|The Estimated 3-hour Planetary Kp-index is derived at the NOAA Space Weather Prediction Center using data from the following ground-based magnetometers: Sitka, Alaska; Meanook, Canada; Ottawa, Canada; Fredericksburg, Virginia; Hartland, UK; Wingst, Germany; Niemegk, Germany; and Canberra, Australia. These data are made available thanks to the cooperative efforts between SWPC and data providers around the world, which currently includes the U.S. Geological Survey, Natural Resources Canada (NRCAN), the British Geological Survey, the German Research Centre for Geosciences (GFZ), and Geoscience Australia. Important magnetometer observations are also contributed by the Institut de Physique du Globe de Paris and the Korean Space Weather Center
K-index Watches are issued when the highest predicted K-index for a day is K = 5, 6, 7, or >= 8 and is reported in terms of the NOAA G scale.
K-index Warnings are issued when NOAA K-indices of 4, 5, 6, and 7 or greater is expected.
K-index Alerts are issued when the NOAA K-index reaches 4, 5, 6, 7, 8, or 9 in a 3-hour period.