Space Weather Message Code: ALTK04 Serial Number: 2212 Issue Time: 2021 Apr 17 2344 UTC ALERT: Geomagnetic K-index of 4 Threshold Reached: 2021 Apr 17 2344 UTC Synoptic Period: 2100-2400 UTC Active Warning: Yes NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents – Weak power grid fluctuations can occur. Aurora – Aurora may be

Space Weather Message Code: WARK04 Serial Number: 3882 Issue Time: 2021 Apr 17 2333 UTC WARNING: Geomagnetic K-index of 4 expected Valid From: 2021 Apr 17 2330 UTC Valid To: 2021 Apr 18 0900 UTC Warning Condition: Onset NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents – Weak power grid fluctuations can occur. Aurora

Space Weather Message Code: WARK06 Serial Number: 441 Issue Time: 2021 Apr 17 0813 UTC WARNING: Geomagnetic K-Index of 6 expected Valid From: 2021 Apr 17 0812 UTC Valid To: 2021 Apr 17 1200 UTC Warning Condition: Onset NOAA Scale: G2 – Moderate NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude. Induced Currents – Power grid

Space Weather Message Code: ALTK05 Serial Number: 1326 Issue Time: 2021 Apr 17 0753 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2021 Apr 17 0746 UTC Synoptic Period: 0600-0900 UTC Active Warning: Yes NOAA Scale: G1 – Minor NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents – Weak power grid fluctuations can occur.

Space Weather Message Code: ALTK05 Serial Number: 1325 Issue Time: 2021 Apr 17 0601 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2021 Apr 17 0559 UTC Synoptic Period: 0300-0600 UTC Active Warning: Yes NOAA Scale: G1 – Minor NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents – Weak power grid fluctuations can occur.

Space Weather Message Code: WARK05 Serial Number: 1594 Issue Time: 2021 Apr 17 0533 UTC EXTENDED WARNING: Geomagnetic K-index of 5 expected Extension to Serial Number: 1593 Valid From: 2021 Apr 16 1925 UTC Now Valid Until: 2021 Apr 17 1200 UTC Warning Condition: Persistence NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents –

Space Weather Message Code: ALTK05 Serial Number: 1324 Issue Time: 2021 Apr 17 0202 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2021 Apr 17 0200 UTC Synoptic Period: 0000-0300 UTC Active Warning: Yes NOAA Scale: G1 – Minor NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents – Weak power grid fluctuations can occur.

Space Weather Message Code: ALTK05 Serial Number: 1323 Issue Time: 2021 Apr 16 2027 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2021 Apr 16 2025 UTC Synoptic Period: 1800-2100 UTC Active Warning: Yes NOAA Scale: G1 – Minor NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents – Weak power grid fluctuations can occur.

Space Weather Message Code: WARK05 Serial Number: 1593 Issue Time: 2021 Apr 16 1923 UTC WARNING: Geomagnetic K-index of 5 expected Valid From: 2021 Apr 16 1925 UTC Valid To: 2021 Apr 17 0600 UTC Warning Condition: Onset NOAA Scale: G1 – Minor NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents – Weak power

Space Weather Message Code: ALTK04 Serial Number: 2211 Issue Time: 2021 Apr 16 1840 UTC ALERT: Geomagnetic K-index of 4 Threshold Reached: 2021 Apr 16 1838 UTC Synoptic Period: 1800-2100 UTC Active Warning: Yes NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents – Weak power grid fluctuations can occur. Aurora – Aurora may be