Clear skies over Metro Vancouver this weekend make for ideal star-gazing conditions. And amateur astronomers and photographers could be in for a spectacular show.

That's because the northern lights might reappear over North America as a result of a geomagnetic storm.

The U.S. Space Weather Prediction Center issued a "G3 (strong) Geomagnetic Storm Watch" for Saturday (October 30) and Sunday (October 31) after NASA's Solar Dynamics Observatory spotted a "coronal mass ejection"—i.e. a solar flare.

"Impacts to our technology from a G3 storm are generally nominal," the agency states on its website. "However, a G3 storm has the potential to drive the aurora further away from its normal polar residence and if other factors come together, the aurora might be seen over the far Northeast, to the upper Midwest, and over the state of Washington."

According to the U.S. Space Weather Prediction Center, geomagnetic storms result from variations in solar winds, which affect currents, plasmas, and fields in the magnetosphere of the Earth.

"The largest storms that result from these conditions are associated with solar coronal mass ejections (CMEs) where a billion tons or so of plasma from the sun, with its embedded magnetic field, arrives at Earth. CMEs typically take several days to arrive at Earth, but have been observed, for some of the most intense storms, to arrive in as short as 18 hours."