Negative polarity CH HSS sparks G2 – Moderate geomagnetic storm
Image credit: NASA/SDO AIA, LMSAL
Earth is under the influence of negative polarity coronal hole high speed stream (CH HSS) over the past 24 hours, sparking G2 geomagnetic storming. The source is a polar connected coronal hole located in the Sun's southern hemisphere.
Geomagnetic K-index of 5 (G1 – Minor geomagnetic storm) threshold was reached at 07:10 UTC, followed by K-index of 6 (G2 – Moderate) at 08:00 UTC.
Under G2 conditions, the area of impact is primarily poleward of 55 degrees Geomagnetic Latitude.
Power grid fluctuations can occur, high-latitude power systems may experience voltage alarms, satellite orientation irregularities may occur, increased drag on low Earth-orbit satellites is possible, HF (high frequency) radio propagation can fade at higher latitudes and aurora may be seen as low as New York to Wisconsin to Washington state.
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Space Weather Message Code: ALTK05
Serial Number: 1316
Issue Time: 2021 Mar 20 0712 UTC
ALERT: Geomagnetic K-index of 5
Threshold Reached: 2021 Mar 20 0710 UTC
Synoptic Period: 0600-0900 UTC
Active Warning: Yes
NOAA Scale: G1 – Minor
Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents – Weak power grid fluctuations can occur.
Spacecraft – Minor impact on satellite operations possible.
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Space Weather Message Code: ALTK06
Serial Number: 478
Issue Time: 2021 Mar 20 0803 UTC
ALERT: Geomagnetic K-index of 6
Threshold Reached: 2021 Mar 20 0800 UTC
Synoptic Period: 0600-0900 UTC
Active Warning: Yes
NOAA Scale: G2 – Moderate
Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents – Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft – Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio – HF (high frequency) radio propagation can fade at higher latitudes.
Aurora – Aurora may be seen as low as New York to Wisconsin to Washington state.
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Teo Blašković founded The Watchers in 2011 and edited it until 2026, covering seismic and volcanic activity, extreme weather, space weather and near-Earth objects. Articles on this page are his archive.
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