Will there be Northern Lights July 21?

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Northern Lights Now – On July 16 NLN noted that there was a delta spot on active region 2567. The delta spot didn’t last long, but the active region interacted with AR 2565 to produce several C-class flares over the next 24-36 hours. Early on the 17th, between 5:39 and 9:27 UTC, there was a long duration C1 flare between the two with a period of coronal dimming. Coronal dimming is often a sign that a CME was launched – sure enough a large, but slow CME was launched AND the region was in the Earth strike zone. It get’s better, there is coronal hole pointed towards Earth that could enhance the incoming solar storm. Social media is abuzz with the prospect we might get a solar storm and an aurora show.

Coronal dimming near center disk is a good indicator of a Earth-directed CME
Coronal dimming near center disk is a good indicator of a Earth-directed CME

Not so fast! While the CME had an asymmetric halo signature, it was quite faint. It’s likely there was not a lot of material ejected. Subsequent WSA-Enlil model runs show a small impact from a slow moving CME early on July 21. The model indicate such a diffuse impact that SWPC has chosen not to post a storm watch. The max predicted KP is 4. In addition to that, the moon will be nearly full as a waning gibbous, so at best there will be an hour two of true dark just after sunset.

Bottom line – There is definitely a higher chance for aurora late on the 20th and early on the 21st than at other times. If the orientation of the CME is favorable, or if it is pushed faster than the models suggest by the high speed wind, we could easily see a period of G1 storming. This is a wait-and-see type event, have your cameras charged and ready just in case.

Happy Hunting