Kp Index went to Red

The K Index went to Strormy Red late last night, confirming the magnetometer readings.

The Kp-index
The planetary Kp-index is a globally averaged indicator of the worldwide level of geomagnetic activity. The official Kp index is derived by calculating a weighted average of K-indices from a predetermined network of geomagnetic observatories, the official Kp network. Since some of these observatories are not currently available to SWPC in real-time, it is necessary for an operations center such as ourselves to make the best estimate we can of this index from a subset of the official network. The Space Weather Prediction Center calculates near real-time estimates of the Kp index using eight of the thirteen official Kp network stations. The network of contributing stations is provided through cooperative efforts between SWPC and data provider partners which currently include the U.S. Geological Survey, Natural Resources Canada, the British Geological Survey, German Research Centre for Geosciences (GFZ), Geoscience Australia, with important supplemental contributions from the Institut de Physique du Globe de Paris, and the Korean Space Weather Center.
The K-index
The K-index is a code that is related to the maximum fluctuations of horizontal components observed on a magnetometer relative to a quiet day, during a three-hour interval. The conversion table from maximum fluctuation (nT) to K-index, varies from observatory to observatory in such a way that the historical rate of occurrence of certain levels of K are about the same at all observatories. In practice this means that observatories at higher geomagnetic latitude require higher levels of fluctuation for a given K-index. At SWPC, we monitor the preliminary values of the K-index, minute by minute, from a network of observatories that relay data in near-real time. The final K-indices are determined after the end of prescribed three hourly intervals (0000-0300, 0300-0600, ..., 2100-2400). The maximum positive and negative deviations during the 3-hour period are added together to determine the total maximum fluctuation. These maximum deviations may occur anytime during the 3-hour period.