G3 – Strong geomagnetic storm in progress, G3 or greater – Strong to Extreme warning in effect

SDO AIA 211, 193 and 171 - April 7, 2022

An equatorial, negative polarity coronal hole high speed stream (CH HSS) coupled with waning coronal mass ejection (CME) influence produced a G3 – Strong geomagnetic storm conditions early April 10, 2022. Conditions could further escalate and even reach G4 – Strong or G5 – Extreme conditions.

Geomagnetic K-index of 5 (G1 – Minor geomagnetic storm) threshold was reached at 04:27 UTC, followed by K-index of 6 (G2 – Moderate) at 04:46 UTC and K-index of 7 (G3 – Strong) at 05:10 UTC.

G3 – Strong geomagnetic storm potential impacts:

  • Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
  • Induced Currents – Power system voltage irregularities are possible, false alarms may be triggered on some protection devices.
  • Spacecraft – Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur.
  • Navigation – Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur.
  • Radio – HF (high frequency) radio may be intermittent.
  • Aurora – Aurora may be seen as low as Pennsylvania to Iowa to Oregon.

At 05:12 UTC, SWPC issued a Geomagnetic K-index of 7 or greater warning, suggesting G4 -Severe or even G5 – Extreme geomagnetic storm conditions are possible. The warning is valid through 09:00 UTC.

According to the SWPC forecasters, the conditions are caused by a negative-polarity coronal hole high speed stream.

3-hour K-indices for 7 days to April 10, 2022
Coronal Holes and Active Region map - April 8, 2022
RTSW 3 days ending April 10, 2022
RTSW 1 day - April 10, 2022
SDO AIA 211, 193 and 171 - April 10, 2022
SDO AIA 211, 193 and 171 - April 7, 2022

Featured image credit: NASA SDO/AIA, TW


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  1. Not only the strength of Earth’s magnetic has declined but also, the space environment surrounding Earth has become more conductive and as a result the high energy particles of the solar wind and cosmic rays are now traveling faster. These are the reasons why even minor solar storm can produce major changes in Earth’s magnetosphere and generate strong geomagnetic storms.

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