Earth is under a severe (G4) geomagnetic storm watch for the first time in nearly 20 years.
The NOAA Space Weather Prediction Center issued a severe (G4) geomagnetic storm watch on Thursday, May 9, for the first time since January 2005.
According to the SWPC, at least five coronal mass ejections (CMEs) were headed toward Earth and expected to arrive midday Friday, May 10, and continue through Sunday, May 12.
Several strong flares were spotted over the last few days and were linked to a large and magnetically complex sunspot cluster. More solar activity is expected from that area. At least five flares associated with CMEs appear to be headed toward Earth.
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What are CMEs? 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 have been known to impact infrastructure in near-Earth orbit and on Earth’s surface. This could potentially disrupt communications, the electric power grid, navigation, radio and satellite operations.
According to SWPC, only three severe geomagnetic storms have been observed during this solar cycle, which began in December 2019. The last G4 (severe) was spotted on March 23, 2024, this triggered a geomagnetic storm alert.
The last G5 (extreme) caused the Halloween storms in October 2003. That G5 caused power outages in Sweden and damaged power transformers in South Africa.
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Difference between a space weather watch, warning, and alert
Here are the definitions of a space weather watch, warning, and alert according to the National Weather Service:
- Watch: A Watch is issued when the risk of a potentially hazardous space weather event has increased significantly, but its occurrence or timing is still uncertain. It is intended to provide enough advanced notice so those who need to set their plans in motion can do so. The purpose of a Watch is to give preliminary notification of possible space weather activity with a lead-time of hours to days. A Watch can be upgraded to a higher-level Watch.
- Warning: A Warning is issued when a significant space weather event is occurring, imminent or likely. A Warning is a short-term, high confidence prediction of imminent activity. The purpose of a Warning is notification of impending space weather activity with a lead-time of minutes to a few hours. A Warning can be upgraded to a higher Warning if space weather conditions are expected to change sufficiently enough to warrant the upgrade.
- Alert: Alerts indicate that the observed conditions, highlighted by the warnings, have crossed a preset threshold or that a space weather event has already started.
What could a G4 geomagnetic storm do?
Severe (G4) geomagnetic storms have the potential to affect power systems, spacecraft operations, and other systems.
Here are the potential effects of a severe (G4) geomagnetic storm:
- Power systems: Possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid.
- Spacecraft operations: May experience surface charging and tracking problems, corrections may be needed for orientation problems.
- Other systems: Induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora has been seen as low as Alabama and northern California (typically 45° geomagnetic lat.).
An extreme (G5) geomagnetic storm is even more rare, only occurring an average of 4 days every 11 years.
Here are the potential effects of an extreme (G5) geomagnetic storm:
- Power systems: Widespread voltage control problems and protective system problems can occur, some grid systems may experience complete collapse or blackouts. Transformers may experience damage.
- Spacecraft operations: May experience extensive surface charging, problems with orientation, uplink/downlink and tracking satellites.
- Other systems: Pipeline currents can reach hundreds of amps, HF (high frequency) radio propagation may be impossible in many areas for one to two days, satellite navigation may be degraded for days, low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40° geomagnetic lat.).
Below is a PDF of a chart from the NOAA that covers the effects of geomagnetic storms, solar radiation storms, and radio blackouts.