The Space Weather Prediction Center (SWPC) said today that G4 (Severe) geomagnetic storm levels were observed at 2350 UTC on September 7 and again at 0151 UTC and 1304 UTC on September 8, due to the effects of a coronal mass ejection (CME). A G3 (Strong) or greater warning was in effect until 1500 UTC today.

Solar flares have adversely affected HF nets attempting to gather information on the three current active hurricanes.

A G4 storm can cause widespread voltage-control problems, and some protective systems may mistakenly trip out key assets from the power grid. HF radio propagation will be sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora may be seen at lower-than-typical latitudes.

A S1-S2 (Minor-Moderate) solar radiation storm warning for 10 MeV protons was extended and is now in effect until September 8 at 2359 UTC. An S1 or S2 solar radiation storm can have minor effects on HF propagation over polar paths.

An X-class flare (R3-strong radio blackout) occurred on September 7 at 1436 UTC. The source region for this flare was Region 2673. A narrow, slow-moving CME was observed with this event, but was determined not to have an Earth-directed component. “This region continues to produce significant flare activity,” the SWPC said.