Supplemental Info:
The current list of Watches include: 11 Nov G2 (Moderate); 12 Nov G4 (Severe); and 13 Nov G3 (Strong). These Watches are in response to potential geomagnetic storm effects related to coronal mass ejections (CME) that have erupted from the Sun over the past several days.
G4 (Severe) Geomagnetic Effects Include:
Power systems: Possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid (e.g., transformers or substations in high-latitude regions like the northern U.S., Canada, and Europe).
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.).
Potential for higher intensity depending on coronal mass ejection (CME) arrival and magnetic field orientation. Earlier CMEs over the past two days may merge ("cannibal CME" effect) to amplify the storm. No widespread blackouts are forecasted—disruptions would likely be localized and brief, with utilities prepared to mitigate.
View NOAA Space Weather Scales https://www.swpc.noaa.gov/noaa-scales-explanation
Read the Full Advisory: https://www.swpc.noaa.gov/news/g4-severe-watch-effect-12-november
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