JACKSON, Wyo. — Geomagnetic activity is expected to put on a light show in the sky over the next few nights, and the action might be visible as far south as Wyoming.
The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center issued a strong geomagnetic storm watch for Oct. 4 through Oct. 6 following the observation of coronal mass ejections associated with a major solar flare on Wednesday, Oct. 2. Plasma from the ejections will interact with upper levels of the Earth’s atmosphere, generating the famous colors. Geomagnetic activity could be visible in the sky through Saturday night.
The Kp index is expected to reach level 7 on Saturday night. Some activity might be detectable beginning as early as 9 p.m. on Friday night, when the Kp index is expected to hit 6.67. 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.”
The National Weather Service’s Riverton Office forecasts partly cloudy skies in northwestern Wyoming on Friday night, but clear skies on Saturday night. Following the new moon on Wednesday, there should be little interference from the waxing crescent moon. Even if viewing conditions are perfect, though, 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 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.
Jackson was treated to a stunning Northern Lights display in May, when a severe geomagnetic storm lit up the skies.
Keep an eye on the Space Weather Prediction Center to see how the forecast evolves.
