JACKSON, Wyo. — A second appearance of the aurora borealis over Jackson in the same week? It’s looking likely!
A severe geomagnetic storm watch has been issued by the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC) following the eruption of a coronal mass ejection from the sun on Oct. 8. The G4 storm is predicted to reach a Kp index of 8.33 overnight on Thursday, Oct. 10, likely making the Northern Lights visible over northern states including Wyoming. SWPC noted that reaching G5 (extreme) storm levels remains possible.
Derived from the German “Planetarische Kennziffer,” or planetary index, the Kp scale runs from zero to nine. As explained by Wyoming Stargazing, the Kp index “measures the disruption of the horizontal distribution of the geomagnetic activity…A value of zero means that even Fairbanks, Alaska, would have difficulty in seeing the northern lights. One to three is most common, and that’s what is frequently seen in those northern latitudes of northern Canada and Alaska. A four would push them down into southern Canada, while a five, in the right conditions, might just barely be visible on the northern horizon here in Jackson Hole. To see them well, we typically need at least a six.”
Monday night’s display was the result of a Kp index peaking at 7.33. In May, the Kp index reached 9.
The National Weather Service’s Riverton Office forecasts patchy fog in northwestern Wyoming on Thursday night, however, and wildfire smoke could affect visibility. The waxing quarter moon might also be a factor. Even if viewing conditions are perfect, it’s difficult to predict the aurora with much certainty.
“Space weather is very fickle,” National Weather Service Riverton Meteorologist Chris Hattings has said about the aurora in past forecasts.
To try to view the aurora, head to a very dark place away from light pollution and allow the eyes to adjust, which could take 15 to 30 minutes. Turn to the north-northeast and look at the horizon.
Keep an eye on the Space Weather Prediction Center to see how the forecast evolves.
