Space Weather Message Code: WARK04Serial Number: 3987Issue Time: 2021 Dec 21 0437 UTCEXTENDED WARNING: Geomagnetic K-index of 4 expectedExtension to Serial Number: 3986Valid From: 2021 Dec 21 0206 UTCNow Valid Until: 2021 Dec 21 0900 UTCWarning Condition: OnsetNOAA Space Weather Scale descriptions can be found atwww.swpc.noaa.gov/noaa-scales-explanationPotential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude.Induced Currents – Weak power grid fluctuations can occur.Aurora – Aurora may be visible at high latitudes such as Canada and Alaska.