From: Space Weather Prediction Center (NOAA)
Posted: Wednesday, May 12, 2021
Space Weather Message Code: ALTK07
Serial Number: 115
Issue Time: 2021 May 12 1259 UTC
ALERT: Geomagnetic K-index of 7
Threshold Reached: 2021 May 12 1258 UTC
Synoptic Period: 1200-1500 UTC
Active Warning: Yes
NOAA Scale: G3 - Strong
NOAA Space Weather Scale descriptions can be found at
Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
Induced Currents - Power system voltage irregularities 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.
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