Space Weather Message Code: WATA20 Serial Number: 825 Issue Time: 2018 Apr 20 1536 UTC WATCH: Geomagnetic Storm Category G1 Predicted Highest Storm Level Predicted by Day: Apr 21: G1 (Minor) Apr 22: None (Below G1) Apr 23: None (Below G1) THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT 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.

Space Weather Message Code: WARK04 Serial Number: 3464 Issue Time: 2018 Apr 20 1045 UTC EXTENDED WARNING: Geomagnetic K-index of 4 expected Extension to Serial Number: 3463 Valid From: 2018 Apr 20 0032 UTC Now Valid Until: 2018 Apr 20 2359 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 65 degrees Geomagnetic Latitude. Induced Currents –

Space Weather Message Code: ALTK05 Serial Number: 1215 Issue Time: 2018 Apr 20 0953 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2018 Apr 20 0953 UTC Synoptic Period: 0900-1200 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: ALTK06 Serial Number: 460 Issue Time: 2018 Apr 20 0825 UTC ALERT: Geomagnetic K-index of 6 Threshold Reached: 2018 Apr 20 0825 UTC Synoptic Period: 0600-0900 UTC Active Warning: Yes 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 fluctuations can occur. High-latitude

Space Weather Message Code: WARK06 Serial Number: 416 Issue Time: 2018 Apr 20 0714 UTC WARNING: Geomagnetic K-Index of 6 expected Valid From: 2018 Apr 20 0714 UTC Valid To: 2018 Apr 20 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: 1214 Issue Time: 2018 Apr 20 0651 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2018 Apr 20 0650 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: 1213 Issue Time: 2018 Apr 20 0558 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2018 Apr 20 0558 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: WARK04 Serial Number: 3463 Issue Time: 2018 Apr 20 0512 UTC EXTENDED WARNING: Geomagnetic K-index of 4 expected Extension to Serial Number: 3462 Valid From: 2018 Apr 20 0032 UTC Now Valid Until: 2018 Apr 20 1500 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 –

Space Weather Message Code: WARK05 Serial Number: 1468 Issue Time: 2018 Apr 20 0511 UTC WARNING: Geomagnetic K-index of 5 expected Valid From: 2018 Apr 20 0510 UTC Valid To: 2018 Apr 20 1200 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: 2050 Issue Time: 2018 Apr 20 0300 UTC ALERT: Geomagnetic K-index of 4 Threshold Reached: 2018 Apr 20 0259 UTC Synoptic Period: 0000-0300 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