NOAA’s Space Weather Prediction Center (SWPC) has issued a G2 (moderate) geomagnetic storm watch for August 4, and a G1 (minor) watch for August 5.

“A coronal hole high-speed stream, originating from a recurrent, positive polarity coronal hole…is likely to cause geomagnetic storming at the G2 level on 4 August 2017, and at the G1 level on 5 August,” the SWPC said.

“During storms, the currents in the ionosphere, as well as the energetic particles that precipitate into the ionosphere, add energy in the form of heat that can increase the density and distribution of density in the upper atmosphere, causing extra drag on satellites in low-Earth orbit,” the SWPC explains on its website. “The local heating also creates strong horizontal variations in the in the ionospheric density that can modify the path of radio signals and create errors in the positioning information provided by GPS. While the storms create beautiful aurora, they also can disrupt navigation systems such as the Global Navigation Satellite System (GNSS) and create harmful geomagnetic induced currents (GICs) in the power grid and pipelines.”

There have been anecdotal reports of auroral-mode propagation on 2 meters in Norway and Finland.