A G2 geomagnetic storm developed on October 31 as fast solar wind reached Earth. The planetary disturbance index reached six, while an observer photographed auroras in Anchorage. Visibility farther into the North American evening remained conditional on the disturbance continuing, with different prospects for high and middle latitudes.
A G2 geomagnetic storm developed on October 31, with the planetary Kp disturbance index reaching six. A fast solar-wind stream was expected to arrive over October 31 and November 1. The disturbance brought an evening aurora outlook for high North American latitudes, provided conditions continued for several more hours.[1], [2]
On October 31, solar-wind speed measured 579.6 kilometres per second and density stood at four protons per cubic centimetre. The interplanetary magnetic field measured 7.8 nanotesla, including a southward component of 5.9 nanotesla. These measurements accompanied the disturbance around Earth; the strongest solar flare in the preceding 24 hours was separately listed as a B6 event.[1]
Todd Salat photographed auroras from his back deck in Anchorage, Alaska, at 01.00 local time on October 31. The image supplied a specific observation alongside the broader outlook. Forecast probabilities varied with latitude: the high-latitude table gave a 60 percent chance of severe storm conditions over the next 24 hours, compared with ten percent at middle latitudes. The minor-storm probabilities were 25 percent at high latitudes and 30 percent at middle latitudes.[1]
