Potential for Mid-May Aurora prompts G1 and G2 storm watch

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Northern Lights Now – The large coronal hole that was pointed directly towards Earth on May 12th and 13th combined with recent solar disturbances prompted space weather forecasters to predict there will be an extended period of aurora activity the third week of May. The Space Weather Prediction Center (SWPC) issued storm watches for three consecutive days with a G1 watch posted for May 16, and G2 watches posted for both May 17 and 18. A G1 storm watch means KP values will likely exceed 4.67 during the 24 hour period, a G2 storm watch means the KP will likely exceed 5.67.

SWPC Notifications timeline shows a G1 watch issued for 5/16 and G2 watches on 5/17 and 5/18
SWPC Notifications timeline shows a G1 watch issued for 5/16 and G2 watches on 5/17 and 5/18

The coronal hole responsible for the expected activity stretched from North to South on the solar disk on May 13. In the image below, the coronal hole is the outlined darker area at the time it was directed towards Earth. High speed solar wind exiting from that region should arrive at Earth around May 16. As it arrives, expect solar wind speed readings from DSCOVR to increase, possibly to as high as 600 km/s. As the higher wind pushes on Earth’s magnetosphere, KP will read higher and any aurora will be stronger during periods of negative Bz.

Coronal Hole Faces Earth on May 13, 2017
Coronal Hole Faces Earth on May 13, 2017

After the initial coronal hole impact, there are two additional features that should impact Earth this week. Part two of this storm will be the arrival of a slow moving CME that launched from the southern hemisphere of the Sun on May 13. This CME is visible on LASCO C2 and C3 imagery, but it is faint. There is a decent chance it will miss Earth entirely to the south and we may see nothing from it. But it may also arrive at Earth as a glancing blow. This is a low confidence forecast, but if it does hit there could be G2 storming due the the magnetosphere already being activated by the initial coronal hole. Here’s an animatedGIF of the CME lauching as seen by LASCO C3:

AnimatedGIF of LASCO C3 shows a faint cloud of Plasma lifting off the Sun, mostly to the South
AnimatedGIF of LASCO C3 shows a faint cloud of Plasma lifting off the Sun, mostly to the South

Finally the third portion of this storm is most promising and is expected to impact Earth on 5/19 and 5/20. This second coronal hole produced great activity on the previous rotation in April. NLN will keep you updated with more information about this CH as it’s structure becomes evident.

Please monitor the Northern Lights Now Twitter feed and the live KP charts for updates on when it may be a good time to go out and watch the northern or southern lights dance.

Happy Hunting

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