It wasn’t in the forecast but then sometimes the best things aren’t. Let’s just say the aurora is cooking away very nicely across the northern sky with rays to 40 degrees high as of 10 p.m. Some nice curtains near the horizon and even color. I’ve seen obvious pink tops on some of the taller, brighter rays.
Even though the waning gibbous moon is up, if you have a chance, check out the northern sky. Moonlight lowers the contrast of the display some, but once your eyes are dark-adapted, there was lots to see (at least from 8:30-10:30 p.m.). Hopefully the display will continue long into the night.
An unexpected passage of a high-speed solar wind gust that happened to be pointing in the right magnetic direction (south Bz) hooked into Earth’s protective magnetic field and sparked the display. The Kp index, which slumbered all day in the low activity, green zone shot up into the red at Kp=5 during the early evening.
You can stay in touch with what the aurora’s doing overnight by clicking on the Kp link above as well as the Ovation auroral oval site which shows the extent of the aurora.
Good luck in your viewing!
UPDATE 11:45 p.m. CST: Lots of rays and rayed arcs appearing across the north-northeast up to 45 degrees high. The moon is up higher now reducing contrast but still a fine show.
UPDATE 12:10 a.m. Feb. 19 – Intense, thick green arc slung across the bottom half of the northern sky. Pulses of fainter “flaming” aurora rising to the zenith. Sense that a bright eruption might happen soon.
UPDATE Feb. 9 a.m. : The aurora lasted the entire night and peaked around 2-3 a.m. It was still rolling in morning twilight.