As part of the Space Weather Prediction Center's rollout of our improved website, the content from the Geomagnetic Indices Lists and Plots page is being provided in a new way.
Try the following page:
R1 (Minor) Radio Blackout Impacts
HF Radio: Weak or minor degradation of HF radio communication on sunlit side, occasional loss of radio contact.
Navigation: Low-frequency navigation signals degraded for brief intervals.
More about the NOAA Space Weather Scales
Navigation: Low-frequency navigation signals degraded for brief intervals.