WARNING: Geomagnetic K-index of 7 or greater expected
Valid From: 2021 May 12 1250 UTC
Valid To: 2021 May 12 1800 UTC
Warning Condition: Onset
NOAA Scale: G3 or greater – Strong to Extreme
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.