Having just photographed a G3 strong geomagnetic storm on the night of 7-8 Oct, imagine my surprise when a long lasting X1.8 solar flare on the sun launched another coronal mass ejection (CME) of plasma directly toward the earth on the next night. This CME was expected to arrive during the middle of the day on Thursday, Oct 10. The NOAA Space Weather Prediction Center issued a G4 severe geomagnetic storm watch for 10-11 Oct. In a G4 or G5 storm in Virginia, it is possible to have the aurora directly overhead, with much of the aurora visible to the naked eye.
For those of us in Northern Virginia who missed the G5 extreme storm on May 10th (due to rain and cloudy skies), this was a very exciting development. The May 10th storm was the strongest display of aurora since 2003! As predicted, the effects of the CME began to arrive around noon on 10 Oct.
We departed for Shenandoah National Park around 4:30 pm with high hopes that the CME-driven storm would continue late into the night. We arrived at Hogback Mountain overlook around 6 pm and set up our cameras. As the sun began to dip below the horizon at 7:30 pm, we could already see red aurora to the north reaching high into the sky.
As the skies grew dark, the aurora conditions were approaching G5 extreme storm levels:
The aurora faded after twilight, partially washed out by the moon. However, at 10:20 pm, a severe-strength substorm once again put on an impressive aurora display:
Around 1 am on 11 Oct, another substorm lit up the sky.
The NOAA Space Weather Prediction Center recorded the peak of the G4 storm from 1100 am 10 Oct – 0200 am 11 Oct Eastern Standard Time (1500 10 Oct – 0600 11 Oct UTC). KP values during substorms clocked in at 7+ to 8+. It was a wild ride!