With many Chicago-area residents getting a fascinating display of the Northern Lights, NBC 5 Storm Team meteorologist Kevin Jeanes explains what a geomagnetic storm is and how it causes the phenomenon.
A geomagnetic storm could potentially make the Northern Lights visible over parts of the Great Lakes this week, according to the National Weather Service’s Space Weather Prediction Center (SWPC).
According to the latest updates from the SWPC, a G2 geomagnetic storm watch has been issued for the early parts of this week after a coronal mass ejection (CME) occurred on Sunday morning.
The solar materials from that CME are expected to arrive to Earth late Tuesday morning, with impacts continuing into Wednesday according to SWPC forecasts.
As a result, the Northern Lights may be visible Tuesday night and into Wednesday morning over several northern and upper Midwest states, including Wisconsin and Michigan. It isn’t expected at this time that enough solar material will arrive at Earth to make the Northern Lights visible in the Chicago area, according to forecast models.
Typically, a G3 or greater geomagnetic storm is required to push the incredible spectacle far enough south for area residents to observe it.
Earlier this year, a G4 geomagnetic storm prompted the SWPC to issue a very rare “geomagnetic storm warning,” its first in nearly 20 years. That storm created an incredible display of the Northern Lights that was visible into the deep south, with Chicago-area residents capturing incredible images of the show for several nights.
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According to the SWPC, CME’s are “large explosions of plasma and magnetized particles from the Sun’s corona.” Those ejections expand in size as they approach Earth’s atmosphere, and can cause geomagnetic storms when the arrive.
The Northern Lights occur when those charged particles hit Earth’s magnetic field, interacting with atoms and molecules in the upper atmosphere and producing brilliant and wavy colors in the sky.
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The Northern Lights are generally visible only at high altitudes, but instances like this week’s geomagnetic storm can cause those particles to be visible across greater distances.