Space Weather Message Code: WATA30 Serial Number: 187 Issue Time: 2021 May 23 2010 UTC WATCH: Geomagnetic Storm Category G2 Predicted Highest Storm Level Predicted by Day: May 24: None (Below G1) May 25: G1 (Minor) May 26: G2 (Moderate) THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT Comment: Minor to moderate geomagnetic storm levels are expected on 25-26 May due to CME effects. NOAA Space Weather Scale descriptions can be

Space Weather Message Code: WARK04 Serial Number: 3903 Issue Time: 2021 May 20 1757 UTC EXTENDED WARNING: Geomagnetic K-index of 4 expected Extension to Serial Number: 3902 Valid From: 2021 May 20 0900 UTC Now Valid Until: 2021 May 21 0300 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: 1332 Issue Time: 2021 May 20 1348 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2021 May 20 1336 UTC Synoptic Period: 1200-1500 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: 1602 Issue Time: 2021 May 20 1212 UTC WARNING: Geomagnetic K-index of 5 expected Valid From: 2021 May 20 1213 UTC Valid To: 2021 May 20 1800 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: 2220 Issue Time: 2021 May 20 1124 UTC ALERT: Geomagnetic K-index of 4 Threshold Reached: 2021 May 20 1124 UTC Synoptic Period: 0900-1200 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: 3902 Issue Time: 2021 May 20 0857 UTC WARNING: Geomagnetic K-index of 4 expected Valid From: 2021 May 20 0900 UTC Valid To: 2021 May 20 1800 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: WARK04 Serial Number: 3901 Issue Time: 2021 May 18 0855 UTC EXTENDED WARNING: Geomagnetic K-index of 4 expected Extension to Serial Number: 3900 Valid From: 2021 May 18 0025 UTC Now Valid Until: 2021 May 18 1500 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: ALTK04 Serial Number: 2219 Issue Time: 2021 May 18 0601 UTC ALERT: Geomagnetic K-index of 4 Threshold Reached: 2021 May 18 0559 UTC Synoptic Period: 0300-0600 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: 3900 Issue Time: 2021 May 18 0023 UTC WARNING: Geomagnetic K-index of 4 expected Valid From: 2021 May 18 0025 UTC Valid To: 2021 May 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: WATA20 Serial Number: 895 Issue Time: 2021 May 16 0037 UTC WATCH: Geomagnetic Storm Category G1 Predicted Highest Storm Level Predicted by Day: May 17: None (Below G1) May 18: G1 (Minor) May 19: 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.