S1) was announced. We will continue monitoring the situation as it occurs.

May 10, 2024
By Heath Scofield

At 23:02 UTC (7:02 PM EST) on Thursday, May 9, the National Oceanic and Atmospheric Administration released the following Media Advisory.

“NOAA’s Space Weather Prediction Center (SWPC) — a division of the National Weather Service — is monitoring the sun following a series of solar flares and coronal mass ejections (CMEs) that began on May 8. Space weather forecasters have issued a Severe (G4) Geomagnetic Storm Watch for the evening of Friday, May 10. Additional solar eruptions could cause geomagnetic storm conditions to persist through the weekend.

A large sunspot cluster (UPDATE:17 times the diameter of Earth) has produced several moderate to strong solar flares since Wednesday at 5:00 am ET. At least five flares were associated with CMEs that appear to be Earth-directed. SWPC forecasters will monitor NOAA and NASA’s space assets for the onset of a geomagnetic storm.

CMEs are explosions of plasma and magnetic fields from the sun’s corona. They cause geomagnetic storms when they are directed at Earth. Geomagnetic storms can impact infrastructure in near-Earth orbit and on Earth’s surface, potentially disrupting communications, the electric power grid, navigation, radio and satellite operations. SWPC has notified the operators of these systems so they can take protective action. Geomagnetic storms can also trigger spectacular displays of aurora on Earth. A severe geomagnetic storm includes the potential for aurora to be seen as far south as Alabama and Northern California.”

In addition to the above message, the SWPC held a conference this morning where additional information was provided for the press and other concerned individuals from across the country.

During the conference, SWPC Service Coordinator Shawn Dahl described how this is the first G4 watch issued since the Solar Filament Impact on January 21, 2005. That solar storm did end up as a G4, however it did not have major impacts. There have been other G4-rated solar storms since then, including three since December 2019, when Solar Cycle 25 began.

Additionally, Dahl explained how a solar storm watch, much like a tornado watch, only suggests there is potential for an event, and that it will not be known until the CMEs reach satellites in a position called Lagrange-1, which is 1.5 million km (~930,000 miles) from Earth in the direction of the sun.

At that point, the size and orientation of the CMEs will be measured, and solar storm warnings may be issued. The size of a CME is important for determining the strength, while the magnetic orientation determines how effectively the Earth’s Magnetosphere (Magnetic Field) will be able to repel the storm.

This storm may cause issues with communication, navigation, and infrastructure, however organizations and companies who may be affected have been warned already by the SWPC, including power companies and FEMA.

For most individuals, the only major impact would be finding cloud-free skies away from light pollution such as in cities, as it is highly likely that this storm will allow ground observers to see Aurora Borealis here in Central Ohio, either with the naked eye or through a mobile phone. The best visibility will be after sunset tonight until a little after midnight, at which point clouds may make visibility more difficult.